Nicad batteries are excellent for situations that require high current delivery for a short time. IE Starting a jet engine, thay also maintain there nominal voltage for a longer time, followed by a sharp drop off.. Lead acid bateries delever a lower current for a longer time, but votage starts to drop off quickly.
Servicing of an A/C L/A battery usualy involves charging at a fixed current for a certain period of time or until the specific gravity of the cells reaches 1260. Usualy the tested for capacity, and recharged.
Nicads can either be charged at a constant current, at a combination of constant current/constatnt voltage or reflex charging.
Reflex charging involves charging at a high current (1 Hr rate) with pulses of discharge. This process helps charge with reduced heat generated, and helps minimise the memory effect..
Constnt Voltage /Current involves setting the charge voltage at about 1.4 volts per cell, and then setting the charge current. The current will be maintained until chg voltage is neared, and the current grops off.
Constant current is exactly that, a current is set (usualy at the C4 rate : ) and continues for 150 % of the battery capacity.
Deep cycling of a nicad involves totaly dicharging until the individual cells are at zero. As the cells reach 0 they are shorted out to prevent charging in reverse as this will destroy the cell. The battery is usualy left for at least 16 Hrs with the shorting strips on to stabilise the cells. Recharging and cap testing follows.
These basically the methods I have used over the last 30+ years on Mil A/C batteries. Procedures have changed a bit with the introduction of newer batteries and chargers.