Furnace draws down aux battery when plugged into 110

Yes, you can be on shore power and getting 120v to run things but still be on battery for the 12v things if the converter is not "on"

BTW the fridge will not work on 120v if it does not have 12v to run the controls, so you will lose the fridge too fairly soon at this rate as the battery runs right down.

There are several reasons why that could be. EG, you might have accidentally reversed the battery wires the last time you installed the battery, which blows the two 30a fuses on the converter or its nearby Dc fuse panel.

Or the converter is not getting any 120v input if it has its own breaker and it has popped. Or it is not plugged in to its receptacle if it has a cord and is not hard wired. Or that receptacle is on a GFCI protected circuit and the GFCI has popped. Or...

BFL13 wrote:
Yes, you can be on shore power and getting 120v to run things but still be on battery for the 12v things if the converter is not "on"

BTW the fridge will not work on 120v if it does not have 12v to run the controls, so you will lose the fridge too fairly soon at this rate as the battery runs right down.

There are several reasons why that could be. EG, you might have accidentally reversed the battery wires the last time you installed the battery, which blows the two 30a fuses on the converter or its nearby Dc fuse panel.

Or the converter is not getting any 120v input if it has its own breaker and it has popped. Or it is not plugged in to its receptacle if it has a cord and is not hard wired. Or that receptacle is on a GFCI protected circuit and the GFCI has popped. Or...

X2

All of the suggestions above are valid. You'll just have to do some looking and double checking until you find the cause.

The thing that got me exactly the same as you... I had four days of plug in camping, and then boondocked and had no battery power.

I ended up wiggling the wires from the converter output, and then all of a sudden the DW says, "Wow, the lights just got bright!" I had my culprit and just had to tighten up the screw holding the negative return wire.

The thing that helped me figure it out was when I was driving, the batteries charged, but when I was plugged in they didn't. I checked the converter output at it's output and it looked good, but at the battery there was almost nothing.

If there is a bad connection on the converter to battery paths, then you will also have trouble getting proper battery 12v voltage to your DC distribution (fuse) panel to run the 12v things on that. (Unless the bad connection is between the converter and the dist panel.)

W/o more info, the most likely cause is a bad converter.

Pretty scanty info.

What do the lights do when the furnace gets PMS?

If I had your problem the first thing I would do is check the battery voltage, with the furnace off, first with the 120v unplugged then with the rig plugged in. The voltage should increase with the rig plugged in. Exactly what it should increase to depends on your converter and the battery state of charge.

Lacking a volt meter, have someone plug in the rig while you watch the lights. They should get brighter when plugged in.

The next step depends on the results of this test.

Wow folks, I thank you for all the info. I will do some checking today. I'll post my findings when I'm done.

well i've checked all the connections i can find. all tight and clean. when i unplug the 110 the lights dim. i checked batt voltage unplugged from 110, 11.00 volts. measures the same with 110 plugged in. checked battery voltage with generator running, 11.00 volts. started engine and checked voltage at batery, 13.65. only charges from engine alt. lacking any evidence of broken/disconnected wires i think i have a bad converter. i can hear the transformer humming when plugged into 110. any other thoughts before i spend hard earned cash on a new converter? thanks for all your help. tim

Check the converter DC output when connected to shore power/generator
S/B 13.2V DC minimum output. Otherwise replace converter