The older C-Type charger has been out of production for some time, and I'm happy to announce that the factory has come up with a new charger solution for the batteries.  These work with the NiMH celled batteries and will charge the ones with higher capacity cells all the way up.   I'm stocking the ones with power supplies with US plugs but have a few protoypes with Euro plugs so if you need one just e-mail me.

https://rolleiflex.us/products/rolleiflex-type-d-charger-for-6000-series-batteries-with-nimh-cells