Originally Posted by
mattims
Hi,
Just a quick question on the USI-160 that I have. I have 2 x 100amp hour marine batteries (supercharge brand I think, so probably not very good, but not the worst).
They seem to be working just fine when I have my fridge running, but when I leave the car with nothing (that I know off) running for about a week when I come back to it the batteries are disconnected from each other (which I think is a normal timeout feature) and the second battery shows only 12v or just below, but the primary battery shows 12.7 and once I start the car it reconnects the batteries and charges the second battery back up (at about 65 amps initially but drops off pretty quickly within about 10 minutes it will be down to 2-5 amps).
Is this a sign that my second battery is not very healty? or just something I am not understanding about how the system works. The batteries are both only about 1 year old and the second battery has only been below 12v with my fridge running twice (not low enough to cut off with the auto low voltage cutout though). So I know that marine batteries are not really deep cycle, but I didn't think cycles down to 12v was too bad for them.
