Charging 12V Batteries with a Generator
Some generators may have a 12-volt output on them, but they are not designed to charge your batteries directly. There are two main reasons why:
First, the chances are your generator’s DC outlet is limited to a current of about 8 amps maximum. So any battery will take a while to fully charge.
Secondly, the voltage of the DC output isn’t regulated – it varies according to the generator’s RPM. This is fine if the generator is running a low load, but not if it’s running a medium to high load. Also, the generator won’t cut back the charge when the battery is nearly full, so you can’t risk leaving it charging for too long.
Charging your batteries from your generator is only suitable for emergency or short term charging, anything more is a potential risk to your batteries.
What’s the Solution?
The best way to charge your battery is to run a proper 240-volt battery charger off the generator’s AC output. This will recharge the battery much faster and accurately. Also, most chargers regulate themselves down, so as charge builds in the battery, the charger won’t be pushing the same amount of amps.
So as a backup or alternative to your solar set up to charge your battery system, portable inverter generators are a great option, especially as you can also run your appliances on 240V straight from the generator also. But just remember, when charging your battery system off a generator, use a quality battery charger plugged into your 240V outlets instead of the generator’s DC outlets.