Low voltage at atwood rv heater, help please

Your battery, converter, and supply wiring are all parts of one 12V system. You need to find out if the converter is working and if the battery is usable.

With a voltmeter, measure across the two battery terminals without the 120V shore cord connected to a supply. You said you have 12V but I would check it again. If it is 12V, that is less than 50% charged. Next, connect to shore supply with your shore cord and measure again across the battery terminals. You should measure at least 13V. If not, there is a problem with the converter, open fuses at the converter, or a tripped circuit breaker between the converter and battery.

Initial diagnosis is that your converter is not outputting charge voltage. Check the 120V circuit breaker that powers it and measure for DC voltage at the outputs.

Are you saying that when plugged into shore power that the battery still reads 12 volts? If so maybe your battery is pulling everything down. When plugged into shore power your battery should be over 13 volts. Either the battery is pulling it down or it isn't charging properly. The battery 12 volt problem is not a separate problem. It is all linked.

Your converter is not working. Voltage with converter working should be 13-13.5 VDC.

Merry Christmas. I hope it's not too cold without furnace running.

Your battery is not capable of running this load at the moment. This is why it drops to 10.6 under load. It is deeply discharged - less than 50% remaining. Could be even less than 40%. When they are getting older, they have problems keeping 12-something volt under load when discharged that deep. But you should still be able to see 13V on the battery terminals because 13V is coming from converter - so I concur with Westend, your converter isn't charging the battery.

I am pretty sure that the battery charging component of my converter isn't working, although I am not sure how or where to test that. I have the cover off and am looking at the cooling fan, etc, but done fully understand everything I am seeing.

As far as I can tell the only way my house battery charges right now is with the vehicle running. I had a problem with that as well and found that the ? Control Switch? that allows power to flow from the auto battery/alternator to the house battery, but not the other way, had failed. Also, the wire from the auto battery to this switch had corrosion and wasn't letting voltage through. Those items are repaired/replaced, but I haven't gotten my battery back up to a full charge yet (charger not working?? ).

Thanks for helping me work through this. I think I am close to answers but need a little more assistance. ....

If you have restored the connection from house battery to alternator, it should be able to charge the battery but it will take a looong time, especially with furnace running. The wire in 7-pin plug from truck to trailer can only carry 8 Amp, and your furnace it drawing about that much.

Okay. So I'm slowly recharging my house battery from my car battery. By the way, this is a class c four winds Ford 350 motorhome, with one house battry in the engine compartment.

While I am hopeful my house battery will fully recharge (living full time, driving every day, but very little, like maybe for an hour), I have concerns the battery may need replacing. That all being said.....

I am thinking the low voltage problem at the heater, and the rv power panel while on shore power (with the most likely, but not sure, not working battery charger part) is separate (mostly) from the house battery issues I've had. I am thinking that since I am on shore power, I should see full volatage at the furnace blower motor. Or if the house battery somehow interferes with this, at least the 12v I see at the house battery, instead of the 10.6 I get, or the 10 with lights on. So I am still wondering, and really hoping someone knows to tell me, if I am seeing a voltage drop from that white ground wire.

How do I test the converter to see if the converter part is fully working? And how do I test the battery charging component of it? Or is the system so integrated that it is not possible to test them separately?

Does what I'm thinking make sense?

"...10.6 reading when plugged into shore power. Furthur testing at the rv power distribution panel/fuse panel gives me a similar reading when I test from the blue shore power line attached to the 12v panel to the white ground input coming from my house battery..."

The converter (some of them) has a blue (positive) and a white (negative) wire which is the Dc "12v" output to the fuse panel. With shore power plugged in, that should provide the converter with its 120v AC input and the blue and white output should be about 13.6v DC.

The battery also supplies "12v" to that fuse panel and the converter charges the battery going the other way so at the battery posts you should also be seeing 13.6v when shore power is plugged in.

Your converter is not making any "12v" so all you are getting for "12v" is a dying battery doing that.

The converter may not be getting any 120v input even though the rig is plugged in. Or it is but has an internal fault so no 12v output.

On the fuse panel or on the converter itself, look for two 30a DC fuses. If they or one of them is blown, that is one way this can be happening. Those are "reverse polarity" fuses which blow if you hook up the battery backwards. The battery will still run lights ok backwards but the fans will rotate the wrong way.

Your converter should be supplying 13.2 volts while plugged into shore power.

I think if you solve that problem, then low voltage at the appliances should also be solved at the same time.

What is the exact voltage at your battery?

Do you have a portable battery charger that you can put on the battery to raise it's voltage a bit? Once the battery is full, many portable chargers can put out 15 volts, surely enough to run the water heater.

If nothing else, then try plugging in the RV to a truck, and let it's engine charge the battery for a while. Then all the appliances will run while on the vehicle engine charger.



Good luck,

Fred.

Ok, BFL13. I am seeing the blue wire and white wire coming from the converter area and going up to the 12v fuse panel. The blue clearly connects to the face of the panel. The white one connecta somewhere on the back, which looks a little difficult to access to me. However, I see where I can poke them after they exit the components of the converter before they head up to the fuse panel. When I do so, I get 10.7v. Hmmm. I am thinking this is bad news.

On my 120v circuit panel, I have a breaker for the converter. I switch it off, and the converter stops the slight humming it makes. When I turn it on, it starts again. So. There is that information.

Based on what you were saying, is it possible there is another, or other, fuse(s) hiding somewhere in/on the converter that I am not yet seeing? I am hoping so as I really don't want to have to replace the whole unit.

Again, thank you all for your help and guidance.