Back when I had a Rollei I would rebuild the cells using NiMH cells which last a lot longer than the NiCads. I had a Maha charger, I think there was a 777 in the model number. The Maha charger worked great for the Rollei batteries since there were adjustable prongs. All you have to do is line up the prongs, and slide the battery on to them. The charger was great for all kinds of other batteries too, and wasn't too expensive IIRC. I highly recommend you go this route.