9 replies to this topic

[PMills]

While on shore-power, furnace works well on our 2006 Four Wheel Camper.  On house battery system, insufficient power gets to furnace fan to run at necessary RPMs to activate furnace.  In trying to diagnose issues have noted several symptoms:  when on battery power, right side of camper (i.e. ceiling light on) electrical system shows "green" and battery good; however, when any electrical draw from the left side of the camper (i.e. ceiling light over kitchen is on), the electrical system shows "red" and charging of system required.  This occurs even when the truck engine is on and charging the system. Have changed the battery twice and have kept it on shore-power trickle charge, yet problem continues.

We're looking for guidance as to next steps?!?!

[esimmers]

It sounds like everything including the furnace works well on shore power but not on battery because on battery power alone the furnace needs more watts than the battery can supply. So let's start out by getting some more information about why that is.

 

 

If I had to guess one thing, I'd say that when on battery power something, probably the refrigerator, is putting such a high amperage load on your battery that the furnace doesn't get what it needs to run properly. One easy test is to turn off everything in the camper except the furnace and see if the furnace runs properly when the battery is fully charged. For instance, if you have a 3-way refrigerator and it's set to be powered by DC when on battery power, be sure to turn the refrigerator off when you do this test. That's because a 3-way refrigerator pulls a huge amperage load that will quickly run the battery down even if the truck is trying to charge it. 

 

If that's not the problem, gather some more information. When you think the battery is fully charged, make sure that it is by letting it sit for at least half an hour after disconnecting one battery terminal to make sure there's no load on the battery while it's resting. The battery voltage should be at least 12.6 volts at rest if it's fully charged. If it's not, then something's wrong with the battery charging system as the battery isn't being fully charged. I don't know what sort of battery charge meter you have with the red and green light, but those systems are not accurate enough to tell you much. They measure voltage alone and changing from green to red shows there's enough current draw to cause the battery voltage to drop, but that's not much help.

 

It's odd about the two ceiling lights and their effect on the red/green charge meter. Both lights are on the same circuit fed by the wires running to the ceiling behind the front lifting board. Maybe the one over the kitchen is somehow drawing a lot more amperage than the light on the passenger side, but that seems quite odd. You could test the battery voltage when each light is on in turn; the voltage drop, if any is seen, should be the same if the fixtures and bulbs are similar.

 

You don't say if you're able to run the furnace of both lights are off. Can you?

 

So the problem again is either too much battery load when not on shore power or the battery isn't getting fully charged.

 

The third possibility is that there's a poor electrical connection somewhere between the shore power battery charger and the battery. I assume you have an Iota charger that takes the 120 volt shore power and converts it to 12 volt DC to both charge the battery and run all the 12v appliances. Since the battery charges at a much lower rate than the furnace draws power, it could be a partially-broken wire or bad connection leading to the battery that lets enough electricity through to charge the battery but is inadequate for the load from the battery needed to power the furnace.

 

I hope you have a voltmeter. Nothing fancy, but it's a vital tool for situations like this.

 

Keep us posted.

[pvstoy]

Nice analysis with the provided information.... I like your thought process and wording, much better than I can do.

 

It is also noted that the OP has changed the battery twice, I'm thinking that the 3 way refrigerator has been running on high amp DC mode, causing the battery to go flat.  Even on shore power the Iota can't keep up and perform a charge on the battery if the refrigerator is still switched on DC volts.  refrigerator draws around 10 amps.

 

Or there could be a short in the system that is causing a high drain.  

 

Once the camper battery is too far down on volts the Battery Separator wont engage to allow camper battery to get charged from the truck alternator. 

 

Keep us posted......

[Vic Harder]

Good ideas given already, so I will just ask, did it work before?  What changed, if anything, before it stopped working?

[Mighty Dodge Ram]

You’ll certainly want to sort out your electrical issues first. But something to consider: once you’ve fixed the electrical gremlins why not run your 3-way fridge solely on LPG? I do this in our motorhome after discovering that 12v and 110v power do not adequately heat the ammonia in the system. The fridge stays much colder on gas rather than electricity. This would free up power for other uses. This is not an issue with the Dometic model I use in the pickup. The small, efficient compressor uses a manageable amount of power. Good luck with the fix.

Edited by Mighty Dodge Ram, 05 June 2019 - 04:41 PM.

[pvstoy]

We are only speculating the the OP has a 3 way refrigerator and expanding the possibilities.  They may not even have a 3 way refrig as we have not hear back with any feed back for their second posting.

 

As you, with our past rv's I only used propane from departure to return.

[Stan@FourWheel]

Not enough air flow and a slow furnace fan speed was common on those old Suburban furnaces.

 

When the camper is plugged into shore power, the furnace fan is running full speed, and going fast enough to trip the sail switch.

 

When the camper is cold (cold weather), the camper battery won't have as much usable power as it would on a warm day, and without the "boost" of full power from a 120V shore power supply, the furnace fan would not always be running fast enough to trip the sail switch.

 

If it happens / when it happens again, try removing the furnace vent cover (on the inside of the camper), starting the truck for a minute and leave the truck running, look inside the front of the furnace and "reset" the small reset switch inside there (turn it off, count to 10, and turn it back on), and then see if the furnace fires up (while the truck is still running, and the furnace vent cover is still removed).

 

If the furnace fires up, your camper battery is not putting out enough power to trip the sail switch or the furnace is starving for air. Look in the back of the furnace with a flashlight and see if the sail switch is moving freely, lubricate it if possible (hard to do), or give the furnace more air flow (open up cabinet doors slightly when camping, leave furnace vent cover off while camping, or use a small hole saw and put some venting holes in the dividing wall between the furnace and the kitchen cabinet (so the furnace can get better air flow, and the sail switch will move more towards connecting on its own).

[Mighty Dodge Ram]

pvstoy: right you are! I re-read the thread and the mention of a 3-way was in a response, not the OP. I assumed...oops, you know what happens when we assume. 🤦‍♂️ Following for more info from the OP.

[PMills]

Thanks to all who responded to my original post.  I've created a "checklist" from your suggestions and will begin, what will hopefully be, the elimination process to solution. 

 

During this last trip, the 3-way refrigerator remained on LPG throughout the entire journey, functioned well, and did not draw from the electrical system at all.

 

Anyway, I'll be working through the recommendations...fingers crossed! Again, thanks and I'll post on the forum the final outcome(s).

[Old Crow]

Thanks to all who responded to my original post.  I've created a "checklist" from your suggestions and will begin, what will hopefully be, the elimination process to solution. 

 

During this last trip, the 3-way refrigerator remained on LPG throughout the entire journey, functioned well, and did not draw from the electrical system at all.

 

Anyway, I'll be working through the recommendations...fingers crossed! Again, thanks and I'll post on the forum the final outcome(s).

 

     It would be very useful to those trying to help you (and to you, I'd think) to see what the battery voltage levels are under the conditions you describe.

 

     If you don't currently have any way to do that, an easy, non-technical solution would be to plug a digital voltage display into the camper's 12-volt (cigarette-lighter-style) socket.  That socket is connected to your camper's battery so the display would show you the battery's voltage at the moment (within a tenth of a volt or so). 

 

     That voltage will change as you do things like turn on the furnace, plug in to shorepower, etc.  If, for example, you observe the battery's voltage level with the truck off and then start the truck, you can see what additional voltage is being applied to the camper's battery (if any!) to charge it.   

 

     I use an Innova 3721 Battery Monitor and in fact have one in each vehicle and the camper.  The display window is simply a digital display of the current voltage measurement but it also has small LEDs and info on it (and on its packaging) to help us understand typical voltage ranges for a vehicle's battery and alternator.  You can, of course, use any such digital display (i.e., one with a cigarette-lighter plug).  The key thing is to get the voltage reading.

 

. 

Edited by Old Crow, 10 June 2019 - 07:16 PM.