I have 4 batteries in my bathroom for the winter...
I use a Die Hard maintainer/charger. Got it on sale last year for $17. I have a 12 volt lighter type plug installed by the battery switch. It serves 2 purposes. I use it for the air pump and then when I want to, I charge the batteries through it. It comes with the lighter plug, the pigtail to hard wire on the battery or clamps. It's on sale right now for 20. Comes with a 3 year warranty.
http://www.sears.com/shc/s/p_10153_12605_02871219000P?prdNo=8&blockNo=8&blockType=L8
"Quote of theYear"
:biggrinjester: