So I put the fan back in and the lid back on, hooked it up to the GT power meter, then connected GTpower to battery then turned on the 120vac. The voltage pot was set at 13.6v, the Screwy31 was at 12.4v and the GT power recorded a peak of 41 amps right after I flipped on the 120Vac. It dropped to 39 amps stayed there for a few seconds until the battery hit 13.6v then tapered quickly.
I then cranked the trim pot to the max and it rose back up to 38 amps, but then slowly dialed it back to 13.6v and then cut the 120vac as I want the solar to have some work to do come sunrise.
I think perhaps the pot should be near battery voltage before being cranked up and maxing out the power supply well beyond what it claims to be able to provide.
Best 23 dollars I ever spent.
