Festool made two different types of chargers for the CDD and I think TDD drills. One type was the more common "60 minute" "quick" type charger, that charged the batteries with 2 amps more or less of power. The other type of charger was an "Ultra Rapid" "15 minute" charger that charged the batteries with around 6 to 8 amps. Festool offered or supplied both charger types in Europe and maybe elsewhere, but in the USA and probably Canada, Festool only supplied the Ultra Rapid type charger.
From what I understand about battery cells, and the literature from various tool manufacturers, the Ultra Rapid chargers where actially better for quality NiCd cells and could extend the lifespan of the cells a few times over the lifespan of cells chargered with the lower amperage chargers. The chargers where also made to charge Nimh celled batteries, but Festool never sold those for the CDD or TDD drills in the USA. The extended life for the NiCD batteries have to do with crystals that build up in the battery cells. The ultra Rapid chargers apparently break these down. I'm not sure how long it would have taken the Ultra Rapid chargers to charge the BiMh cells since those were higher amp hour rated.
There seem to be a wide variety of NiMh cells available nowadays, and some types don't like high amperage Ultra Rapid charging. It's possible some replacement batteries are manufactured using cells meant for lower amperage slower chargers. It's also possible some replacement battery manufacturers are worried that the older chargers were simply not made to charge NIMh battery cells at all, since some older chargers from various manufacturers including Bosch were not.
The other option would be to find a battery recelling service and check what cells they use. My preference were the Sanyo/Panasonic japanese NiCd cells used in the older 2.4 amp hour Milwaukee tools.
