You have over charged the pack
If it is a NiCad pack, it should be OK.
That voltage, unloaded is OK.
Was the pack warm or hot prior to ending the charge?
ORIGINAL: ml3456-RCU
While cycling my 600 mah cell for the upcoming spring season, its voltage was 6.4 volts after 11 hours of charging. It was being charged at .83C after being discharged to 4.4 volts.
Is my battery still good? Is this too high for the battery? Using the Ultimate Charger that Dr. Suding used to make.
Thanks, Mark