Quote Originally Posted by dragons_fire View Post
i might remake the body so that its big enough to fit an alkaline 9V (its fibreglass and only took about 10 minutes to make). if i go to an alkaline, i cant charge it from a base station though, and nicads or nimh dont have much capacity.. alkalines are just ofver 500mAh at 9V, and the nicads are about 150-200 at 7.2V and nimh are about 300mAh at 7.2V....
You've got the base set up so you can stack PCB's on top of it. Make a board that'll hold a pack of AAA NiMH batteries laid flat and sits on top of your other PCB. They go up to about 700mAh in the AAA types. As far as shutting down at 2.5v/cell on the Li-Poly packs. Easy to set up an ADC pin to handle that for you. Kill the motor drive once you hit about 2.8-2.9v/cell, and that gives you plenty of time to put the thing on a charger. Have it beep or something to let you know.
I most definetly wouldn't go with alkaline batteries. It'll end up like a kids toy...run it for 5 minutes, then change batteries...