Ask PYS: Power

House Battery Bank - Ken, on Feb 25, 2015 asked:

We purchased a new motorhome last summer and I was having some trouble with keeping the house batteries charged. I am not sure if the charger I have is the best one for the job. There are 4 US 2200 XC Batteries that are charged by a Magnum ME 2012 Inverter/Charger. There is a remote (like the one you put on our boat) but it does not have SOC info and I do not know why my batteries die so fast. What accessory do I need to install to have proper SOC readings? There are two systems (a 110V and a 24V), five televisions, water pump, fans, lights, residential fridge, and a few others that all seem to run off of the battery bank when not connected to shore power. If I’m a betting man the draw from the fridge alone will kill those batteries in a matter of a couple of hours. It has a built in Onan Generator that I use to charge the battery bank, but I have to run it all the time. I do not know if my batteries were damaged from misuse when on the dealerships lot.

The four golf cart batteries make for an OK at best battery bank. The Magnum ME 2012 charger has a 100 amp charging capacity and remote has the ability to become a battery monitor. It is called the battery monitor kit and retails for about $200. That way you will get a SOC for your batteries.

All of this load adds up to a huge amount of power but the fridge could probably last a day on those batteries, possibly even more. This battery bank is too small for this motorhome. I would consider getting a larger bank, perhaps 4 X L16 if you can accommodate the height. Also, you should consider the EFOY generator for quiet power. See our Tech Talk article about it: