Yes, I still make these and you can ask me to build you one, or send me your Impossible Lab, converted to a Polaroid Back or not, for a battery replacement.
But for those of you far away, or handy with a soldering iron, or both, here’s how I build the replacement packs.
For the record:
I use two 3.7 LiPo cells , anywhere between 250 mah to 310 mah, cell model number is 502030. It just needs to be small enough so a sandwich of two cells fits inside the front of the lab.
For example: 3.7 310mah 503020 lipo cells on amazon
The size of each of the above cells is 1.22in×0.787in×0.2inch, 30mm x 19.8mm x 5.1mm.
The cells connect in series for a 7.4V battery and the resulting sandwich uses a JST-1.5mm 2 pin connector (you can cut and reuse the connector from the dead battery inside your Lab).
Keep the resulting total length of the wires to about 1” long, too long and they’ll bunch up too much and interfere with the rollers.
And watch the replacement video on the analogue.studio Rescue Me page when it comes to the replacement (well, before this if you want to reuse the wires from the old battery):
Good luck! And yes, you can and should use shrink tubes to insulate those soldered wires, I just forget every time.