Battery Charging Question
The pictured Sears "Fully-Automatic" charger is not a 3-Stage unit. It''s a fast charger that throttles back to a "trickle charge". There are some different strategies for sensing the voltage at which to throttle back. I''m not certain which this unit uses - but I would NOT recommend leaving this charger permanently connected (there are a number of imortant reasons) !!!
The best Chargers cost over $250 (up to $400); but there are cheaper alternatives that would seem to match your fairly limited demands:
BoatUS currently has a “special” Sale ($29.99) on the Guest Charge-Pro http://www.boatus-store.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=20002&langId=-1&catalogId=20002&productId=14756
Charge Pro Portable Battery Chargers
This handy, portable, three-stage electronic charger features built-in thermal and overload protection, reverse polarity protection and LED ready indicators, so you''ll know when you''re ready to roll. The unit comes prewired with a 6 ft. AC cord and 4 ft. DC outputs.
You could permanently wire this unit (/w a breaker or fuse).