Replacment battery for Solar path lights

I had an issue with one of my path lights.  It was not turning on and showing offline.  I could not find the problem, but fixed the one light when I swapped the batteries, but now the other light is doing the same.  I know the battery is the issue.  If I plug the light in to charge it stays solid, but it will go back online and it notes the battery is showing 85% charged.  Not long after unplugging it the light will go back offline.  I tired to fined replacement batteries but I am not finding any that I know are in specs.  Is there a way to get repayment ones?