Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 11, 2025 ...

This COULD explain it all...

Salesman switch does not MAKE electricity, it just connects house battery bank to coach for lights, gen start, water pump, etc.  When switch is off nothing will be powered.  When switch is on, IF battery is completely dead / empty, nothing will work.

IF house batteries are dead / empty and damaged it is the same as if they are not in the coach.

When switch is on and engine is running, alternator generates electricity that flows though the isolator to power all coach things.  When engine is turned off, nothing will work.

When plugged into shore power the inverter/charger will generate electricity that powers all coach things.  When shore power is disconnected, nothing will work

As to the voltage from charging sources:

Alternator has about correct voltage which means it is working ok and likely will not damage any electronics or working batteries.

Battery charger at 17 volts is incorrect and way too high and left alone for a long time, would likely damage house batteries, and start battery bank if connected to house bank. 

17 volts could come from charger being at an equalize setting, but likely is from a failed charger.  While we don't know why charger is putting out 17 volts, you do have a possible answer to your symptoms so well described.

If you have multiple house batteries, try to run with just one battery at a time.

Try to use a stand alone battery charger connected to house batteries.

Try to temporarily use just a different battery in place of house batteries, but be aware 17 volts if still coming out of charger, will damage a new battery.  So maybe better to install a different battery (any size, from car or start bank) and a stand alone charger.

Good luck.

Jim, I was generalizing about the salesman switch, and you are correct that it does not power the genset.

Actually years ago, we removed our salesman switch which was mounted on rear-side of step.  We learned that the two large salesman switch cables are both sourced on the top of the 12-volt bay-wall breaker panel behind the big large white cover.  We disconnected both cables at the breaker panel and put a short jumper across the connections.

We wanted to cut a large hole on step wall for access to the air fitting on the air bag located on the other side of the step wall and found the heavy duty cables and switch were in the way, and with the disconnected switch, we had a clear shot at the air bag.  We were changing all 8 air bags and the two front bags were easier to change with our access holes.

Over the last 20 years, we never used our salesman switch and figured we would later put it back in action on the bay wall connection.  Also figured there must be some voltage drop on the pair of very long cables, so removing approx. 40 feet of cable, replacing it with 4 inches could benefit us.

A month ago, we put the salesman switch on the main ground house battery to fully disconnect the battery bank when storing our motorhome.

Before taking out the 12V cutoff at the steps, you might see what actually runs thru that 90 amp breaker.  For instance my solar, as most are, is wired directly to the house battery, not thru the 12V panel in the bay.  I like being able to leave for a few hours, easily cutting off most of the 12V draw, and not having to run around the rv making sure all the 12V is off, ceiling fans, water pump, closet light, bathroom light, etc.  I also have a ground cutoff off on both chassis and house batteries for when I'm away longer and wish to cut everything on that bank off.

Thanks Jack, but I have the PMC Intellitec system with a several control buttons around coach that basically turn off all 12 volt loads [except water pump]. I would keep the breaker, just remove the switch and its wiring.

Here is a brief update. Disconnected the charge/inverter and charged batteries and load tested. While showing 12 volts they failed the load test. Have ordered to new 8d gell batteries and will install. I plan to reconnect charger/inverter and measure voltage from charger. If still high i will replace with a new one. Maybe the charger was sending high voltage because batteries were dead.

Just remember, anything over about 14.2 volts [max bulk charge voltage for most gel cells] will damage your new batteries.

Eric at bio benefit inverter repair in Costa Mesa, can rebuild heart freedom 25's completely and coats the boards and retightens the many connections internally and replaces the contactors as they pit and reduce the oiutout power to the batteries. $800 flat rate charge. 

Newer magnums use stainless bolts to lessen the corrosion in the older units and have a needed BTMS and are sine wave output and have coated boards to help prevent shorts.

The reduced output may match your dual battery setup.  Mine was maxed at 70 Amos into three 8g8d's.  New magnum is 110 amps in bulk

Call Eric and ask him about the 17 volts after resetting the dip,switch if it continues

As some of you have suggested, I am taking mine in to be repaired. A xantrex repair shop in Bradenton claims he knows whats wrong and can fix with same day service. Cost $275.00. Says these old units are well built and when repaired will give me years of good service. I have remove the unit and labeled all the wires reinstall should go pretty easy.