I'm assuming your wall charger is a lipo charger. Did you give it a full charge with the wall charger before trying it in the car?

Which cable do you usually connect when charging your batteries normally on the imax?
You should be charging through the main battery plug, and if you are balance charging then you connect both the main plug and the balance plug.

Also, does your esc have a lvc?
If you drain the voltage on your lipos too low they can be permanently damaged.