Mine works
I installed a new house bank, Link 20, and a West Marine Combiner on my Cat 30.I do not get any strange readings from my Link 20.Any time the combiner "sees" a charge it will combine both banks.(Use the optional wiring to a switch to manually switch the combiner). You will like being able to turn if off and on to isolate your batteries when checking systems with the Link 20.I love mine. It is nice to see the amps and voltage at a glance on both banks. I even noticed a very small short that showed as a discharge to the AMP hrs remaining. I have also checked the system with a multi-meter and the readings are all true. I have (4) Trojan T-105 batteries (in series) for my house and (2) multi purpose deep cycle batteries for the starting bank. This is hooked to a 75 amp solar charger. No problems with this system so far and I have had it installed for over a year now.