It’s a tiny battery charger for spare Crazyflie batteries!
This little gem is a 500mA charger based on the MCP73832 single-cell LiPo charge controller. It’s exceptionally small and works with the stock Crazyflie 2 batteries.
One of the cool added features are the connection points you can use to solder multiple chargers together in a chain, thereby creating a charging station for multiple batteries. For the sport flier, I can see this as being a great way to increase flight times or make multiple-battery racing heats. For the researcher, these will go a long way to increasing precious flight time for further data acquisition and experimentation.
Seeed Studio is stocking these with extra batteries for $8 USD (a battery alone is $5.50 USD) so the price is not restrictive if you want a few of them!
I picked one up the other day and found it quite useful. I have a few Crazyflie 2s and these days I love using my Devo 7e so much, I’ve set the channel and data rate the same on each of my ‘flies to facilitate control with the Devo 7e. Of course, if I plug a Crazyflie in to charge it, I can’t fly another since the transmitter controls both the one I’m using and the one I’m charging! I accidentally realized this the hard way. Now, I disconnect the battery of the one I’m charging so that the Crazyflie doesn’t have to be “on,” and I can charge the battery with this little charger while I fly my other ‘flie. As a result, I can keep the channels the same on all my ‘flies and not have any unintended, tethered flights!
I might have to pick up a few more chargers and put together a charging bank!