How to determine the state of charge of a NiCD battery when charged via a Bench PSU?
The &quot;fully charged&quot; voltage of NiCd cells is quite unpredictable so you cannot and should not rely on the voltage of the cells.

the C / 10 = 700 mA ( C = cell capacity, so 7000 mAh for the cell in the photos) is generally a safe current to charge a NiCd cell.

When a NiCd cell is full but you keep charging it, the cell gets warm. The C / 10 current is then usually a safe current as that means the cell will not get too warm.

If you want to fast charge, use a proper fast charger but since this is a non-standard cell size, such a charger might not exist.

Proper fast chargers fir NiCd cells monitor the voltage and the temperature of the cell. The voltage of NiCd cells drops by a very small amount just when it is fully charged. It is a property that can only be used when you monitor the very carefully, you need special equipment or a purpose designed circuit to use this safely.


Have you read this article at battery university?
When using a lab supply to charge such cells I usually set the supply to about 2 V per cell (you can charge several of same capacity in series) and set the current to C /10 or lower so that is takes a long time but this will safely charge cells that are still accepting a charge.
If a cell has a very low voltage, like 0 V, then sometimes you can bring it back to life by charging the cell with a large current of say 1 A for a short time, like one minute. If the cells after that still doesn't show a voltage of more than 0.5 V, it really is dead. Treat such cells as chemical waste as Cadmium is very toxic to humans (and that's why NiCd cells are now replaced by NiMh cells).