BatteryMINDer Model 1500CEC1B: 12Volt-1.5 Amp Battery Charger Maintenance Charger/Desulfator with Push-Button Battery Indicator - Designed for Cars, Trucks, Motorcycles, ATV, Boat, RV, etc.

I have a more expensive one from this company, but this seems to do the same for much lower cost. A reasonable cost for prolonging battery life.

Must have if you have a vehicle that's stored and not used much, or if you have a key fob that may open your trunk when the fob is in your pocket.This one works well, my trunk has opened and this kept battery charge up with trunk light on.

Update: I bought another unit for a motorcycling friend, and they discovered an issue that I had also seen but assumed I did something wrong: We left our chargers connected to our bikes for a week or so, and at the end of it, the bikes were completely dead, and the charger indicated "Polarity Reversed". Obviously this was incorrect, as the conditioner was working as expected when we first plugged it in and the charger started working again after disconnecting and reconnecting them.If it were just one device, I'd assume it was a bad device. Two of them on separate bikes in separate garages by different users says there's something wrong with this unit's design, and I can no longer recommend without significant caveats.Original review:My motorcycle battery was acting up and wouldn't hold a full charge. resulting in weak cranking, and taking a long time to start. I put this charger on over the weekend, and Monday it startled me how strong my battery was. I figured it wouldn't last (maybe it was just because it was just charged, and maybe it'd go back to being weak) but it's been a couple months, and the battery is still stronger than it ever was before this conditioner went to work.

My tender stopped working after 9 months. Called and with out question it was replaced and shipped free to replace. I had to return the old unit and fill out a form but that was it. Wish everyone stood behind their products like this. New unit is working great.

I purchased this to replace the Battery Tender that I had where the cord frayed. This one is very nice and has a longer cord, which makes it easier to get to the car battery (it's behind the drivers seat on my car).What is the difference between the Minder and Tender? This unit is more intelligent and sends pulses through the battery to de-sulfate the battery (a normal process that causes build up as the battery discharges). LED indicators make it easy to see that the unit is working. There is a quick disconnect inline in the cord so you can leave a bit in the car and just plug it in when you get home (NOTE: I don't recommend leaving the clamps attached to the battery, however).A great way to protect a battery on a vehicle that may only have seasonal use.

BROUGHT MY EXPENSIVE BATTERIES BACK FROM THE DEAD

Very good meter. I would have given it five stars except for one problem. One of the unit's battery terminals does not line up well with the positive terminal on one of the batteries you insert. When I first inserted the four 1.5 volt batteries, the meter would not go on. After moving the batteries around a bit, it finally went on. Later, after a few weeks of using it, the unit again would not go on. So I inserted a small piece of thin cardboard between the batteries and got it to work. It may have been a mechanical design flaw or perhaps a problem with my individual unit.

I was skeptical but I figured if it didn't work I could return it. The battery was below 9 volts. It wouldn't charge with my other charger, (not a desulphator). Within a couple of days I tested the voltage and it was over 13v. It settled back down to 12.6v but I'm ok with that.