I have looked at battery maintainers for a long time to see what the best ones are. So I finally bought 2 Battery Minders and 2 Battery Tenders. These are suppose to be the 2 top rated brands on the market. The battery minder gives the extra benefit to desulfate a battery. Then I saw this at Eastwood, It has all of the features of the 2 top brands with an extra feature of 10 Amp Charging and Desulfating. So I hooked it up and measured the voltage during the different stages of charging. It cycles through the stages at the exact same voltages as the 2 other brands I own. The other 2 are not really for large automotive batteries because of the low amperage of .75 amps and 1.25 amps. The battery Sustainer has has 2 AMPS and 10 AMPS, plus a cigarette lighter adapter. I have used on 3 different batteries and it works EXACTLY like the 2 top brands, But much faster with the 10 amp charge. It is now my Favorite. I will buy another one. The L.E.D. readout gives much more detail than the others. I bought others, before these but most of the others charge at too high of a voltage, and worked very slowly. Trickle chargers are a thing of the past, in time they will ruin a battery. You need the Float charge feature of the Sustainer to be able to leave it on for long periods of time. This is the best deal on the market with the quality of the top name brands.