DRAFT: TO BE REVISED AND UPDATED SHORTLY!! (RN)
Ni-Cads should be discharged before re-charging. The discharge rate can be any number of amps really, but ensure the battery stays cool, half an amp or less would be quite adequate. This can be achieved by placing a car bulb or some other lamp onto the battery. Once the light has gone out, the battery will be ready for charging.
To recharge a NiCad battery check what mA/h the cells are. if the cells are for example 500mA/h this would be divided by 10 to get 50mA and charged at this rate for 10 hours. This will ensure the battery has the correct amount of energy as it should have, however it is sometimes a good idea to give the battery an extra hour.
Fast charges are worked out the same way but so that you can work out the charge current for 1 hour. This means that what ever the mA/h rating the battery is, is the same current as for charging for 1 hour.
Fast charges deteriorate battery life and capacity, therefore they should not be done on a regular basis.
While these batteries are not in use it is best they are stored in their discharged state.