What Happens if the Battery Dies on a Hybrid?

I came across something online that says if the hybrid battery dies, the car won’t drive anymore, even if it still has petrol. Is this true? I’m curious about how hybrids handle battery failure.

The main hybrid battery is protected, so complete failure is rare. You’ll get plenty of warnings before anything major happens. If the 12V battery goes flat, you can still jump-start the car.

Ashby said:
The main hybrid battery is protected, so complete failure is rare. You’ll get plenty of warnings before anything major happens. If the 12V battery goes flat, you can still jump-start the car.

Good to know, thanks. That clears up a lot of my worries!

Yes, if the hybrid battery dies completely, the car won’t start. Toyota hybrids use the traction battery to manage the entire system, so no battery means no driving. You can’t rely on petrol alone.

Keenan said:
Yes, if the hybrid battery dies completely, the car won’t start. Toyota hybrids use the traction battery to manage the entire system, so no battery means no driving. You can’t rely on petrol alone.

That’s right. Symptoms of a failing battery include sluggish acceleration, quick charge/discharge cycles, and the engine running more often when idle.

In my experience, a failing hybrid battery doesn’t leave you stranded immediately. I drove my Prius for a month with a dying battery until I got it replaced. Just watch for warning lights and reduced performance.

@Parrish
Thanks for sharing! Sounds like there’s at least some time to address the issue before the car becomes undriveable.

You can’t drive a hybrid without petrol either. Even with a fully charged battery, the system relies on petrol for extended driving. Mild hybrids especially can’t run on electricity alone for long.

CorollaCrew3 said:
You can’t drive a hybrid without petrol either. Even with a fully charged battery, the system relies on petrol for extended driving. Mild hybrids especially can’t run on electricity alone for long.

I had an empty fuel tank once and managed to drive a short distance on EV mode to a gas station. Definitely not something I’d recommend doing again!

For hybrid batteries to last, regular maintenance is key. Cleaning the cooling fan filter is a must. Batteries in the UK often last 15 years or more if properly cared for.

Wyatt said:
For hybrid batteries to last, regular maintenance is key. Cleaning the cooling fan filter is a must. Batteries in the UK often last 15 years or more if properly cared for.

Thanks for the tip! I’ll make sure to keep an eye on the cooling fan filter.