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Hybrid electric vehicles (HEVs or hybrids for short) have two types of batteries. One of these is the standard car battery that supplies the electricity required to start the internal combustion engine and support the alternator in powering various electrical systems.

The other is the hybrid battery. It powers the electric motor when the HEV operates in electric vehicle (EV) mode. A critical part of the electric drive, the hybrid car battery will undermine the HEV’s drivability if it develops an issue. Fortunately, there are symptoms of a bad hybrid battery that you can look out for.

Bad Hybrid Battery Symptoms

Like conventional car batteries, the hybrid battery wears out over time. Alternatively, it might develop issues unrelated to wear and tear. Whatever the reason behind its malfunction, a bad hybrid car battery usually displays warning signs that indicate it requires repair or replacement.

The most common bad hybrid battery symptoms are the following:

Illuminated Hybrid System Warning Light

HEVs have a warning indicator that lights up when the control module detects a problem with the hybrid battery. The hybrid system warning light varies in appearance between vehicles.

You can find the typical hybrid system warning light on the dashboard. It usually has an amber or yellow color. In some vehicle models, the light is a triangular shape with an exclamation mark within it. In others, the cluster display shows an appropriate message alongside the illuminated lamp.

While the hybrid system warning light indicates an issue with the battery, it can also illuminate because of a problem with a different part of the hybrid powertrain. The lamp will turn on if the electric motor, power inverter, control module, or another part fails. Still, a bad hybrid battery is the most likely culprit behind an illuminated warning light.

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Charging Problems

Like other chargeable batteries, the hybrid battery replenishes its depleted energy stores from an external power source. Heavy use can cause issues with the battery’s charging ability. A bad hybrid car battery might only accept lower current voltage, leading to a slower charging rate. In the worst case scenario, the energy storage device might not charge.

You can check the in-vehicle display for warning signs that the hybrid battery discharges too quickly or never shows that it reaches a 100% charged state.

The likely reasons behind a hybrid battery’s charging problems are bad battery cells, cell imbalance, and severe cell degradation.

Range Reduction

Not all bad hybrid batteries fail immediately. Some might continue to function, albeit at a reduced level of capability. These faulty batteries might retain enough capacity to power the electric motor in hybrid mode. However, their performance suffers, which can reduce the maximum range of your HEV in electric drive mode.

Bad batteries might store less power, charge more slowly, drain faster, or release less energy. They reduce your HEV’s endurance on an electric drive, forcing you to switch back to the gasoline or diesel engine sooner.

If the shorter range on electric mode wasn’t bad enough, the instrument cluster might show an inaccurate reading of the estimated distance to empty. You might get misled into thinking the depleted battery still has plenty of charge.

Bad Fuel Economy

While a pure electric car might become undrivable because of a faulty battery, your HEV might continue operating thanks to its hybrid powertrain. If the hybrid battery fails, the HEV can switch to its gasoline or diesel engine.

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However, an HEV with a bad hybrid drive battery will rely more on its internal combustion engine. This mode consumes fuel, so you will pull into gas stations more often and spend more on fuel costs.

Some HEVs also rely heavily on their hybrid battery. If the battery fails, they can stop working until they receive a replacement part.

Odd Noises

When something goes wrong with a part, it often makes strange noises. A bad hybrid car battery can also make odd sounds.

A bad hybrid battery might make a constant or intermittent humming noise. You might also hear clicks and pops from the battery’s general direction.

Many hybrid batteries have a cooling fan that regulates their temperature. If the energy storage device grows hot, the fan turns on and blows air over it to force heat away. Bad hybrid drive batteries tend to run hotter, so the cooling fan runs longer and more often. You might hear the noises made by the fan.

What Is a Hybrid Car Battery?

The hybrid battery is an energy storage device that powers the HEV’s electric drive and charging system. Most batteries have several modules arranged in series. Each battery module contains several individual cells that store energy.

There are several types of hybrid batteries: Lead-acid, nickel-metal hydride (NiMH), and lithium-ion (Li-ion). Each type has different costs, performance, and hybrid battery lifespan.

Lead-acid hybrid batteries use the same principles as the car battery in a gas or diesel vehicle. As the earliest type of hybrid battery, you can find them on the oldest HEV models.

NiMH hybrid batteries use metal alloys to store and release energy. Most hybrids use NiMH batteries thanks to their low cost and performance.

Finally, lithium-ion hybrid batteries use lithium as their primary material. They deliver the best performance but also have the highest price tag.

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Some HEVs use regenerative braking to charge their hybrid battery. Others rely on an inverter that pulls excess energy generated by the internal combustion engine. Plug-in HEVs can dock with EV chargers and charge their hybrid car battery like a pure electric car.

How Long Do Hybrid Batteries Last?

Many factors affect hybrid battery lifespan, but the most influential factor is the battery’s type. Lead-acid hybrid batteries usually last between 3-4 years before needing replacement. A typical NiMH hybrid battery has a lifespan of 8-10 years. Finally, most Li-ion hybrid batteries can last up to 12 years.

Keep in mind that heavy use can wear the hybrid battery out. The more you use it, the shorter the hybrid battery lifespan gets.

Repairing a Bad Hybrid Battery

Depending on the type and severity of the issue affecting the hybrid battery, you might need to either repair it or order a replacement.

Sometimes, you can restore the performance of a bad hybrid battery with battery pack balancing. Battery balancing redistributes the charge among the battery cells, ensuring each cell gets more or less the same state of charge.

Other bad hybrid batteries require reconditioning, a process where the battery modules undergo charging, discharging, and balancing. Reconditioning can extend the old battery’s lifespan by months or years.

How Much Does a Hybrid Battery Replacement Part Cost?

While it’s possible to repair some faulty hybrid batteries, others require replacement. A new hybrid car battery can set you back anywhere between $1,380 and $4,770. Before sealing the deal, ensure the replacement hybrid battery is compatible with your vehicle.

About The Author
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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