If you are talking about a 12 volt battery, then the float voltage is 13.8
volts and the current required to overcome the losses would be 12 ma.

You can use a constant 13.8 volts to charge it and then keep it charged,
however you should limit the initial charge rate to 1/10 of the total
capacity - which would be 1.2 amps.

You said 14 volt battery in your post, and the float voltage would be 16.1
for that.

Colin