Yeah, well, you get what you pay for.
I "suspected" that GT needs switching to work both ways, and mentioned this earlier.
mtnman should better wire it to measure "out" flow, i.e. from battery to loads. Then he'll know how much charge the battery has lost overnight after controller had brought it to Float the day before.
People think they can measure battery state of charge by looking at the voltage. This would be a close guestimate, but only in the morning, before controller kicks in. In the daytime, with controller working, even without loads, the voltage can only tell you that it's somewhere before or after the 14.4 peak. Or at the peak. But then, most cheap controllers have LED indicator for this.