How does generator charging work?

The charge from a generator will first be limited by the generator’s ability to provide power and later by the power system’s (batteries’) ability to receive power. The aim is for the first phase to be as long as possible.

A healthy and correctly connected generator should be able to raise the voltage of discharged batteries to just over 13 V. Then it should stay
there for the entire time that the batteries are receiving a lot of current.

If the charge reception is good, as in the graph, the generator will take at least an hour before it rises above 14 V. This assumes
good batteries and a low voltage drop, i.e. good cables and connectors.

If, in a similar situation the next season, the voltage rises above 14 V after half an hour, it is time to change the batteries.