The nominal voltage of the Ni-Cd type battery is 1.2V, which is used to build your system.
In 10 NiCd cells configuration, 12V will be nominal voltage.
But normal working conditions are not the same because it is usually working on the float charge of 1.40V per cell (It depends on the type of Ni-Cd battery but most commonly 1.40V ~ 1.42V) and boost charge 1.45V per cell.
The main concern when charging batteries is the current limitation. You should set it to max 20% of your Ah value e.g. if your battery is 100Ah set it to max 20A(if possible, please refer to your battery datasheet). Another point monitoring battery temperatures. In some cases (mostly in industrial or any other critical projects) battery temperature compensation feature requested with charger equipment due to set current limitation lower.
P.S: I don't know your batteries are sealed (maintenance-free) or not. If not, you should check the electrolyte level too. Usually, there are marks on the case.