Converter fan cycling

[LHaven]

DW and I do zero cold weather camping. However, Southern New Mexico went subfreezing this week without our permission, so we're in unfamiliar territory with our Cougar systems.

This morning, our converter fan was cycling on and off every five seconds. (at first, we thought it was our furnace, thank heavens it wasn't.) I know the converter does this when there is a big charging load on it, but I don't see where that's happening.

Right now, I have all DC loads off, except for whatever it takes to run the refrigerator board on shore power, and the fan is quiet. (My water heater is on electric only, which I don't think calls DC power to the board.) However, if I turn on as little as one LED puck, the cycling starts. The battery shows as being at 13.7, but of course that's the charging voltage being read.

Right now, it's about 38° outside. Is this behavior common in cold weather camping, or should I be suspicious of my battery?

[sourdough]

Where are you in NM? You are probably pretty near the temps we are running here at home so it's not a real big deal. The nights in the upper 20s could be problematic for your water hose if it's not heated. What kind of shape are your batteries in? Your converter is trying to charge them and keep whatever you have going in the trailer running including control boards etc. Almost sounds like the batteries may be low and the converter is carrying the load. Your furnace fan runs off the batteries (or converter) so if it's running a lot it could be affecting the run time on the converter. Another thought that made a difference in my last trailer; are all your lights LED? I suspect so but if not they make a big difference in the converter running as well.

[NH_Bulldog]

I am leaning toward the battery(s) myself. Cold temps will really test a battery that otherwise “acts” normal in warmer temperatures.

[LHaven]

We spent the night in Deming. We didn't hook up the hose because we knew it would freeze, so we just ran off our tank. All our lights are LED. I did realize after sending my post that I had forgotten we had turned on the freshwater tank heater overnight, so that was probably a major load. Before leaving this morning, after we had unhooked from shore power, I read the battery voltage and it was 12.9, so I think this is probably just a false alarm.

[NH_Bulldog]

Ahhhh, tank heaters makes sense. I didn’t consider that possibility since you said all the DC loads were off. With any luck, that was the load on the converter and you are all set!

I have never kicked the tank heaters on until temps are in the mid to upper 20’s for more than 24 hours, otherwise the furnace keeps the belly area above freezing. I don’t camp at those temps often, but we have been caught by surprise a few times.

[sourdough]

Yep, tank heater(s) were probably the culprit. I've turned mine on once. Like Rob I don't turn them on unless I'm going to have very cold temps for an extended period or mid 20s/lower for over 24 hours. Glad you figured it out.

[Bill-2020]

Ah, Deming... Brings back many a midnight run to Tucson from ABQ. I recall highway 26 between Hatch and Demming. Pitch black except for the moon and two lanes until you met up with I-10. Good times.

[LHaven]

Just did Highway 26 today, re-viewed one of my favorite road signs:
NUTT 28
HATCH 46

[Bill-2020]

Originally Posted by LHaven

Just did Highway 26 today, re-viewed one of my favorite road signs:
NUTT 28
HATCH 46

I had forgotten about Nutt!

[skids]

I'll bet the demand on the 12v system is caused by the furnace fan.

[LHaven]

Furnace wasn't enabled (when outdoor temp is over 40° our $20 Tractor Supply ceramic is able to shoulder the entire heating load).