What happens if the battery dies on a hybrid?

[FlyFishLarry]

Google tells me "If your hybrid car won't start because your hybrid Battery dies, you cannot drive the car anymore. You would have to replace the Battery in order to keep driving the vehicle, even if it's a hybrid and it still has gasoline."

is this correct?

[flash22]

The main pack is protected, so it can not happen, you will get many warnings before anything major happens

Toyota's hybrids do not have an alternator or traditional starter motor and the water pump, brakes and steering are all electric (some early JDM cars are different)

If the 12v Battery goes flat, you can manually open the car, pop the bonnet and jump the car

[FlyFishLarry]

14 minutes ago, flash22 said:

The main pack is protected, so it can not happen, you will get many warnings before anything major happens

Toyota's hybrids do not have an alternator or traditional starter motor and the water pump, brakes and steering are all electric (some early JDM cars are different)

If the 12v battery goes flat, you can manually open the car, pop the bonnet and jump the car

Thats good to know, thank you!

[fred88]

Yes, really interesting.

[TonyHSD]

1 hour ago, FlyFishLarry said:

Google tells me "If your hybrid car won't start because your hybrid battery dies, you cannot drive the car anymore. You would have to replace the battery in order to keep driving the vehicle, even if it's a hybrid and it still has gasoline."

is this correct?

Yes that is correct.
If your hybrid Battery dies you can not drive the car anymore.  
The traction Battery power is used by the car computer to electronically control the hybrid system work load and speeds. No power means no engine can start and run. Some people thing that when the traction Battery dies they can continue on petrol alone with reduced efficiency, this is not possible in Toyota hybrids. 

Most common signs for bad hybrid battery are: 

-reduced efficiency of the petrol engine,  slow accelerations and lack of power when pushed. Quick discharge, battery not able to hold charge long enough, more often engine running when stationary waiting at traffic lights etc. Quickly  full charge too when going downhill or engine running stationary to warm up itself and charge the battery. More often cycles charge and discharge. 
 

[Roy124]

I believe the converse is true too.  You can't drive without petrol, at least for the mild hybrid with the very small Battery.  I don't know about PHEV with a larger Battery.

[AisinW]

On 3/25/2023 at 4:26 PM, FlyFishLarry said:

Google tells me "If your hybrid car won't start because your hybrid battery dies, you cannot drive the car anymore. You would have to replace the battery in order to keep driving the vehicle, even if it's a hybrid and it still has gasoline."

is this correct?

Fortunately I can still go without being stranded when the hybrid Battery is failing on my 06 Prius in 2017. I was in Florida with hot summer and has no garage.  In UK, your Battery last at least 15 years as long as you clean the cooling fan filter regularly. It will give you triangle and christmast lights for several months / thousands miles.  I had mine died and I still can drive it for another month until I got replacement Battery. The main symptom is very check engine lights.  You only feel the  sluggish performance when the battery only can float at certain % because one of the module is weak or overheating.  You will also hear loud cooling fan on the back seat. 

[AisinW]

On 3/25/2023 at 6:06 PM, Roy124 said:

I believe the converse is true too.  You can't drive without petrol, at least for the mild hybrid with the very small battery.  I don't know about PHEV with a larger battery.

I also had once empty fuel tank.  The car gave christmas lights on the dashboard and go to limp mode and turned off.  Fortunately, accross the street was gas station and I  powered my car on, it was able to go to EV mode for few meters away.  I will not do that anymore, and I would rather push the car instead.  I was too stupid ignoring fuel lights too long.  I tought it was just on, but it turns out was on for few hundreed miles before.  Starting the car on empty tank will burn the fuel pump instantneously 

[FlyFishLarry]

12 hours ago, AisinW said:

Fortunately I can still go without being stranded when the hybrid battery is failing on my 06 Prius in 2017. I was in Florida with hot summer and has no garage.  In UK, your battery last at least 15 years as long as you clean the cooling fan filter regularly. It will give you triangle and christmast lights for several months / thousands miles.  I had mine died and I still can drive it for another month until I got replacement battery. The main symptom is very check engine lights.  You only feel the  sluggish performance when the battery only can float at certain % because one of the module is weak or overheating.  You will also hear loud cooling fan on the back seat. 

This is great info, thanks for sharing.