I have 7 NiCd batteries hooked up in series (ordered from china) for a spare time project of rebuilding an old battery drill. Have been trickle charging them with 8.7V and 0.04A. When the battery is full it shows 8.6V The thing is when I hook it up to the drill the voltage rapidly in like 1-2 seconds goes from that to 8.0 also the amperage goes from 1A to 0.7A drawn from the batteries. Have been researching these kinds of batteries and it seems that rapid voltage drops are not their thing. Am I doing something wrong or is it possibly a problem with the batteries.
Technical specs: Drill is a Bosch 8.4V all I could find on the net. Batteries are NiCd stack of 7 each 1.2V and 600mAh.