Let me first say that this TOPAC 3.5/7A 6/12 volt automatic car battery charger works well and seems to be doing a good job. BUT it's far from automatic, it doesn't work for maintenance or charging. If there is a possibility of power failure, it will not restart or restart when power is restored. It must be switched on again manually! It just sits there reading the battery voltage so I'm giving mine back it's useless for my needs. My batteries last for months and if the power goes out nobody can reset the device. Hope this helps someone with a severe aggravation.