Flooded NiCd is charged with a constant current to about 1.55V/cell. The current is then reduced to 0.1C and the charge continues until 1.55V/cell is reached again. At this point, a trickle charge is applied and the voltage is allowed to float freely. Higher charge voltages are possible but this generates excess gas and causes rapid water depletion. NDV is not applicable as the flooded NiCd does not absorb gases because it is not under pressure.

https://batteryuniversity.com/learn/article/charging_nickel_based_batteries

https://www.aviationpros.com/engines-components/article/10387569/nickelcadmium-batteries-basic-theory-and-maintenance-procedures

https://www.youtube.com/watch?v=UZM3aHANScc

https://www.led-expert.sk/index.php?main_page=product_info&products_id=2236