That's it. Runs in parallel with the bec. bec keeps the batt at the same voltage as the bec output. Never worry about charging it, I use 7.9V and its 250mah. You do have to turn the switch on and off and I try to get the batt to the same voltage prior to hooking it up. ie, I don't attach a fully charged 8.4V batt to the system, its at 7.8 or 7.9V prior to hookup.

Never heard of a spinning motor powering up an esc's bec, that's a new one.