Besides the motor, does the hybrid motor power anything else? I tried stopping at a light with my fan on maximum. Auto-stop came on but the battery did not drain. But, I could have sworn I saw the battery go down at auto-stop before. And the one time my battery drained completely, my hybrid battery drained too.

 

The hybrid battery will try to keep the 12v up to normal like an alternator does. Basicly if the 12V drops enough the battery will provide 13.7 or so volts for a while to charge it back up.