I have 8 or 10 or 12 of them, Dave. Some are at least 5 years old and no problem thus far. Most of mine are purchased from Wal Mart. Some have the Schumacher name on them and some have the Ever Start name, but they are all the same. Cost at purchase was around $ 14.99 back when and maybe $16.99 more recently. The way prices are jumping this year, they may be more.
At any rate, they are switchable from 6 to 12V. If a battery is down a 1.5A charge is delivered. When the charger senses the battery is full charge, it switches to a Ma maintenance charge. They have indicator lights to tell you which state of charge it is in. I have made connectors to hook as many as four batteries to one charger for over the winter and that works fine too.
I also have two of the little transformer powered units from Harbor Freight. They are not very impressive, although I guess they do work.
Hope this is helpful.
Charlie V. in WNY