I made one to charge dewalt and ryobi batteries 20v and 18v lithiums. . I have found 100w is not enough in Ohio. The 12volt chargers I am using pull 6 solid amps at 13 volts. I used 2 x 100 watt panels, a 5 farad capacitor "battery" and a 30 amp mppt controller. It works great. I wired the panels in series so this gives it about 40 volts open circuit. This seems to work well on the half cloudy days. Your old battery will be fine as long as you have enough solar coming in to maintain 6 amps at 13v. Good luck and happy experimenting.
r ranson wrote:
People keep calling me an influencer or saying they did or bought a thing because of something I said online. That kind of worries me. So I take it and use it to create the kind of thing I want to see more of on the internet.