Wfco 75amp converter or inteli-power 9200

I know a guy who has the 100 watt Wfco in his toy hauler. He has never seen 14 volts charging, even on very low batteries. Even tho he had dead batteries all the time, I never did convince him that it wasn't working properly, and that it was a very slow charger. But he did add 240 watts of solar this year, to make up for the POS Wfco's dead batteries all the time.

All I know about the PD converters, is that whatever they do, they do it right !!! They make batteries last forever, and hardly need water once a year.