Thanks very much! I'll take a look. I'm interested in projects like that.There is a thread in the Focus section and I'm still working on the final version. It's just a 20 cell hoverboard battery that gets plugged into a Rosenberger cable/connector. The Focus Jam2 senses the battery when plugged in and uses it until it's unplugged or depleted. All the other work is about packaging. My latest will be a 3.6" diameter "bottle" in an oversize waterbottle cage with a charge level meter. Waiting on a friend to make the final version of the bottle. The hoverboard batteries are inexpensive but the one I've settled on uses 3500mah Sanyo/Panasonic cells and cost a bit more than the cheap Chinese batteries. It's also just a bit slimmer so I can keep the already large bottle size down to a minimum. The one I'm currently using was built in the US and cost $129. I think there are similar ones on aliexpress for around $31. I just don't know if these are very good but this one look to be a very compact build size. US $23.68 36% OFF|36V 7ah 6Ah 4.4Ah 5.2Ah high drain 2 wheel electric scooter self balancing lithium battery pack for Self balancing Fits 6.5