Full tends to vary according to the charger, but a safe full reading is from 1.45 to 1.5 volts per cell. The danger level is 1.55 volts
Empty as far as usefulness is concerned is about 1.2 volts per cell, their nominal voltage
They can be taken down to about 1.05 volts per cell, but at below 1 volt damage can occur.
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