I know this has been discussed before but I am confused. I installed a smart charger IOTA converter charger and the house batteries stay perfect. But after a week plugged into 50 amp shore power the engine chassis batteries are dead. I know I have drain from dash stereo system, etc. I thought there is either a way to charge both sets of batteries ( 2 8d starting batteries and 4 Golf Cart Trojans for house) while parked. What am I missing or what is likely failed to prevent all batteries being maintained while parked?
Thanks in advance.

Some convertors have dual outputs to charge both sets of batteries.... I have had the same problems as you.... Being a simple person, I just hooked up a small battery charger to the engine batteries and plugged it into the outlet that is for the diesel block heater ( unplugged heater, plugged in charger..outlet is controlled by a switch above drivers left shoulder..) simple and cheap...

On my 74 there is a 4 post solenoid switch I use a set alligator clips to bypass two of the posts...not really sure how or why it works but it's the only I can charge the chassis batteries.the trick was showed to me by a mobile rv repair guy I use....hope that helps some.

First, there's more afoot than just dash radio drain (although I rewired mine to the house battery). With 2x8Ds, the radio shouldn't discharge the chassis battery for months. A test of the chassis batteries, and a check for drain, is in order. A bad diode in the alternator can cause that issue.

There are "vampire" chargers that connect to the house batteries to charge the chassis battery, but I think something else is involved.

Thanks to all. On my coach the block heater is hard wired to the switch, no plug in is available. As on some others the Barth binder had a warning that to avoid overcharging the coach was wired to the cold side of a solenoid and that leaving it in Run position would otherwise continually charge the chassis batteries. I have not figured out what or where that solenoid is,but I suspect that is the problem. I would like to rewire but with no schematics or wire routing diagrams I am trying to see what others have done. I can, but would like to avoid tracing every wire, if I can.

On my coach there was a switch on the instrument panel labelled "Aux Start" It was a momentary contact type used to jump the batteries while starting.

My coach also has an alternator that does not remote sense, connected through a diode splitter to charge both sets from the engine. Problem is, there is a 0.6 volt drop across the diodes and the batteries were always .6V lower than ideal, chronically undercharged.

I removed the diode splitter and momentary relay and installed a constant duty relay. Now when I leave the switch on the batteries see full charge voltage while driving. Also good way to charge the start batts from shore power.

Normally the alternator keeps the start batts happy and the house batteries can be topped off underway if needed. The Prog Dynamics charger does a good job while parked.

The solenoid you mentioned sounds like what I have now. I don't know where it is on your chassis, though.

I use a small device that connects to the house battery's and will only charge the starting batteries above 13 volts, so it is active plugged in and off normally. I had the same problem before.

The best choice to solve this issue is a 1315-200 Sure Power battery separator. We stock them. The unit is bi-directional so it senses the voltage from both the starting batteries and the house batteries. No matter what the charging source alternator or converter the separator makes sure all the batteries are kept charged. The down side of a constant duty solenoid is the "in-rush" voltage the comes from tying all the batteries together at once. The 1315-200 phases in the battery connection so it does not overload any component. This particularly important to the alternator. My business is Smith Auto Electric, Yakima,Wa www.smithae.com 800-822-0819