C350e worry

[tode]

And so if the HV battery is depleted (ot faulty), then the 12V battery doesn't get charged, and you can't start the petrol (or, in your case, Diesel) engine, thus living the car immobilised? If so, then this seems to defeat the purpose of having a hybrid in the first place..

In any event, for the ICE engine to charge the HV battery, there has to be a device that converts circular momentum to electricity (alternator...) somewhere?

I'm on a pretty steep learning curve with this car, but AFAIK the petrol engine can only be started with the electric motor (since there is no starter. So, yes, if if your HV battery is empty (which it shouldn't be ) you can't start the car at all.
On the other hand, if the HV battery is low, then you can run in "B" mode with the petrol engine and the HV battery gets topped up, but very slowly (the electric motor being used as an alternator) . . .

I've hunted all over the internet for a detailed explanation of how exactly the car manages the balance between the two batteries and have found . . . nothing