The battery tenders do work well. My Dad has a few, he has one connected to his Fusion, that doesn't get driven as much now that he and Mom are both retired. It now sits for weeks at at time. Last time he wanted to drive it, it wouldn't start. Now with the tender, its not an issue. He also has them on a couple of IH Cub Cadets and his generator. A couple of things this has done, in the winter, they will start right up, in the past, they would need at least jump, and at times some "help" into the carb.... The batteries are also lasting much longer. In the past, he would only get a couple of years out of a battery, now he gets a few years out of them. His garage is detached, unfinished and not 100% wind tight. So this is a huge improvement. I will attest the cold does kill the small batteries quickly. I've had one garden tractor battery in one of my IH Cub Cadets and it gets stored in my attached, finished and somewhat climate controlled garage (the HVAC is in the garage, and it "leaks") and it has working for almost 8 years........