I have 4 Trojans, all of which are new. A few months ago, only two were new and the same thing happened. While the old batteries still tested good, they seemed to charge constantly, even when there was nothing turned on and the SG reading was 1.275 or higher. After replacing the old ones with new, the problem ceased to exist. The manufacturer didn't have an answer for me, but now I no longer worry about overcharging with the solar system.