Keep riding mower battery fully charged with solar.

I keep the batteries on my riding lawn mower and my DR brush hog fully charged all the time. I purchased one of the inexpensive solar panels for each, available on okay. They are made to keep a car battery charged, the panels are about 4"x10", and they work great. Just clip the cigarette lighter plug from the wire, noting which wire side is positive. Extend the wire with more wire