I have two banks of 2 12 v batteries in series for 24v starting and house. Will this a 24v battery charger work for them?
Best recheck your system as very few systems are 24v. Most are 12 volt. 24v most times are for trolling motors. But not saying U don't if it's 24V and the charger is for 24V than it should work.
If you can find a 24v charger, you can charge a 2-battery 24V bank with it. You have a 24-volt starter motor, and 24 volt house accessories? Might want to recheck your terminology there.
If you have a 24V system then a 24V charger is appropriate. A twelve volt battery is a battery of 6, 2V cells connected in series, so connecting 12 2V cells together to make 24V is no different. 24 V systems are common in commercial boats, trucks etc. They function better over long cable runs as the amperage is halved for the same work at the higher voltage. If the charger sees a 24V load it will be happy, as will the batteries - it would be no good to connect it to a 12 V load as both the batteries and the charger will rapidly self destruct. Good luck.
