Got one of these on Amazon for less than $20
"Schumacher SEM-1562A 1.5 Amp Speed Charge Maintainer"
Put on some PowerPole connectors
http://www.g0hwc.com/images/AndersonPowerpole2.jpg
just in case I forget the charger is plugged in, and back out of the garage!
It runs the battery (on the Ford Escape) up to 14.4 volts while charging and holds it at about 13.2 while in maintain mode.
It doesn't use much power in maintain mode(2.8W), but in charge mode it uses 7 to 10 watts.
It only stays in charge mode while the battery is recovering from a discharge,
caused by a discharge usage (vampire load) or plain old self-discharge that occurs naturally with LA batteries.
I have not yet measured the vampire loading in the Escape.
When first connected to the battery, the Escape boots-up and flashes the running lights. Zapping the 8A fuse in my little meter..