Depends on the battery
, and it's chemistry, as in AGM
, flooded, Life-Po?
Best idea is to find the manual for the battery brand and type you have and follow it.
Normally a charger
is three stage, Bulk where all the power you can make is tossed into the battery until the bank hits the absorption voltage, where voltage is held constant until the amps drop to a low level, then it shifts to float which is a lower voltage level.
Most, all? Stock alternators are just constant voltage between 13.8 and 14, like an automobile and this is terrible for charging
a deep cycle bank.