Attached you can find a STL file (under Media) to 3D-PRINT a charging tray for the new pin layout (remember blocking some pins so the Rollei Charger N cannot fry your new battery). The 3D Model can also be downloaded from here: https://www.thingiverse.com/thing:215677...

Print the 3D Model (or get it printed online).

Get a connector socket (for the charger I used I got one of these: https://bit.ly/2NwmhUo ) with 12.6mm diameter (you can use others but the 3D model might not fit then).

Solder wires to two pins (check the diameter of the pins so they fit the battery!) Make sure they're tick enough to have electrical contact. I used two small nails I shortened. Glue the pins into the two holes so they stick out roughly 5-6mm. Validate that the battery fits and connects (use a meter!)

Solder the other ends of the cables to the socket and glue the socket into the hole. Fill the bottom side of the tray with hot glue to fix everything.

A charger can be ordered from eBay: search for 11V Charger 1A Smart to 9.6V LiFe LiFePO4

https://www.ebay.com/itm/11V-Charger-1A-...