Ni-Cd battery voltage indication of 100% charge
The nominal voltage of the Ni-Cd type battery is 1.2V, which is used to build your system.
For example, if you have a 110V DC system you calculate the number of cells you required using the nominal voltage which is (110 / 1.2) 92 cells.
But normal working conditions are not the same because it is usually working on the float charge of 1.40V (It depends on the type of Ni-Cd battery but most commonly 1.40V ~ 1.42V) and boost charge 1.45V.
If your batteries are not brand new so in this case voltage can be delusive about your fullness of batteries. Even in stored brand new batteries, there will be some capacity loss after not charging them for 6 months.
The correct way to understand is your batteries are full or not is by watching the drawn current.
So the way to understand your batteries are full or not you should connect them to the charger and set it to boost level 1.45V (please refer to your battery datasheet and use that value if that is different and also be sure that your charger has a current limitation and set it to 20% of your Ah value e.g. if your battery is 100Ah set it to max 20A) and watch the drained current. If it comes near to zero then your batteries are full.
After batteries are full you need to disconnect from the charger and when you measure battery voltage it will show you the full capacity voltage of your battery.