And no, you can’t roll start them.
I imagine you “can”, it’s just not very effective. Like, if they allowed you to switch it to regenerative breaking and let it roll down a hill. The problem is you can’t get out any more energy than you put in. So if the battery is dead and you roll down the hill you won’t be able to rull any farther up the other side than you started (even less when you factor in mechanical -> electrical -> mechanical. You’d probably better off putting it in neutral [if that’s a thing for electric cars] and just let it roll)
No, you actually can’t.
For safety reasons, the 400V main battery isn’t hardwired to the car. There’s a couple of contactors powered by the 12V battery that connect it to the car.
If your 12V battery dies, the contactors open and the car is completely dead. You have to jump it or replace the 12V battery, then the contactors pull in, then the main battery can start charging the 12V.
Even plugging it in doesn’t work - the car won’t take a charge if the electronics are dead.
If the main battery is dead but the 12V hasn’t died yet, you can try regenning down a hill or plugging in or whatever. But if you lose the 12V, the car’s bricked.
It’s set up that way so that first responders can get to an accident, pop the hood, cut the 12V and then start cutting you out of the wreckage without worrying about high voltage cables.
Yeah, obviously there’s technical reasons why. I was just approaching the problem theoretically. And then showing why the theory is stupid. It makes sense that they would implement other things for safety, especially if avoiding them only enabled a completely useless solution to a dead battery.
