I used to change lawnmower batteries almost every spring due to the cold and inactivity. I put one of these on my lawnmower 5 years ago and I still have the same battery that runs flawlessly. I also made a cable to connect a second mower and it worked great. To update; I now have 5 of these things and they have never let me down. I just ordered 6th.Update; I have a power chair with a charger that will damage the batteries if left plugged in for more than 24 hours. I ordered 2 Schumacher chargers and some Velcro. I placed a charger on the top of each battery, connected each charger to a battery, connected both chargers to a 6ft extension cord, routed the cord to the handle and now I have a built in charger that will NOT damage the batteries if it is remains connected weeks. It works great and I can plug it in anywhere that has a 110 volt outlet.