Many times we think our maintainance free batteries are just that. But they ain't. Make certain yours doesn't have cell caps for adding water. If yes fill as required. In addition to checking the no-load voltage, you should check the specific gravity using a hydrometer. The S.G. should be at least 1.275 with all cells even. If difference of 0.25 after battery has been charged, the battery is defective and should be replaced. Happy Trails Beep Beep from Houston.

Donald
fully loaded
no dead cells on me