Car died over night…

Vercingetorix

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I'm wondering if there is a software issue which causes one the relays, which isolates the 12v battery, to be triggered and disconnects a good working 12v battery from the car. Speculation on my part.
I’m 99% sure there is nothing in the car which isolates the battery. Lithium batteries get destroyed when they are fully drained. As such most Lithium batteries have a built in cut off which cuts themselves off when the voltage gets below a certain level. It makes them easy to jump because they really aren’t dead. All that needs to happen is enough charge is put into the battery and then the battery turns itself on, and the car with it. Many smart chargers that handle lithium batteries are equipped to give the batteries a jolt to turn them on and allow them to charge. This also is speculation.
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Windpower

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I’m 99% sure there is nothing in the car which isolates the battery.
Someone had previously posted a block diagram of the high voltage and 12v charging and powering circuits. I seem to remember there were relays isolating the 12v battery. If so, I can imagine a case where the relay triggers even though the battery was fine.

But this is pure speculation on my part. Its possible that both things happen: the 12v gets somewhat drained and then the relay isolates the low voltage battery. And then the car is dead. If so, the question is what is happening to cause the low voltage battery to drain.
 
 




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