Trace Engineering makes this non user friendly controller. It has a setting for the amp hr ratings of your batteries. Your choices are Auto, 125, 250, 375, 500 and 1000. I have it set on Auto but was told by an RV tech that it should be set on 375. The 4, 6 volt Trojan T-105 batteries are rated at 225 amp hr. Why would you need any setting other than Auto?