What causes an ESC to fry if batts are left connected?

[BrianG]

Thanks for chiming in Patrick.

Now that I think about it, I think I have it happen to me too with a MMMv1. But since it was a V1 (and modified to remove the BEC because of the issues back then), I'm not sure what the actual cause was. All I know I was running around at the LHS. Someone came over to chat, so I just let it sit, and about 5 minutes later it started smoking. Batts were fine and still plenty charged.

Like I said, the only thing I can think of is if the ESC is drawing enough quiescent current that at higher voltages, the resulting power loss is too much for the heatsink and it just overheats until poof. But I think that's reaching.

I'd like to experiment with this a bit more, but don't have the disposable cash to replace ESCs if/when the fry.