Can a 1.8-Watt Solar Battery Maintainer help keep your car battery charged because the lack of driving? Question: I just bought a 1.8-Watt Solar Battery Maintainer because I only drive my car once per week and I have to get a new battery every 12-15 months. Can the 1.8-Watt Solar Battery Maintainer help keep my battery charged? Answer: yes that is what they are made for. It will help if u make sure u don't already have a power drain and also make sure ur battery is fully charged to start with, also check the water on the battery. A lot of ppl overlook this thing.