Automatically reduces the voltage after the battery is charged. With it, you can put a car or motorcycle in seasonal or long-term storage and it will maintain a full charge of the battery, recharging the self-discharge of the battery . p s. I dropped it into a deep bat (5 meters) from a stool on which it was charging while charging the car, I removed the terminals and went to shchima, since there was a switch, I think let the car warm up until I remove the charger, the stool from the hood, and then when the ignition is on the radio tape recorder was screaming (I did not find a single radio tape recorder that, like Blaupunkt, would have a starting volume, and at the start it always started playing from the starting volume, and if I listened to music loudly in the evening, then in the morning it will not scream, but will sing at the starting volume, which I made on 1; in Sony, kenwood, pioneer there is no such function, apparently all of them are designed by pensioners, they are turned off by pensioners, I arrived, made the radio quieter, then turned off the ignition . ), as a result, while I was struggling with the radio, I forgot about the stool and started out of the garage, knocking down a stool and dropping Vympel57 into the ajar hatch of the bat . It works, only the plastic handle cracked and began to fly off, while strengthening it, bit off half of the axis for the handle - you can see in the photo . It didn’t affect work, everything charges, everything shows, well, a good charger and everything is visible and everything is regulated! still they would make a screen scroller, otherwise sometimes you sit waiting for the screen to scroll there auto .