Ask PYS: Power

Fred, on Dec 09, 2011 asked:

I have a 2007 formula 31 PC. I currently have four 6V flooded golf cart batteries totalling 464Ah. I also have a 7.3kW genset with a transfer switch at my main panel between shore power and generator. I have a 60A battery charger mounted in my engine compartment. I am looking to install an inverter/charger. I don't seem to have enough charging capacity as I seem to have to run my genset for hours after getting down over 100Ah.

Hi Fred,

When your battery bank is down to only 100 Ah, it is very near the absorption stage (85% to 100% of battery capacity) of the charger. Your fastest charging (25% of capacity) will occur at bulk stage (50% to 85% of battery capacity). When at anchor, you should be in the bulk charging range so that your charger is the most effective.