Nominal battery voltage is 12V; for Pb acid cells, max voltage fully charged is 14.4V- you should never charge beyond this voltage (we use that as the cutoff value).
Fully down voltage is 10.8V; if discharged below this value, the battery will be damaged irreversibly. You should never allow the voltage to fall below 11.4V.
Under regular use, the battery should not be allowed to go beyond 12-13.2V (you should see this voltage with a meter during normal use.
All batteries has some leakage current- self-discharge- which is always talking place (including charging and discharging periods). The leakage depends on the total battery capacity and construction (and perhaps age).
For 7.2AH capacity, I would guess (hazard!) a leakage current of about 10-20mA. Some batteryman say that leakage is less under a nominal load (say 50mA for a battery of 7AH capacity). So your charging current should be more than 20mA (unless the voltage goes above 14V). Plus you add the loss during normal working (load discharge).
If you charge at constant voltage of 13.8V, the current will be around 100mA (will decrease slowly to 10-20mA over time) if the battery is partly discharged. You should limit current to 100mA (approx) and the voltage to 13.8V. Battery chemistry will take care of the rest. If it is a sealed maintenance free battery (most 7AH capacity batteries are gel type) you should not allow 400mA under normal charging.