For quite a while I’ve had a smarthings Multi sensor lying around that I’d snapped one of the battery contacts off. In an attempt to make it useful again I’ve shoved a LiPo cell and usb charger in there. It takes significant modification of the housing to get it to fit, and I think with a bit more work I can actually get it all in there and closed properly. I had to flip the main board over and drill holes for what I’m assuming is the temperature probe and what I know is the reset button. Sorry about the state of this, I couldn’t get all the sticky pad residue off…
Red charging light - turns green when charged:
This is the charging unit I used:
Red arrow shows positive terminal on the board, black arrow shows negative terminal… or where it should be anyway. Whatever you do, if you’re trying this, do not rip the copper pad off the board, if you do you’ll have to find somewhere to scratch a bit of the protective film off and solder a wire to a tiny little point without shorting anything.
And this shows how it all sits in the housing.
Now that I know the concept works I’ll either design an new housing for 3d-printing, or modify this one some more so it fits together properly. I only need to find another 1mm and I think i can do that by cutting bits out of the lid. I’ll report on battery life in a couple of years when it runs out.