What Happens If Your Hybrid Battery Dies?

In hybrid vehicles, a high-voltage battery serves as the primary power source for the electric motor. These components and the electronics that govern them work with the car's internal combustion engine (ICE) to provide instant torque and save fuel.This system also allows drivers of hybrid cars to enjoy quiet, emissions-free moments at lower speeds. As you might expect, the high-voltage batteries used to power these motors are quite hearty. In fact, most hybrid batteries can last 10 to 15 years depending on driving conditions and charging habits, but all hybrid car batteries lose capacity over time and will eventually need to be replaced. This can be quite expensive; Toyota Prius owners can save money by swapping their own batteries, although this can be a risky DIY job.

Changing an internal combustion-powered car battery is a simpler matter, and a dead ICE battery can usually be remedied with a quick jump start. If the high-voltage battery in a hybrid vehicle calls it quits, you'll probably need more than a quick boost from a friendly passer-by or your handy portable battery pack. After all, high-voltage hybrid car batteries are essential to the motor's operation. So, when the battery dies, the car will likely perform poorly and less efficiently, and might not even run at all.

A dead battery can be an unforgiving showstopper for many traditional hybrids that rely on a gas engine and electric motor designed to work together. If the battery that powers the electric motor fails, some cars revert to a limp mode, placing all of the workload on the gas engine. While your car might still run smoothly up to highway speeds, you'll miss everything that makes a hybrid worth driving: the quiet starts, regenerative braking, and tremendous fuel savings. You'll also put more wear and tear on the gas engine and transmission with each mile driven, possibly leading to higher maintenance and repair costs.

Of course, not all hybrid vehicles respond the same way when the high-voltage battery dies completely. Some cars rely on the hybrid system's battery to power other functions, so check your owner's manual for specific warnings about your vehicle. Even if your car starts and runs with a dead high-voltage battery, you should avoid driving it for too long. Although replacing the high-voltage battery can be an expensive repair (a new hybrid battery for a Honda Accord costs around $4,000), it's best to address it quickly. Whether or not the expense makes sense for you depends on the value of your car and your plans for it, but you don't want to compromise your safety to save some money.