When I recently started looking for parts to make more of those robots, I had an unpleasant surprise: the battery protection chip that I used, HT3062E, can no longer be easily bought. That is a big problem, so I went to look for another chip instead. Unfortunately, there don't seem to be very many integrated solutions out there – most chips require separate mosfets, which is something I would rather like to avoid. So this time I went for the DW07D, which is for a bit lower current, but should still work. Unfortunately it comes in a different package and requires different connections, so a new PCB design is required.

I also added a mosfet for the speaker, and some handles at the top of the PCB, to make it easier to attach things to the robot.