I am a little confused about which battery does what.

[John77]

Hi I have a PHEV. I have read on here that things like using the heater AC effect the range on electric. So what is the small, normal battery for? On a normal petrol car the battery starts the car and everything else, but from what I have read on here the High voltage battery does all this. To me this seems stupid. Why is this when you have you have a perfectly good auxiliary battery? Plus if your HV battery went tits up then you could still start the car and still use it, which apparently you can't if the HV Battery dies. Maybe I am missing something or being too sensible.

 

[malcolm E53 AMG]

The high voltage Lithium-ion battery which typically operates at 350-450V runs an electric motor for propulsion, air conditioning compressor, coolant pump and starter/alternator.

The 12V battery controls the engine ignition, ECUs, wipers, door mirrors, ICE and Nav and other functions.

The 12V/350V circuits share an alternator/invertor to keep both systems charged.

If the 12V battery malfunctions the car won’t function even if the 350V battery is healthy as it controls start-up and main functions.

 

[John77]

The high voltage Lithium-ion battery which typically operates at 350-450V runs an electric motor for propulsion, air conditioning compressor, coolant pump and starter/alternator.

The 12V battery controls the engine ignition, ECUs, wipers, door mirrors, ICE and Nav and other functions.

The 12V/350V circuits share an alternator/invertor to keep both systems charged.

If the 12V battery malfunctions the car won’t function even if the 350V battery is healthy as it controls start-up and main functions.

Thank you, but why not have the 12v battery starting the car, then when the high voltage battery fails, you could still use the car in petrol. Crazy system.