Hybrid Batteries

Frequently Asked Questions

You likely have questions about our hybrid battery conditioning and maintenance services. Below, are the ones we hear most often. See more on our educational blog. Feel free to contact us if you don't find what you want to know.

What is the difference between a hybrid vehicle battery and an electric vehicle battery?

What is the difference between a hybrid vehicle battery and an electric vehicle battery?

Hybrid vehicles and battery electric vehicles (BEV or EV) have two main things in common, electric motor-generators (MG) and a battery pack. The battery pack, in both cases, is like the fuel tank in a conventional vehicle, storing energy to power the MG and vehicle electrical systems. Unlike the fuel tank in a conventional or hybrid vehicle, however, the battery pack can also be recharged by the car itself, via the MGs.

At their most basic level, electric vehicle and hybrid vehicle battery packs are a collection of rechargeable cells arranged to hold a specified amount of energy. In this way, they are identical. On the other hand, there are a couple of key differences in chemistry, charging capabilities, and maintenance.

Chemistry and Capacity

The main difference between hybrid vehicle and electric vehicle battery packs is their chemistry. For example, the 2010 Toyota Prius NiMH (nickel-metal hydride) hybrid battery pack holds just 1.3 kWh (kilowatt-hours). This is enough to power the MGs for a maximum of a couple of miles stop-and-go traffic in EV-Mode. The 2012 Toyota Prius Plug-In, on the other hand, features a Lithium-ion (Li-ion) hybrid battery, which is about twice as energy-dense as NiMH. Thus, the Prius Plug-In’s 4.4 kWh Li-ion battery pack, at 330 lbs, weighs three times more than the 1.3 kWh NiMH pack in the Prius, yet offers fifteen times more EV-Mode range, up to 15 miles in certain circumstances.

Finally, in electric vehicles whose sole energy source is the battery pack, we see a significant jump in battery capacity. The 2015 Nissan Leaf, for example, is equipped with a 24 kWh Li-ion battery pack, featuring an average range of 84 miles. The Tesla Model S 85 kWh, on the other hand, has a range of about 300 miles. Making the switch to Lithium-ion rechargeable battery chemistry makes this possible, because NiMH or SLA (sealed lead acid) batteries would be too heavy.

Charging Capabilities

The other main difference between hybrid vehicle and electric vehicle battery packs is how they are charged. Hybrid vehicles, such as the Toyota Prius and Ford Fusion Hybrid, do not feature a charge port for the hybrid battery. Instead, they are charged by the MGs, driven by the ICE or during regenerative braking. Plug-in hybrid vehicles, on the other hand, feature a charge port for their small hybrid battery packs. The Prius Plug-In, for example, takes about 90 minutes to charge on an LII (Level 2, 240 V, 30 A) charging station. Once the 15 miles of EV-Mode capacity is used up, the car reverts to regular hybrid vehicle operation, using a small part of the hybrid battery capacity for improved fuel economy and stop-and-go traffic performance.

Electric vehicle battery packs, which have the largest battery capacity, can only be charged by electric vehicle charging stations and, to a lesser degree, regenerative braking. The Nissan Leaf’s 24 kWh battery pack, for example, takes about four hours on an LII charging station, or as little as thirty minutes on an LIII (Level 3, 480 V, 3 Φ, 125 A) charging station. On an LIII charging station, Tesla Model S 85 kWh can fully charge in about an hour.

The Hybrid Shop

The Hybrid Shop has proven scientifically that hybrid battery conditioning is a cost-effective solution to restore hybrid vehicle performance and fuel economy. Battery conditioning, however, only applies to NiMH battery chemistry.

Some plug-in hybrid vehicles, and most battery electric vehicles, are powered by Li-ion battery packs, which cannot be conditioned. When Li-ion battery capacity and power performance wane, new or rebuilt battery packs are the only viable options. The Hybrid Shop can determine which modules require replacement, rebuilding an electric vehicle battery pack being typically less-expensive than buying a new battery pack.


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Will a Hybrid Battery Last as Long as a Standard Battery?

Hybrids Usually Use Two Types of Batteries

Hybrid electric vehicles (HEVs) have two batteries. Like a normal car, they have a low-voltage battery that powers systems such as the stereo, computers, and navigation system. They also have a high-voltage battery, called the traction battery, that powers systems like the vehicle’s electric motor-generator unit and air conditioning compressor.  The traction battery is the expensive one because of its complexity and the exotic materials required to construct it. Most people know how long to expect their car battery to last, so a common question is whether or not their hybrid battery will last as long as their standard battery.

So… What’s the Difference? Why do Car Batteries Fail?

The low-voltage battery in a hybrid vehicle is a sealed lead-acid (SLA) battery. These are heavy but relatively simple. Without going into too much detail about their construction or electrochemistry, they’re constructed of a series of lead plates separated by an electrolyte, in this case a solution of sulfuric acid and water. When the battery is discharged, lead sulfate forms on the surface of the plates, releasing stored energy and gradually reducing the surface area of the plates and the battery’s power. During charging, this substance is dissolved, and the battery’s sulfuric acid level rises back to normal. Over time the sulfate crystallizes and can no longer be dissolved during charging, degrading the battery’s overall capacity permanently. For a typical driver, under optimal conditions an SLA can be expected to last about 3-6 years, though even a single deep discharge can ruin it, no matter its age.

The traction battery in most hybrids is a Nickel-Metal Hydride (NiMH) battery. These are constructed of cells composed of nickel and metal hydride plates, separated by a potassium hydroxide electrolyte. Over time, barring the battery being overheated or physically damaged, NiMH batteries “go bad” because a resistive layer of crystals forms on the surface of the nickel. As with SLA batteries, time is more important than mileage to this process, and driving conditions and habits are more important than either. Under typical conditions, NiMH batteries are expected to last about 5-10 years, though prolonged rest periods or getting overheated by strenuous charging and discharging cycles (such as when driving in mountainous terrain on a regular basis) can shorten that life expectancy.

Can Anything Be Done To Extend the Life of a Hybrid’s Batteries?

In the case of the vehicle’s low-voltage SLA battery, unfortunately the answer is a conditional “no.” Proper maintenance, driving the vehicle daily, or putting the battery on a trickle charger during long storage periods can maximize the battery’s life expectancy, but once the sulfate is crystallized over most of the surface of the lead plates, the battery can’t be revived as a whole unit and must be replaced. Fortunately, SLA batteries are made of fairly common materials and are thus reasonably affordable.

Traction batteries on the other hand are more advanced and made of rarer materials.  This makes them anything but affordable, with the cost of replacement ranging from $2,500 to $8,000 or even more! Fortunately in the case of NiMH batteries in particular, in most cases, the battery can be revived as a whole unit without needing to be discarded or remanufactured. For about a third-to-half the cost of a new battery, The Hybrid Shop can restore up to 95% of a NiMH battery’s initial power, energy, and life expectancy through a proprietary, scientifically-developed process called conditioning.

By cycling the battery between 0% and 100% states-of-charge (the vehicle’s computer keeps it between 38% and 82% for various reasons beyond the scope of this article), the resistive layer of crystals can be broken up and the battery’s performance restored.  In laboratory settings, NiMH batteries have been shown to be able to be conditioned many, many times. It generally only takes 2-3 cycles to restore a NiMH traction battery to like-new condition. That means if a given hybrid’s battery only needs to be conditioned every 4-7 years, the battery can theoretically outlast the very vehicle it powers and should never need to be replaced.

Click here to find The Hybrid Shop closest to you!

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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Which hybrid battery is better, nickel-metal hydride or lithium-ion?

Which hybrid battery is better, nickel-metal hydride or lithium-ion?

In terms of hybrid battery technology, the lithium-ion battery (Li-ion) is the newcomer. Nickel-metal hydride battery (NiMH) technology has been around for decades and is very reliable chemistry. Regarding various battery chemistries, the key for hybrid vehicles, as well as electric vehicles, is the correct balance between energy density, battery longevity, and power delivery.

The typical sealed lead-acid (SLA) 12 V battery under the hood of a conventional vehicle is very reliable, can deliver loads of power, can be cycled hundreds of times, and lasts for a long time. In a hybrid vehicle, however, an SLA battery would be poorly suited, because it isn’t very energy-dense. In other words, an SLA hybrid battery pack would be so heavy that it would outweigh the benefits of the hybrid powertrain. Just for comparison, the average SLA battery can hold about 35 Wh/kg (watt-hours per kilogram) and deliver about 180 W/kg (watts per kilogram) of power.

Nickel-Metal Hydride

With the introduction of the Toyota Prius, Toyota chose NiMH hybrid battery technology which is far better suited to hybrid vehicle applications. Toyota’s NiMH battery pack holds, depending on model year, up to 46 Wh/kg and can deliver up to 1,310 W/kg power. This energy- and power-density combination enabled the first Toyota Prius hybrid vehicle to achieve 41 mpg. For 2015, Toyota expects to break 55 mpg with the fifth-generation Prius.

Aside from the excellent energy and power capabilities that the Toyota Prius hybrid battery offers, nickel-metal hydride is also a resilient battery chemistry. Typical NiMH batteries can be cycled up to many, many times but will always eventually degrade. If SLA battery performance starts to degrade, the only option is recycling. When an NiMH battery pack begins to degrade, however, it’s still possible to restore its performance, via battery conditioning.


The latest reliable battery chemistry to be developed is lithium-ion, which is already ubiquitous in the world around us, from smartphones to laptops and even electric and hybrid vehicles. Li-ion hybrid battery technology, such as that used in the Ford Fusion Energi plug-in hybrid vehicle, holds about 250 Wh/kg, 7x better than an SLA battery, even 5x better than NiMH, and it can deliver up to 1,000 W/kg.

Additionally, lithium-ion has been proven to cycle at least as well as nickel-metal hydride, a good candidate for hybrid vehicle battery packs. Some newcomers to the hybrid vehicle market are adopting the new technology including different variations of lithium-ion battery technology, such as LCO, lithium-iron phosphate (LiFePO4), and lithium-polymer (LiPo).

Building a “Better” Hybrid Vehicle

While Toyota has held out on making the switch to Li-ion battery types in its hybrid vehicle lineup, except for the Prius Plug-In, it seems that fuel economy and hybrid battery capacity considerations may eventually lead to more Li-on vehicles. But NiMH battery technology will be around for many more years. Li-ion hybrid battery chemistry holds more energy and delivers more power, and seems to be just as reliable as NiMH, which makes it far easier for automakers to justify its adoption.

Still, like all rechargeable batteries, Li-ion hybrid battery performance degrades over time.

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Why is a Ford Escape Hybrid Battery More Expensive than a Standard Battery?

Why is a Ford Escape Hybrid Battery More Expensive Than a Standard Battery?

A common concern for hybrid vehicle owners is the cost of replacing their high-voltage traction batteries. With a reputation for long life and robustness, replacement of the Ford Escape’s battery pack is thankfully rare, but when it does happen, it can cost between $5,000 and $8,000. There are things that owners can do to minimize the need for replacement, such as conditioning and balancing the battery every 4-7 years at The Hybrid Shop for about a third of the cost of replacement. Still, many people are shocked to see the price tags attached to their Escape Hybrid’s battery. After all, it’s just a battery, right?

In fact, the battery pack in the Ford Escape Hybrid, and in most hybrid vehicles, is a large, extremely powerful, extremely complex Nickel-Metal Hydride (NiMH) battery.  There are a number of reasons why it is much more expensive than a traditional Sealed Lead-Acid (SLA) car battery.


The Ford Escape Hybrid’s traction battery pack is comprised of 50 modules, or “sticks,” each composed of five D-cell-sized NiMH battery cells, for a total of 250 individual cells. This compares to just six in an SLA battery. Combined, these 250 cells produce 330 Volts, compared to just 12.6 for an SLA battery. Part of the reason why the Ford Escape Hybrid battery has such a good reputation for longevity is because it is well-cooled. The battery, located beneath the rear cargo area, is encased in an array of fuses and power electronics as well as cooling ducts and fans that draw in cool cabin air to maintain an optimal operating temperature.

Rarity of Materials

More than its complexity and power, however, the greatest contributor to the cost of the Escape Hybrid’s high-voltage battery pack is the fact that manufacturing it requires rare and expensive materials. An SLA battery is made of cheap, readily available materials such as lead, sulfuric acid, and water.

NiMH batteries, on the other hand, are made up of much more expensive materials.  Instead of sulfuric acid, the electrolyte in an NiMH battery is potassium hydroxide.  Instead of lead dioxide, the positive electrodes are nickel oxyhydroxide, which is reasonably inexpensive but still nearly ten times more expensive than lead. The negative electrodes are where the bulk of the cost comes from, though. Instead of sponge lead, the negative electrodes are comprised of an intermetallic compound of rare earth minerals that can include lanthanum, neodymium, cerium, praseodymium, nickel, cobalt, manganese, and aluminum. NiMH hybrid vehicle batteries have been called the largest, single consumers of rare earths in the world.


Finally, the voltage produced by a Ford Escape Hybrid’s battery pack is more than enough to cause serious electrocution and even death. That’s why only an expertly trained technician should service or diagnose it. Only The Hybrid Shop’s technicians have extensive training and the proper equipment to diagnose and replace individual modules of a hybrid vehicle’s battery pack, and only The Hybrid Shop can condition and balance your Escape Hybrid’s battery to keep it healthy and running efficiently for years to come.

Click here to find The Hybrid Shop closest to you!

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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How Long Have Hybrid Batteries Been Around?

How Long Have Hybrid Batteries Been Around?

This is a commonly asked question because of the idea that an older, or more mature, technology is better understood and more reliable. The vast majority of hybrid vehicles on the road today use Nickel-Metal Hydride (NiMH) batteries for their high-voltage traction battery packs. First invented in 1967 and researched over the course of the next two decades by Diamler-Benz, Volkswagen AG, and Philips Laboratories, the first commercially viable NiMH battery, based heavily on lanthanum, was developed in 1987.  Capable of holding more than 84% of its initial capacity over 4,000 full charge-discharge cycles, this technology became commercially available in 1989, and millions of hybrid vehicles are based on this technology today.

In other words, it is a very mature technology, but how well understood is it? With terms such as “memory-effect” floating around, NiMH batteries have gotten something of a poor reputation in some circles. In addition, given that most repair shops, including the dealers themselves, view these battery packs as non-serviceable, “replace or nothing” items, their mystique continues to abound. The truth is, with proper maintenance and usage, NiMH batteries are the longest-lasting, most reliable high-energy rechargeable batteries available today — providing an optimal combination of energy density, safety, and abuse-resistance for the needs of most hybrid vehicle designs.

What About Memory-Effect?

The mysterious so-called “memory-effect” is nothing more than a natural chemical reaction within the battery when used in a shallow-cycle mode (such as in hybrid vehicles) that allows a resistive layer of crystals to form on the surface of the nickel electrodes. With modern technology, this layer develops very slowly, and NiMH performance degrades reversibly over a period of time (typically 4-7 years) with typical usage. By discharging a NiMH battery pack to a 0% state-of-charge, and charging it to 100% (called a cycle), and then repeating that cycle one or more times, the resistive layer can be broken up, restoring the battery’s capacity, performance, and life expectancy to between 90% and 95% of what it was when new. This is called Conditioning.

In most cases, battery conditioning can revitalize a Nickel-Metal Hydride battery pack for a fraction of the cost of a new replacement battery at the dealer, allowing a vehicle owner to continue to use their existing battery, while restoring vehicle performance and gas mileage.

If performed as part of a vehicle’s preventive maintenance regimen every 4-7 years (or 60,000 to 100,000 miles for most drivers), it is entirely possible that a hybrid vehicle’s NiMH traction battery could outlast the vehicle itself and would never need to be replaced. This not only saves thousands of dollars and keeps the car running at peak performance and fuel efficiency, it also keeps hard-to-recycle battery packs out of the waste stream and prevents wasting precious natural resources to construct unneeded new battery packs.

Click here to find The Hybrid Shop closest to you!

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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When does the engine take over for the motor in the Hyundai Sonata Hybrid, and can I change it?

When does the engine take over for the motor in the Hyundai Sonata Hybrid, and can I change it?

As with all hybrid vehicles, the Hyundai Sonata Hybrid is equipped with two power sources. Despite looking visually identical to the non-hybrid version, the hybrid version is powered by both a 2.4 ℓ four-cylinder internal combustion engine (ICE) and an electric motor generator (MG). The MG is mounted in place of the torque convertor, directly attached to the six-speed automatic transmission. In that, we note that the Sonata Hybrid drives and feels like any conventional automatic-transmission vehicle, with the exception of the input power switching between the ICE and MG, depending on demand.

Unlike many hybrid vehicles, however, there is no dedicated EV-Mode (electric vehicle mode) switch, but taking note of the power split screen on the center console gives us a good idea of when the Hyundai Sonata Hybrid is making use of the ICE and MG. Depending on driver demand, vehicle speed, and a few other factors, one or the other, or both, may be powering the transmission at any one time. However, the Sonata Hybrid does tend to favor the MG over the ICE when it can.

Shift points and power splits

The Hyundai Sonata Hybrid’s six-speed automatic transmission determines which gear to select depending on how much power and speed is being requested by the driver. The hybrid controller likewise determines how to power the automatic transmission based on the same factors. Light to moderate acceleration typically occurs in EV-mode and, depending on battery SOC (state-of-charge), can max out at 75 mph. Many drivers report their Sonata Hybrids stay in EV-Mode from zero to between 30 mph and 50 mph. This is the most efficient power, from about zero to 40 mph, as the MG generates its maximum torque of 151 lb•ft below 1,630 rpm.

The hybrid controller may engage the ICE as low as 1 mph for hard acceleration and hill climbs, but drivers typically report the ICE engaging anywhere between 20 mph and 50 mph. In doing this, the hybrid controller takes advantage of the torque that the ICE doesn’t begin to develop until around 2,500 rpm, maxing out at 151 lb•ft at 4,500 rpm. While cruising, the hybrid controller may engage and disengage the ICE and MG, depending on energy demands and hybrid battery SOC. During deceleration and at a stop, the MG switches to generator mode, disengaging from the ICE. This provides engine braking and charges the 270 V 47 kW lithium-polymer hybrid battery. Also, whenever the SOC drops, the ICE engages the MG to charge the hybrid battery.

No Drive Modes

Unlike some other hybrid vehicles, though, the Hyundai Sonata Hybrid doesn’t have a dedicated EV-Mode switch or any other Mode switches, such as Eco-Mode, Normal-Mode, or Power-Mode. That being said, the Hyundai Sonata Hybrid is hard-wired, but still highly dependent on driver input. Power split modes may be slightly affected if you use the automatic transmission in manual mode. If you drive it easy, the hybrid controller will engage EV-Mode more often and stay engaged longer, but, if you drive it hard, the hybrid controller will engage the ICE sooner and keep it engaged longer.

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Are There Different Kinds of Hybrid Batteries?

Are There Different Kinds of Hybrid Batteries?

There are two main types of high-voltage traction batteries used in hybrid electric vehicles today, each with its own advantages and disadvantages. By far the most common type is Nickel-Metal Hydride (NiMH). Many plug-in hybrids and electric vehicles use Lithium-Ion (Li-Ion) batteries instead, even though it is a newer and less-proven technology for vehicle applications. This is because Lithium-Ion batteries have much greater energy density, or energy per unit mass. This means for a given energy requirement, they are lighter. In an electric vehicle or plug-in hybrid vehicle, which requires enormous amounts of reserve power, the weight differential can result in extended range and improved efficiency.

Despite this, the Li-Ion batteries aren’t widely in use in normal hybrid vehicles for several reasons. The first is because they are dangerous. They contain a flammable electrolyte because water-based electrolytes don’t have high enough conductivity for the voltage produced by a single cell of a Li-Ion battery. They also swell when in a high state-of-charge, so to keep the swelling under control, Li-Ion batteries are kept under pressure. For consumer electronic applications, this isn’t too great a concern, because they aren’t typically used in conditions which could cause them to rupture, plus the low power needs of portable electronics means that their batteries are small. The battery pack in an electric or plug-in hybrid vehicle, on the other hand, is very large, and there is a chance that it could eventually be subjected to rupturing conditions such as a vehicle collision.

Nickel-Metal Hydride batteries have lower energy density than Li-Ion batteries but are still much better than most other battery technologies. They are much safer than Li-Ion batteries and are more abuse-resistant, using a water-based electrolyte that isn’t flammable or pressurized. They can also last much longer, in terms of calendar life, if they’re treated well and properly maintained through a process called conditioning. Aside from their marginally lower energy density, their primary disadvantage for automotive applications is a much higher rate of self-discharge, up to 30% per month compared to 1.5% for Li-Ion. This means a hybrid vehicle with a NiMH traction battery pack needs to be driven frequently, preferably daily, as the battery doesn’t like to sit for long periods of time.

Battery Service Options

The Hybrid Shop’s expertly trained technicians are fully fluent in both types of battery technology. Unlike a dealer, which views a vehicle’s battery as a mysterious black box to be wholly replaced or left alone according to what a computer tells them, The Hybrid Shop can perform a detailed State-of-Health analysis of a hybrid’s battery, testing the energy, power,  and state-of-charge for each individual module. This allows for individual damaged cells to be replaced at a large saving over the cost of a new battery.

For Nickel-Metal Hydride batteries, The Hybrid Shop also offers proprietary, one-of-a-kind battery conditioning service. For all hybrid batteries, the strength of the pack is limited to the strength of its weakest cell, so as a battery goes out of balance, with its various cells and modules providing different amounts of energy or power, only the weakest cell’s capacity matters. By balancing the cells to each other and by breaking up the resistive layer that forms on the nickel over time, battery conditioning can restore 90%-95% of a NiMH battery’s power and energy and increase life expectancy for between a third to half the cost of a replacement battery pack.

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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Are There Problems With a Hybrid Battery That I Could Fix Myself?

Are There Problems With a Hybrid Battery That I Could Fix Myself?

The short answer is simple: No.

Even the dealer’s technicians do not consider a hybrid vehicle’s high-voltage or traction battery to be a serviceable item. They aren’t trained or equipped to go any deeper into its diagnosis than to talk to the car’s primary computer, the Hybrid Controller, to see if it’s detected a catastrophic failure. If it has, they replace the entire battery, often needlessly. If it hasn’t, they leave it alone, even if there are problems causing decreased performance and fuel economy.

Despite that, some people really like the DIY mentality and want to try to fix their vehicles themselves. Cars are dangerous things. They’re big, heavy, and filled with a wide variety of chemicals, many of which are flammable, toxic, irritating to the skin, or worse. Even so, a conventional automobile’s risks are understood by many people and can be managed by an adventurous owner with a moderate amount of technical skill. With a hybrid vehicle, though, that simply isn’t the case. Let’s discuss just a couple of the reasons.

High-Voltage, High-Energy Systems Mean High Electrocution Risk

A hybrid electric vehicle’s high-voltage power cables are covered in bright orange insulation for a reason. It’s a warning to stay away — a warning that should be heeded — it’s a high-voltage system after all.

Physics 101: Ohm’s Law states that Current = Voltage over Resistance (I=V/R)  

The human body has a resistance between 1,000Ω and 100,000Ω depending on a variety of conditions. For direct current (DC), the type of current that flows through a hybrid’s high-voltage systems, the amount of current that can cause fibrillation of a person’s heart, and subsequent death without immediate medical attention, is about 300mA. Unfortunately at 88mA, muscles contract involuntarily, making it impossible to let go of the source of the current.

A conventional car battery produces 12.6 volts when fully charged. Since most people would consider death to be an unacceptable risk, we’ll use the worst case of 1,000Ω of resistance.  Thus, the most current you can expect to experience when touching both terminals of your car’s conventional sealed lead-acid battery, is I = 12.6V / 1,000Ω, or 12.6mA. This is just enough that you might feel a slight tingling sensation in your hands and fingers. On a dry day you won’t even feel that. So it’s safe, electrically speaking, for an adventurous car owner to work on a conventional vehicle’s electrical systems.

A hybrid vehicle’s traction battery, on the other hand, produces much higher voltage. For argument’s sake we’ll use the most commonly-serviced hybrid, the Second Generation Toyota Prius produced between 2004 and 2009. The Prius’ battery produces 201.6V of electrical potential. In the same scenario as above, that means the current you can expect to experience is 201.6mA, more than enough to ensure that you can’t let go once you’ve grabbed the battery or a damaged cable. “But wait,” you say, “That’s less than the 300mA required to stop my heart!” Ah, but it’s not that simple. Since you can’t let go, the current will begin to damage the skin, burning it, which can reduce its resistance to as low as 500Ω. At 500Ω, now you’re experiencing 403.2mA, more than enough to kill you. This is just one reason you should always bring your hybrid vehicle to a qualified repair shop, such as The Hybrid Shop, any time its high-voltage components need servicing.

Safety First – Bring Your Hybrid to a Qualified Technician For All Repairs

Electrocution aside, hybrid vehicles are more dangerous to service than conventional ones for other reasons too. For example, just because a hybrid’s Internal Combustion Engine (ICE) is off, doesn’t mean it’s safe to work on. There are a number of conditions in which the vehicle’s Hybrid Controller turns the gasoline engine off, but the vehicle itself is still fully active. This means that if the Hybrid Controller decides it’s necessary, it can restart the ICE without warning. If you happen to have your hand in its workings, or are beneath it with the oil filter off, this could pose various health risks.

While the dealer is certainly qualified to perform most repairs on your hybrid vehicle, only The Hybrid Shop can perform in-depth diagnosis of the State-of-Health of your hybrid’s high-voltage systems, including the battery, motor generator, power converters, and more.  And, for a third-to-half the cost of battery replacement, The Hybrid Shop’s technicians – the most highly trained in the world to work on your hybrid vehicle – can condition your battery using a scientifically proven process, allowing you to reuse it in like-new condition for years to come.

Click here to find The Hybrid Shop nearest you today!

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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Where would I find hybrid training to work on a Subaru XV Crosstrek Hybrid?

The Subaru XV Crosstrek Hybrid May Have Come Late to the Market, but Subaru Nailed It.

Compared to other automakers, such as Toyota, Subaru may have been one of the latecomers to the hybrid vehicle market. In fact, whereas Toyota released its first Toyota Prius back in 1996, Subaru waited nearly two decades before implementing the technology in any of its vehicles. Because Subaru enthusiasts are such a unique group, one might even say finicky, “getting it right” was tops on Subaru engineers’ priority list. Well the wait has been worth it. Their first-ever hybrid vehicle, the 2014 Subaru XV Crosstrek Hybrid, for lack of a better phrase, nails it.

Subaru’s current conventional lineup is typified by four-cylinder boxer engines, constant velocity transmissions (CVT), and all-wheel drive, and the 2014 Subaru XV Crosstrek Hybrid adds an electric motor generator (MG) and a small hybrid battery pack. Under the hood of the Subaru XV Crosstrek Hybrid, aside from all the familiar components, is the light-hybrid system consisting of a 10 kW electric motor generator, built into the back of a modified version of Subaru’s Lineartronic CVT. The MG is powered by, and recharges, a 600 Wh 100 V NiMH (nickel-metal hydride) hybrid battery hidden under the floor of the cargo area where the spare tire would be located in the non-hybrid version.

How Much Training do I Need to Work on a Subaru XV Crosstrek Hybrid?

As an automobile technician, or even a do-it-yourselfer, you might wonder what it takes to work on the Subaru XV Crosstrek Hybrid. Given some basic training, it takes surprisingly little, because the Crosstrek Hybrid is actually not much different from its non-hybrid sister vehicle.

Practically everything is the same about the vehicle, except for the addition of an MG-equipped CVT, hybrid battery pack, and hybrid vehicle controller. Aside from that, all other services remain the same, including engine maintenance, brake service, and 12 V electrical system, to name a few. On the other hand, if a Subaru XV Crosstrek Hybrid has fuel economy or performance issues, you’ll need some advanced training.

Where Do I Find Advanced Hybrid Training?

Understandably, the addition of hybrid elements makes the system more complex, especially the interaction of the MG with the CVT, so problems with acceleration and fuel economy need to take into account the hybrid system. Hybrid training is provided by Subaru for Subaru Master and Senior Master Technicians and requires years of experience and dedication. Fortunately, with the right attitude and a job at a Subaru Service Center, the training is free. Even more advanced than Subaru’s own hybrid training program, though, is The Hybrid Shop’s advanced hybrid training program.

With the right attitude, years of experience and dedication, and a job at The Hybrid Shop, this training is also not only free, but it is much deeper than anything else available. The Hybrid Shop’s approach to hybrid vehicle maintenance, diagnosis, and repair is based on decades of hybrid and electric vehicle research and development. The Hybrid Shop technicians are trained to understand and work on hybrid vehicles, such as the Subaru XV Crosstrek Hybrid, with greater knowledge and depth than any other technicians. Their expertise includes thorough analysis of the engine, transmission, electric motor generator, and the hybrid battery, and the result is more accurate diagnosis, typically less-expensive repairs and, ultimately, greater customer satisfaction.

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Do I need a technician with hybrid training to fix my Ford Fusion Energi?

Do I need a technician with hybrid training to fix my Ford Fusion Energi?

No matter what kind of vehicle you drive, it will eventually require service. If you want to keep your car running well, you’ll need regular service, at least every 5,000 to 10,000 miles. The question is, “Does my hi-tech Ford Fusion Energi require a technician with hybrid training to work on it?” The answer is, of course, “It depends.”

We have to remember that any hybrid vehicle, such as the Ford Fusion Energi plug-in hybrid electric vehicle, is a combination of conventional vehicle components and electric vehicle components, hence the “hybrid” designation. Like all conventional vehicles, the Ford Fusion Energi has tires, wheels, brakes, a 12 V electrical system, an internal combustion engine (ICE), exhaust system, air conditioning system, suspension, steering, and body, to name a few.

On the other hand, the Ford Fusion Energi’s hybrid system includes a 7.6 kWh 310.8 V lithium-ion hybrid battery and 88 kW (118 hp) worth of electric motor generators (MG), mounted in an eCVT (electronically-controlled constant velocity transmission). Additionally, a power control unit (PCU) controls the flow of energy between the hybrid battery, charging system, MGs, and 12 V electrical system.

One-Half of the System

Whether your Ford Fusion Energi requires a technician with hybrid training or not depends entirely which half of the vehicle he’s working on. For non-hybrid-trained technicians, the only rule is to avoid touching the orange cables and other high-voltage hybrid components. Otherwise, there’s really nothing different about his job. Changing the oil or air filter for the ICE, or even replacing a radio, would be practically no different than on a conventional vehicle and would require no special training or safety precautions.

On the other hand, any work involving hybrid vehicle components would definitely require the technician to have hybrid training and proper equipment. To protect himself from the high-voltage battery in the Ford Fusion Energi, the technician needs to use insulating rubber gloves and know how to safely isolate the hybrid battery and discharge the rest of the hybrid system before working on it.

The Hybrid System

Of course, proper diagnosis and repair of a component in the Ford Fusion Energi hybrid system requires hybrid training. Because of the hybrid nature of the Ford Fusion Energi, addressing fuel economy and performance problems isn’t limited to just the ICE but to the MGs, PCU, and hybrid battery as well.

Dealership technicians do receive hybrid training from the automakers they service, mostly limited to remove and replace operations to address specific diagnostic trouble codes or catastrophic failures. Addressing hybrid vehicle performance and fuel economy issues, especially after warranty, could very well prove to be prohibitively expensive if addressed in this manner.

The Hybrid Shop, on the other hand, has the hybrid training to go deeper into the system than even dealership technicians. The Hybrid Shop technicians understand the delicate balance between the ICE, MGs, PCU, and hybrid battery, so they can properly address any customer concerns with hybrid vehicle performance and fuel economy. Even the hybrid battery itself can be repaired, and The Hybrid Shop can restore hybrid battery performance without resorting to expensive replacement.

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What is a Ford Escape Hybrid battery made of?

What is a Ford Escape Hybrid battery made of?

Until the introduction of the Ford Fusion Hybrid, the Ford Escape Hybrid was Ford Motor Company’s first and most popular hybrid vehicle. Considered a parallel hybrid vehicle, it is powered by a combination of a traditional internal combustion engine (ICE) technology and electric motor generators (MGs). The 2.3 ℓ Atkinson-cycle four-cylinder ICE generates 133 hp, and the MGs are rated at 70 kW, for total system output of 228 hp (168 kW). In spite of this moderate power output, the Ford Escape Hybrid gets as much as 32 mpg (miles per gallon), one of the best in crossover SUV fuel economy on the market.

While the ICE, of course, gets its energy from the fuel tank, the MGs get their energy from the hybrid battery pack. Hidden under the rear floor of the Ford Escape Hybrid is a high-voltage battery pack, which weighs about 110 lb (50 kg). It is a complex arrangement of nickel-metal hydride (NiMH) rechargeable battery cells, which most of us would recognize as a basic “D”-size battery, each rated at approximately 1.3 V. Five individual cells are soldered and shrink-wrapped together to form a five-cell module, and a total of fifty of these modules are connected in series in the hybrid battery pack. The hybrid battery, as a whole, has a nominal capacity of 5.5 Ah at 330 V.

Much like the SLA (sealed lead acid) battery under the hood of conventional vehicles, the hybrid battery in the Ford Escape Hybrid holds a charge for future use in the vehicle. Since the SLA battery only needs to start the engine and run accessories for a short time, it doesn’t need a whole lot of capacity. On the other hand, NiMH battery chemistry can hold as much as four times the energy per kilogram than SLA battery chemistry, which makes it a good choice for hybrid battery application.

Why does Ford Escape Hybrid fuel economy and performance wane?

With proper maintenance, the ICE will perform pretty much the same over its lifespan, which may be well over 250,000 miles. The MGs, however, may begin to lose their effectiveness over time, perhaps in as little as 60,000 miles. Because with the exception of battery conditioning there is essentially no maintenance that can be done to an MG. Why would the Ford Escape Hybrid’s fuel economy and performance suffer over time? The problem is that the hybrid battery starts to go out of balance and lose power and capacity.

Recall that the hybrid battery pack is actually made of 250 individual NiMH cells, and each of them ages differently. Just as a chain is only as strong as its weakest link, the hybrid battery pack only performs as well as its weakest module. For example, each five-cell module is designed to hold 6.6 V, but over time it may be weakened to the point where it can only hold 6.0 V or worse. Its neighbor module may only be able to hold 5.5 V, and some others may actually be able to hold 6.8 V. On the whole, however, the hybrid battery pack may only hold 300 V, when it is designed for 330 V. This reduces the performance of the entire vehicle.

While hybrid battery pack rebuilding or replacement may seem like the only resolution, The Hybrid Shop has a cost-effective alternative. Hybrid battery conditioning can restore the Ford Escape Hybrid battery to near-factory performance, voltage, and capacity, without resorting to expensive replacement or unreliable rebuilding procedures. Fuel economy and performance are restored, at a fraction of the cost of hybrid battery replacement or rebuilding. Additionally, unlike hybrid battery replacement or rebuilding, battery conditioning keeps hard-to-recycle NiMH battery components out of the waste stream.

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Do Toyota Camry Hybrids Have Models with Manual Transmission?

Do Toyota Camry Hybrids Have Models with Manual Transmission?

The greater fuel economy of hybrid electric vehicles such as the Toyota Camry Hybrid makes them desirable for environmentally-conscious and frugal consumers alike. Still, some drivers  want the thrill or the extra control of shifting a vehicle’s transmission manually. Unfortunately for them, “full hybrid” vehicles can’t accommodate a clutched manual transmission. A “mild hybrid” could be designed with a manual transmission, but most still use automatics due to their popularity and efficiency. In fact, the only manual hybrid on the market through the 2015 model year is the Honda CR-Z, getting three mpg less fuel economy than the automatic version of the same model.

What’s the Difference Between Full and Mild Hybrids?

A “full hybrid” is defined as a vehicle that can operate with any combination of gasoline or electric power. For example, a Toyota Camry Hybrid or Toyota Prius can operate purely on electric power at low speeds under gradual acceleration, with the internal combustion engine (ICE) completely off. It can even travel for several miles when out of gas to reach a service station. When traveling at highway speed, all, or almost all, of the power comes from the ICE, with the electrical system supplying power to the vehicle’s electronic accessories and charging the high-voltage traction battery. During hard acceleration or at moderate speed, power from the ICE and electric motors is seamlessly blended to provide the power and torque demanded by the driver.

A “mild hybrid” is more like a conventional vehicle’s drivetrain. The ICE is always engaged to the powertrain through a traditional automatic or manual transmission and can’t be turned off during driving, just like in a normal car. The electric motor is integrated with the ICE and takes the place of the flywheel, providing assistance to the ICE for added torque in high-acceleration situations. That’s why Honda calls its system Integrated Motor Assist.

Most Full Hybrids Don’t Include a Traditional Transmission At All

The majority of hybrid vehicles on the market, including the Camry Hybrid, actually don’t include discrete, selectable drive ratios at all. Toyota’s Hybrid Synergy Drive, which has been licensed to or closely modeled by most other manufacturers of hybrid vehicles, is what’s called an electronic continuously variable transmission, or e-CVT. Without getting into too much technical detail, this type of powertrain uses a unique application of a single planetary gear to split power between the ICE, a small electric motor-generator called MG1, and a larger motor-generator called MG2.

MG1 normally acts as a generator, absorbing unneeded power from the ICE and using it to power the vehicle’s electronic systems, charge the traction battery, and transfer some of the ICE’s power to MG2. It acts as a motor only to start the ICE and during a special mode of braking meant for long, steep descents, in which MG2 spins the ICE with the throttle closed, to perform traditional engine braking

MG2 is the primary electric motor that helps drive the car, accepting power from MG1 or the traction battery as needed. It is also the regenerative braking unit, acting as a generator to slow the vehicle under gradual braking, sending the recaptured energy to the traction battery to charge it.

As in other types of continuously variable transmissions, the e-CVT allows the ICE to run at its optimally efficient RPM range for a given demand of power and torque placed on it. Because the ICE’s low torque at low vehicle speeds is augmented by MG2, and its excess power produced at moderate and high vehicle speeds is absorbed by MG1, there is no need to change the ICE’s drive ratio and no need to swap in different gear systems, manually or otherwise.

Copyright 2014 The Hybrid Shop, LLC. All Rights Reserved

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How much does it cost to have a 2013 Ford Fusion hybrid transmission replaced?

How much does it cost to have a 2013 Ford Fusion hybrid transmission replaced?

The Ford Fusion Hybrid has become one of America’s most popular mid-size sedans, thanks in part to its bold styling, roomy interior, and comfort and convenience options. Add in exceptional fuel economy at a great price point, and the Ford Fusion Hybrid is a convincing competitor for our transportation dollar. While the 2013 Ford Fusion Hybrid looks just like the conventionally-powered Ford Fusion sedan, under the hood is quite different. The 2013 Ford Fusion Hybrid, as well as the plug-in hybrid Fusion Energi, for that matter, is powered by a 2.0 ℓ four-cylinder gasoline engine in combination with an electric motor generator (MG). The MG is powered by, and charges, a lithium-ion battery pack.

The motor generator is an integral part of the electronically-controlled constant velocity transmission (CVT) which Ford chose for its superior fuel economy benefits. Unlike a traditional automatic transmission, which may have anywhere from four to eight, or as many as ten, fixed gear ratios, a CVT has an infinite number of gear ratios, perfectly matching engine speed to driver demand. Given that the CVT is an integral part of the 2013 Ford Fusion Hybrid, it stands to reason that any performance or fuel economy problems might be traced to it, but it isn’t that simple.

Transmission Replacement Costs

In case of shuddering, poor acceleration, or abnormal transmission noises, diagnosis might point to a fault in the CVT, which is typically a remove-and-replace operation. Pricing for the transmission alone comes to about $4,800, which doesn’t include a few hours’ labor and miscellaneous fluids. All told, replacing the 2013 Ford Fusion Hybrid CVT might cost somewhere in the neighborhood of $5,500 to $6,000. The question becomes, “Is replacement the only option?”

Whereas a Ford service center only sees the CVT as a non-serviceable unit, The Hybrid Shop is trained and equipped to work at the component level, including both electrical and mechanical components. For example, while the MG has no moving parts in itself, it is mounted in the CVT using standard roller and needle bearings, which can wear out over time and cause noise and balance problems. The Hybrid Shop technicians can replace bearings that have worn out, restoring MG balance and quietness. As another example, while the copper windings in the MG are typically not a failure point, it isn’t unheard of, and The Hybrid Shop can test the MG for integrity, replacing just the failed part instead of the whole transmission unit.

A Thorough Diagnosis

A thorough diagnosis by The Hybrid Shop, including evaluation of the engine, motor generator, transmission, and hybrid battery performance, on the other hand, can reveal where the fault lies with any 2013 Ford Fusion Hybrid problems. Issues with fuel economy or performance may have nothing to do with the CVT but rather with the lithium-ion hybrid battery pack, which is a common failure point in every hybrid vehicle.

The hybrid battery is made up of a number of individual modules and cells, each of which ages at different rates. Over time, the battery can become unbalanced, resulting in less energy available to power the MG in the transmission. Hybrid battery conditioning by The Hybrid Shop can restore hybrid battery performance to near-factory specification, restoring fuel economy and performance without resorting to unnecessary and expensive hybrid battery or CVT replacement.

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How is a Ford C-MAX hybrid battery different from a regular battery?

Most people can readily identify a “regular” automobile battery, the 12 V sealed lead acid (SLA) battery in practically every conventional automobile on the road today. There are variations in voltage, size, and construction, depending on application, but they are all essentially lead-acid chemistry. The typical SLA battery weighs between 10 kg and 20 kg, and open circuit voltage is usually around 13.5 V.

The hybrid battery in the Ford C-MAX Hybrid is very different, in more ways than one. For starters, the battery pack weighs about twice that of the typical SLA battery, just 34.5 kg, yet is rated at 281.2 V and holds 1.4 kWh (kilowatt-hours). What really sets the hybrid battery apart is its chemistry, commonly referred to as lithium-ion (Li-ion), specifically Lithium Nickel Manganese Cobalt Oxide (LiNixMnyCozO2), NMC for short, in the case of the C-MAX.

Energy Density: SLA vs Li-Ion

The main difference between these two battery types is energy density, that is, how much energy each battery type can hold, which is directly related to how long a device will run off the battery. Ford C-MAX Hybrid’s NMC battery is about eight times more energy-dense than the typical SLA battery, wherein lies its advantage.

In a conventional vehicle, the only purpose for the SLA battery is to start the ICE (internal combustion engine) and maybe run a couple of accessories for a short time, so it doesn’t need to hold a lot of energy. After providing the short burst of power to start the ICE, the generator provides power for running the vehicle electrical system. The typical SLA battery ranges in energy density from 30 Wh/kg to 40 Wh/kg (watt-hours per kilogram).

However, because the electrical load in a hybrid vehicle is so much higher, including not only the vehicle electrical system, but also the MGs (electric motor-generators) that move the vehicle, the Ford C-MAX Hybrid battery needs to hold significantly more. In reverse and stop-and-go traffic, the ICE may not run at all, unless the battery needs to be recharged, all the while using the hybrid battery for motive power and the electrical system.

The NMC hybrid battery in the Ford C-MAX has an energy density of about 200 Wh/kg at 20x the voltage, holds 1.4 kWh and weighs 34.5 kg. To hold the same amount of energy in an SLA battery pack, the pack would need to weigh nearly 200 kg, effectively canceling out any fuel economy benefits of the hybrid powertrain.


Finally, the Ford C-MAX Hybrid battery is a lot more complex than the typical SLA battery. While an SLA battery is made up of six 2.1 V cells, the C-MAX hybrid battery is made up of 76 NMC cells, each producing 3.7 V, along with temperature sensors and voltage monitoring sensors. While most any technician can replace an SLA battery for a couple hundred dollars, special training is required to determine the health of the hybrid battery, the replacement of which may cost thousands of dollars. On the other hand, the Ford C-MAX Hybrid battery typically doesn’t “fail” as a unit.

More often than not, one or two modules may be out of balance with the rest of the pack, dragging down the performance of the pack as a whole, leading to poor hybrid vehicle performance and fuel economy.  The Hybrid Shop can restore a Ford C-MAX Hybrid battery to as much as 95% of factory condition without replacing any parts, restoring hybrid vehicle performance and fuel economy, at a fraction of the cost of hybrid battery replacement.

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Is it less expensive to recondition a hybrid battery than buy new?

Is it less expensive to recondition a hybrid battery than buy new?

As the term suggests, buying a “new” hybrid battery is exactly the same thing as what comes in a new hybrid vehicle. Constructed of entirely new rechargeable battery modules, bus bars, temperature and voltage sensors, a new hybrid battery pack will perform just as good as the original one that came in the car to begin with. Still, buying a new hybrid battery can cost between $5,000 and $10,000, depending on make and model, which makes less-expensive reconditioned hybrid batteries an attractive proposition.

Reconditioned hybrid battery packs, also referred to as rebuilt or remanufactured, are typically tested for proper operation, and defective or worn components, such as degraded battery modules or burnt-out temperature sensors, are replaced with new ones. Since most of the battery pack is original, a reconditioned hybrid battery can be significantly less expensive than a new one, but is it all it’s cracked up to be?

Reconditioned Hybrid Battery Packs: Two Caveats

While a new hybrid battery is guaranteed to perform as expected, this is only because it’s constructed of all new parts. Reconditioned hybrid battery pack performance can be sketchy, if you consider what it is the rebuilder actually does. Ostensibly, each battery module would be tested for power delivery and capacity, and replacements would be ordered for those that aren’t up to task. Unfortunately, a simple voltage test or ten-second health check isn’t enough to determine a module’s health. So, there’s the first caveat: that individual hybrid battery pack modules may or may not be well-balanced with the rest of the pack.

The second caveat is that the source of replacement modules may be questionable. Early in the hybrid vehicle revolution, manufacturers, such as Honda and Toyota, weren’t very careful with their hybrid battery pack return policies, so there were many of these “spent” hybrid battery packs floating around the market. Eventually, these companies started imposing huge core charges, to make sure the packs would end up back at the manufacturer. Today, regarding Honda five- and six-cell “sticks,” or modules, there are just one or two suppliers out of China, whose quality and manufacturing standards may or may not be up to par.

When hybrid vehicle performance or fuel economy begins to suffer, or if this has gone on so long that the hybrid controller has detected a major fault and shut the system down, a shop may suggest hybrid battery replacement, at which point you’re left with the two choices above. On the other hand, The Hybrid Shop offers an alternative — hybrid battery conditioning.

Hybrid Battery Conditioning

The Hybrid Shop can often restore a hybrid battery to over 90% of its factory performance and capacity, without throwing away any parts, for a significant cost savings.

During initial testing, if an individual module requires replacement, the process moves to rebuilding, after which the pack is conditioned to ensure that all modules are contributing equally to the pack. After all, the hybrid battery pack is only as strong as its weakest module, so leaving out the conditioning process is essentially a gamble.

Finally, hybrid battery conditioning by The Hybrid Shop is covered by a twelve-month unlimited-mileage guarantee, unlike some refurbished hybrid batteries, which may carry as little as a thirty-day guarantee, if any at all.

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What are common problems with early Honda Civic hybrid batteries?

What are common problems with early Honda Civic hybrid batteries?

Hybrid vehicles, consisting of both fossil fuel and electrical components, deliver better performance and fuel economy simply by virtue of combining the best attributes of both the internal combustion engine (ICE) and the electric motor-generator (MG). The energy for the ICE is stored in the fuel tank and, because it is refillable in just a few minutes at the gas station, it doesn’t really degrade. Of course, regular maintenance of the ICE will assure continued reliability, performance, and fuel economy. The energy for the MG is stored chemically in the hybrid battery pack, which has a limited lifespan, perhaps five to seven years, before its performance begins to degrade.

Honda hybrid vehicles have been around since the beginning of the hybrid vehicle revolution, nearly twenty years ago. The average lifespan of a Honda Civic hybrid battery is most directly related to how and where it is driven. That is to say, a hybrid vehicle is best driven daily in stop-and-go traffic in a temperate climate. Honda’s hybrid control system, called Integrated Motor Assist (IMA), suffered from its own design for the first couple of generations, leading to many premature failures, service programs, and even class-action lawsuits.

Heat kills hybrid batteries

As mentioned, a temperate climate is the best for promoting long hybrid battery life, so a Honda Civic hybrid battery pack will last longer in Boston than it will in Dallas. The main enemy is heat, and different hybrid automakers have different approaches to maintaining optimum temperature in the battery pack. Early Honda hybrid battery packs were air-cooled, however insufficiently, creating an artificially-induced hot climate.

The problem is that the chemical reactions in a nickel-metal hydride (NiMH) battery, as with all batteries, are dependent on temperature. Higher temperatures generally mean better reaction times, which explains why a warm battery delivers better power than a cold battery, but only to a certain limit. The old SLA (sealed lead acid) rule, “double the temperature, half the lifespan,” applies just as well to poorly-cooled hybrid batteries of NiMH chemistry. Higher temperatures can lead to “thermal-runaway,” that is, the chemical reactions race out of control, which leads to premature aging, electrolyte leakage, and possibly even fire.

The Hybrid Shop’s holistic solution

If the IMA light has come on, typically reflecting a fault in the Honda Civic Hybrid IMA Battery system, one or more modules may be the root cause of the problem. Hybrid battery replacement may, indeed, solve the problem caused by a couple of overheated and compromised modules, but it is an expensive and possibly unnecessary step. Additionally, simple replacement, even with an updated controller and battery pack, doesn’t address the cooling problem, which puts the new battery pack in the same compromised position as the old one. What is needed is an overall approach, such as that offered by The Hybrid Shop.

The Hybrid Shop can determine which modules have failed, replacing just the failed modules. This is referred to as hybrid battery rebuilding or refurbishing, after which the hybrid battery goes into the conditioning stage. During hybrid battery conditioning, individual modules are carefully discharged and recharged, resulting in a well-balanced hybrid battery pack. Finally, upon installation, The Hybrid Shop installs a fan kit which effectively reduces the IMA battery pack’s temperatures by between 12 °F and 20 °F, keeping the battery pack within safe limits. The entire process costs far less than full replacement and addresses the cooling problem, ensuring more years of reliable service, performance, and fuel economy.

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How long does a Toyota Prius hybrid battery last?

How long does a Toyota Prius hybrid battery last?

Every part of a hybrid vehicle, just as in a conventional vehicle, is “living on borrowed time,” so to speak. Over months and miles, every part of the car eventually wears out, some parts faster than others. For example, tires and brakes can “last” anywhere from 20,000 to 80,000 miles, depending on climate and driver habit. Toyota engines, for example, are designed for at least a 250,000-mile lifespan. With proper maintenance, we’ve seen plenty of Toyotas with two- or three-times this mileage.

When it comes to hybrid vehicles, such as the Toyota Prius, most of the same rules apply, except that brake pads and the engine tend to last longer because they are used less than in conventional vehicles. In addition to the conventional vehicle components, however, there are also the hybrid vehicle components, including the electric motor generators, power control unit, and hybrid battery. Seeing as the Toyota Prius is one of the oldest hybrid vehicles on the road, it seems fit to ask, “How long does the hybrid battery last?”

Climate and driver habit

Most parts of the Toyota Prius hybrid vehicle are accessible for maintenance only by a technician, including tires, brakes, and engine. On the other hand, only driver habit has a direct effect on the health of the hybrid battery. While the driver doesn’t have direct access to the hybrid battery pack, his habits have the most impact on lifespan. Put simply, hybrid vehicles are best driven daily, with a good mix of stop and go traffic, and in a temperate climate.

Under the best circumstances, the Toyota Prius hybrid battery should perform well for five to seven years, mileage being much less of a consideration than in conventional vehicles. Given that the average American drives 11,500 miles-per-year, five to seven years on a Toyota Prius hybrid battery is somewhere between 60,000 and 80,000 miles, after which drivers may begin to experience declining performance or fuel economy.

This doesn’t mean, however, that the hybrid battery will simply die at 81,000 miles, disabling the vehicle. Drivers may easily get up to twelve years and 200,000 miles before the hybrid controller determines hybrid battery performance is so far gone that it can’t use it anymore. A first-generation Toyota Prius’ poorly performing hybrid battery, for example, could be impacting fuel economy and performance in a big way. The 2001 Toyota Prius is rated at 42 mpg (miles per gallon) city, but could deliver as little as 30 mpg with a “spent” hybrid battery. Hybrid battery replacement may seem to be the best answer, but hybrid battery conditioning is an even better answer.

Hybrid battery conditioning

In the case of a first-generation Toyota Prius, hybrid battery replacement may cost as much as $5,000. Battery conditioning, however, may cost as little as $1,500. Battery conditioning uses the original hybrid battery pack, keeping hard-to-recycle rechargeable battery components from entering the waste stream. The Hybrid Shop recommends hybrid battery conditioning every 60,000 to 80,000 miles, before the hybrid battery pack begins to impact fuel economy or performance, but how long does this last?

Toyota Prius’ nickel-metal hydride (NiMH) battery is very resilient, but it does have a limited lifespan in respect to its balance. The hybrid battery pack is composed of between 168 to 240 individual cells, assembled in 28 to 40 modules, depending on year, each of which ages differently. Over time, capacity and performance can vary greatly between modules, and a hybrid battery can only perform as well as its weakest module. Hybrid battery conditioning restores the whole pack to a well-balanced state, restoring as much as 95% of factory performance, and can last as long as the original new battery, delivering peak performance and fuel economy for an additional five to seven years.


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What other maintenance should HEV owners be aware of?

The HEV high voltage system is comprised of four major sub-systems.  These sub-systems are the Battery Pack, Electric Transmission (that contains a drive motor and generator unit – MGU), Power Inverter, and dc-dc Converter.  Some HEV systems also contain an Electric Air Conditioning Compressor.

Electrical Vehicle Diagram

Electric Transmission and/or Motor Generator Unit (MGU) Testing

During the life of an HEV, the 3-Phase MGU units (much like an engine system) age and eventually fail. From the time an MGU system is new until failure there is the “in-between stage” of stator winding and rotor aging. MGU aging or its other failure modes can cause the vehicle to surge, shudder, or intermittently cause a driveability symptom similar to an engine misfire. MGU’s can also exhibit audible noises, or cause the power inverter system to run at elevated temperatures. The MGU SOH should be tested at regularly scheduled maintenance intervals to trend/track its condition (aging), or test it if the vehicle has a customer driveability concern/complaint. It is extremely important to test the MGU system for SOH because, the electric drive motor is responsible for launching and propelling the vehicle during the first 20 – 30 mph of an acceleration, and the generator is responsible for providing the electric drive motor and battery pack electrical energy during normal vehicle operation. Most MGU performance problems will not cause the MIL to illuminate to inform the operator that there is a problem. Typically, the MIL will only be triggered when there are more catastrophic (chronic) problems. The MIL will typically not be triggered for intermittent MGU malfunctions.

Power Inverter and Control System Testing

To power the MGU system, the 3-Phase Power Inverter system receives direct current (DC) electrical energy from the Battery Pack system and inverts (changes) the DC energy to alternating current (AC) 3-Phase electrical energy. It then transfers the 3-Phase electrical energy to the MGU system to electrically propel the vehicle, operate with the vehicle engine to blend motive power to the wheels, and recharge the Battery Pack. When the Power Inverter and Control System are operating properly it provides smooth electrical energy to the MGU to electrically propel and move the vehicle. However, when the Power Inverter system malfunctions (either because of abnormal external inputs to its control systems or internal electronic malfunctions) it can cause the vehicle to perform poorly resulting in a sub-standard driveability experience for the vehicle operator. Therefore, testing the Power Inverter system SOH should be tested at regularly scheduled maintenance intervals to trend/track its operating condition or test it if the vehicle has a customer driveability concern/complaint. Most Power Inverter performance problems will not cause the MIL to illuminate to inform the operator that there is a problem. Typically, the MIL will only be triggered when there are more catastrophic (chronic) problems. The MIL will typically not be triggered for intermittent Power Inverter malfunctions.

dc-dc Converter System Testing

HEVs do not contain a traditional belt-driven “alternator” as part of the electrical system. The alternator (generator) provides electrical power to operate vehicle lighting, door locks, power windows, engine electrical systems, etc. The dc-dc Converter replaces the alternator to provide electrical power for operating all of the vehicle electrical systems. The dc-dc Converter is a solid state electrical system receives its electrical energy from the high voltage battery pack and converts (reduces) this high voltage to low voltage so that the vehicle can use this electrical energy to power the low voltage vehicle systems. The dc-dc Converter should be tested at a regularly scheduled maintenance interval for proper electrical power output capability and to ensure that its output energy is “quiet” (i.e., poorly filtered high frequency signals are not causing noises in the radio or other audible noises). The dc-dc Converter should be checked if proper 12 volt vehicle battery charging cannot be maintained, if the vehicle lighting is lacking brightness (lights are dim), or if blower motor speeds seem to be operating slower, etc. Proper dc-dc Converter operation is critical to the operation of all vehicle electrical systems, including the HEV system.

Other Maintenance Items

If the Power Electronics cooling system for the Power Inverter, dc-dc Converter, and/or Electric Transmission is a liquid system (i.e., a system much like the engine cooling system) ensure that it is maintained to prevent the power electronics from overheating. Maintain proper tire inflation in the tires. Many HEVs use “low rolling resistance” tires to enhance fuel economy and proper tire inflation pressure is critical to maintain high fuel economy. Have your service center check the orange-colored high voltage cables that are routed under the vehicle (exposed to road debris) for any cuts, tears, punctures, etc., permitting water intrusion into the cable. Water intrusion can cause various abnormal electrical operating conditions, including the vehicle not cranking/starting. Road debris not only can also cut through the outer sheath of the high voltage cable but, it can also cut through the cable shield and into the copper core. This can cause abnormal vehicle operation but, it can result in safety concerns. The service center technician can easily repair the cable. The cool/cold air from the vehicle air conditioning (A/C) system, on many vehicles, is used to cool the high voltage battery pack. If the A/C system is not performing or not operational it can cause the battery pack to operate at elevated temperatures. If the battery pack operates at elevated temperatures, the hybrid controller can command the system to operate in a “reduced performance” mode (i.e., vehicle has sluggish performance) to reduce demand on the battery pack so it operates at a cooler temperature

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What are the Pros and Cons of Hybrid Battery Replacement and Conditioning?

There are numerous Pros and Cons when addressing the issue of battery pack replacement or Conditioning.  When considering installing a used battery pack, there is always an issue of not knowing the condition of the unit.  Therefore, there is significant risk in purchasing used products.   Rebuilt units are always a consideration because there is an expectation that the battery pack has been tested and is sold with a warranty.  However, the reputation of the rebuilder needs to be considered before utilizing a rebuilt unit.  There are numerous HEV battery pack rebuilders that are using processes, procedures, and methods that are not grounded in industry testing standards.  Additionally, many rebuilders do not provide battery data with the unit for the purposes of documenting its performance.  Rebuilt battery units are typically ½ the cost (and ½ the warranty period) of a new unit.  New units can provide excellent performance with a good warranty from a qualified manufacturer but, this always is coupled with significant cost.  Conditioning provides a solid solution for customer.  When performed by a trained professional, Conditioned battery packs can provide excellent performance with minimal risk for ongoing electric propulsion performance.  Conditioning is approximately one-half the cost of a rebuilt unit that is usually accompanied by a 1 year to 18 month warranty period.

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New vs. Conditioned Batteries: Which is better?

A New battery contains all new (or qualified as new) components including battery modules, relays, wiring, electronic controller, etc.  A Conditioned battery pack utilizes the existing battery components.

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How does Hybrid Battery Conditioning benefit the environment?

Conditioning battery packs provides an extremely positive impact to the environment.  By Conditioning an HEV battery pack in lieu of replacement, far fewer battery packs will be produced or placed into the salvage stream.  By reducing the number of battery packs in the salvage stream this will reduce the volume of metallic and non-metallic materials in the recycling and refuse streams.  Conditioning battery packs results in reusing existing resources and reducing the need for manufacturing additional battery pack materials.

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How long will Hybrid Battery Conditioning last?

Battery Pack Conditioning typically will last from 18 to 60 months before the battery pack may need additional conditioning or needing individual battery module replacements.  Much of the Conditioning longevity is dependent on the following:

  • Age of the battery pack
  • Geographic area in which it has operated –  ambient temperatures and/or elevations, or its driving cycle (i.e., does the vehicle remain unused for periods or is it used daily or, is it driven on highway or city/suburban driving cycle)
  • The battery pack been permitted to be operated in a deeply discharged state by its owner/operator, or it has been serviced incorrectly by an untrained technician
  • Amount of electrolyte leakage

When the Conditioning process is performed, the technician will determine the battery pack SOH, and then advise the customer of testing results.  NiMH technology is very resilient and, if not abused, extremely aged, or operated in extreme operational states, should be a good candidate for Conditioning and provide the customer with a lower cost service solution.

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Should I have my battery conditioned or replaced?

Conditioning – Most hybrid electric vehicles (HEV) utilize Nickel Metal Hydride (NiMH) battery technology and can lose much of its capacity over time.  Conditioning a battery pack means that no components are replaced.  After removal from the vehicle the battery pack is initially tested for Power and Energy to determine its current state-of-health (SOH).  After initial testing, the battery pack is “cycled” (using a controlled charging and discharging process) to increase the capacity of the modules.

The capacity of most NiMH battery modules can be increased to approximately 92-95% of a new battery module by cycling.  If any of the battery modules fail to provide proper Power or Energy, a simple replacement of the individual non-performing battery modules can be accomplished to increase the performance of the battery pack.  Most battery pack performance problems will not cause the Malfunction Indicator Lamp (MIL) to illuminate to inform the operator that there is a problem.  Typically, the MIL will only be triggered when there are more catastrophic (chronic) problems.  If most battery problems are caught before the MIL is triggered, it can usually be Conditioned back to good health.  The MIL will typically not be triggered for intermittent or mediocre battery pack operation/malfunctions.

Battery Pack Replacement – is also another battery pack service option to the customer, albeit more expensive than conditioning.  Replacement of the battery pack can be accomplished in three different levels of service.  The three levels of battery replacement are installing a used, rebuilt, or new battery pack.

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