I am not sure where else to ask but there are a lot of smart people here.
I have a tiny remote control Helicopter which charges via USB or with a cable from the remote control handset (which of course drains the AA batteries in the controller). I am looking for the cable to charge it from USB but can’t seem to find anything other than a source in China that has a minimum order of 20,000 units.
The connector looks proprietary (or at least pretty obscure) to me. I would get another handset cable, lop the end off, and splice it to a USB cable. Make sure that there isn’t any voltage/current regulation going on - USB supplies 5v at up to 500mA, and you want to make sure that the helicopter can take a 5v regulated input.
I just saw in a store a couple of weeks ago, a AA charger that plugs into a USB port. Get one of those, and a set of rechargeable AA batteries, and keep swapping them. Assuming you can’t find the right cable for cheaper than that, of course.