[Closed] Nicads and chargers and runtimes

Hi I am building a nicad set to run my helmet light.
I have the cells. I would like to build a 13.2volt system.
However the slow charger I have was used for a 12volt nicad system. Not sure of the actual voltage coming out of the charger.

Do you think it would be ok to use this charger for a 13.2 pack?

I suspect the old charger is giving about 13ish volts out in which case I suspect not. If this is the case then I will just run it as a 12volt system.

Also how can I calculate the run time if I am aware of the bulb I am using (12w) and the cell capacity 1500mah?

Cheers