Five NiCds implies what charging voltage?

[Duane Hess]

NiCADs are typically referenced as 1.2V, hence 6V for 5 in series. Other references are 1.25V. However, f1.2V seems way more common.

Can't help you with how much over 6V should be used for charging.

If possibe, charge them outside the device. I have 40yr old NiCADs that seem to work fine (very few). Most won't hold a chare, discharge quickly, etc. If NiCADs get warm while charging STOP. Unlike other batteries, they typically cool slightly when charging.

A word of warning, it might be well worth installing new NiCADs. I do not charge old BATTs long enough to be "full" even if apparently working 100%. Have forgotten to quit early and they do explode. Won't level the house but will break the frame of what they are in, which is typically plastic. (but even a single AA will sound like a loud pistol)

From the description, it sounds like there is no internal circuity. Might consider fabricating a removable battery pack utilizing a more modern battery technology. Lithium or NiMH; just have a config close to 6V. If the only device being powered is a pump motor, undoubtedly a variance of +/- 1V would EASILY be tollerated.

Batteries which have a button on top indicate the + end. Batteries that are smooth on both ends will have a "crimp ring" just below one end. I believe that is also the + end, but don't really know. Sometimes closely examining the charger port plug/recepticle will show +/-.