You don't have to ever turn your battery banks off to recharge the batteries in them with a Generator Bank. Shoot, due to a bug, it is possible to power up to 300W worth of stuff with dead batteries in a battery bank, by using another battery bank with at least 1 unit of power left in at least one battery, and a switch between them. The batteries in the bank that have a charge will never drain. I believe the bug is triggered by a server restart. If the bug ever stops working, a simple toggling of the switch between battery banks will trigger the bug again. Discovered this in A16.4, not sure if it was present in earlier versions of A16.It will charge the batteries but you must turn the generator on first then turn the battery bank on or they will not charge.
If you're running on batteries and notice they're getting low, you must turn them off then turn on the generators then turn the batteries on
Once you have a generator you really don't need to do this I just wondered if it would work