Question, I can't recall right now, but are the latest builds of DI recargeable in any sense?
Nope the will use button batteries, but early testing on ver 14 boards showed over 1000 injections
Unfortunately, while rechargeability was tested, I couldn't find a suitable power source. Supercapacitors at this size just can't deliver the current required (10mA) and there are no rechargeable batteries that could fit. Not to mention, even if there this was, say, a LiPo or Li-ion that would fit, it would introduce significant extra cost and shipping issues. I imagine it would also be subject to some strict regulations.
On the previous revision of the DragonInjector, I used a standard CR1216 button cell. During testing we got around 1300 injections, if I recall right. The CR1612 that the final revision uses actually has a much higher power density versus the CR1216, and can deliver more current without affecting its capacity rating.
Testing will happen soon, but I'm expecting around 2000 injections on a single battery. Shelf life of these batteries is about 5 years before they start to lose capacity, and the DI shuts off if it's not plugged into anything, so even if you inject a payload twice a day your DI should last 2 years before requiring a new battery. When that happens, the battery is easily replaceable by removing four screws. A tiny Philips screwdriver to do this is supplied with every DragonInjector.
One last thing to consider - with a rechargeable battery, at this size it would be a requirement to solder it to the board, making replacement when it inevitably couldn't hold a capacity anymore an issue. With a button cell, the DI will work as long as they keep making CR1612s. So, in 20 years when you dig your Switch out of the closet, one coin cell later your DI will be good as new.