About 8 years ago I mounted a small 4W solar panel to my shed to keep the 12V flooded lead acid battery charged on my infrequently used tractor. The solar panel has worked great without any problems. I just replaced the tractor's 10 year old battery with one with more cold cranking amps for the upcoming winter. The old battery has been out of the tractor for about a month and it still reads 13.1 volts. I know a fully charged battery should be about 12.6V. Why is this old battery so high? Have I been overcharging all these years? I thought I did not need a charge controller when using any small panel less than 5W. Is that true? Further research suggests 2w or less for each 50 battery amp-hours is fine without a controller and a typical small start battery is only 45 Ah so perhaps I have been overcharging. Any suggestions?