Fridge:AC=DC?

[LHaven]

Is the fridge operation on shore power entirely independent of DC?

I have a camper whose converter went plotz last night, possibly due to the strain of keeping two damaged 12 V batteries charged. When he disconnected the batteries into town to replace, he said his refrigerator went off, even though he's on shore power. Now I'm wondering whether the refrigerator relies on the converter to turn AC into DC to run its logic board, and doesn't do pure AC operation.

We managed to get his converter up and running last night after it failed the first time, so it will be nice if just replacing the batteries would keep it happy and running, but he may have to replace that as well. In the meantime, I've lent him my 1980s vintage battery charger just in case, because it's all the DC equipment I have.

[chuckster57]

Your fridge needs 12VDC to power the control board and "eyebrow". Depending on brand they will still operate down to about 11.3VDC. the AC power is only to power the electric heating element.

[sourdough]

^^^^Chuck beat me to it.

[chuckster57]

Originally Posted by sourdough

^^^^Chuck beat me to it.

for once

[LHaven]

Originally Posted by chuckster57

and "eyebrow".

Ah, that explains what he was trying to tell me about "I couldn't switch it to auto because the batteries were out." That didn't sound right to me, but now I understand it.

Auto shop in town says his batteries charged up good to 90%, so it looks like converter replacement time. I'm amazed the batteries are any good at all, because when he bought it, it was sitting in the storage lot with the emergency brake cord pulled.

[chuckster57]

I would be checking the brakes.

[LHaven]

I'll suggest it to him. He's going to be stationary for a long stretch anyway.

[sourdough]

You might tell him to keep his eye on those batteries. No telling how many discharge cycles they have been through and one, just one, total discharge reduces the recharge ability by something like 83% if I recall so he may be dealing with issues from now on if he doesn't replace them.

[chuckster57]

If the break away pin was pulled then the magnets were subjected to full battery voltage, I've seen some get lucky and others cook wiring. Simple test:

Using a multi meter, determine which wire at the break away is always hot, then use THE OTHER wire, attach a DC amp clamp and pull the pin. Brakes in good shape should pull about 14-16 amps.

[LHaven]

Last night, we performed Maintainance Method 1 on his converter ("take stuff apart and put it back together again"). We took out the two 30A spade fuses to check them, and they were both fine. We put them back in, plugged in the converter, and after maybe a 5-second pause, it kicked in, the lights came back up, and the control panel showed "full charge" (meaning only that the converter was running). But at 5 AM the CO detector started beeping again because of low voltage.

I'm wondering if there is some sort of internal resettable breaker that is kicking out because it's trying to charge two somewhat faulty 12V parallel batteries, or whether the batteries are failing because the converter is just bad. In other words, it's not clear whether to replace the batteries first or the converter first. The auto shop in town has told him his batteries are adequate.

[chuckster57]

Take the batteries out and have them LOAD TESTED. I would also do a specific gravity test on each cell.

[JRTJH]

Taking the batteries out, load testing them is the "gold standard".

Alternatively, the trailer will function without batteries, just don't energize the slides, leveling system, tongue jack or stabilizer jacks (if they're electric). As for "typical trailer DC power requirements (lights, refrigerator, furnace fan, vent fans, etc) the power center converter will provide all the power necessary for "regular trailer living".

So, disconnect the batteries completely from the trailer wiring. Isolate the battery cable terminals to prevent them from shorting out, plug the trailer into shore power and it should "function normally without a loss of DC power"... If the trailer DC power acts "normally, that will tell you whether the converter is functioning normally. If the converter power drops and the trailer DC power does not act "normally" then that would indicate the converter is not operating as it should. NOTE: Many "permanently located trailers" such as in a seasonal site, don't even have a battery connected to the trailer for years and years and they power the systems without problems.

Now, that said, if the converter does NOT function normally, the batteries may have caused the converter to fail, so BOTH the batteries AND the converter should be checked carefully to make sure they are operational.

[LHaven]

Originally Posted by JRTJH

Alternatively, the trailer will function without batteries, just don't energize the slides, leveling system, tongue jack or stabilizer jacks (if they're electric). As for "typical trailer DC power requirements (lights, refrigerator, furnace fan, vent fans, etc) the power center converter will provide all the power necessary for "regular trailer living".

Excellent. I was loathe to use the converter as a straight DC power supply without a battery to serve as a buffer, given the number of battery chargers I have seen that carry this exact warning. But if it is known to work, that makes things easier, and gives him some leeway while he takes the batteries in to the "edge of civilization" to get them load tested at an Interstate. It also (as you note) will serve as a foolproof test of whether the converter can hold its own with no bad batteries to take the blame.

[LHaven]

Last night, he disconnected both batteries, unplugged the converter for 10 minutes to reset any possible internal resettable fuses, plugged it back in, and had absolutely no DC, so a new converter is on the way. Thanks to everybody for the help.

[GIllusions]

All your posts have been very helpful for my DC problem. Nice to see people trying to help others.

[LHaven]

New (upgraded) converter successfully installed, and batteries exchanged for new ones. Thanks for the help.

[Skins44]

had the same issue with my converter, acting funny for about a year. Lights would randomly go dim, AC unit would cut out (DC stopped working with thermostat), battery level would read 1/3 all of a sudden. Then, hours later, everything was back to normal. The last straw was when my furnace cut out on a recent trip in DE. Overnight temp was 28. Figured out the converter was finally dead and not charging my batteries. Replaced converter and all is well. Misery loved company. Glad your issue is resolved! Great forum here for feedback.

[flybouy]

Originally Posted by Skins44

had the same issue with my converter, acting funny for about a year. Lights would randomly go dim, AC unit would cut out (DC stopped working with thermostat), battery level would read 1/3 all of a sudden. Then, hours later, everything was back to normal. The last straw was when my furnace cut out on a recent trip in DE. Overnight temp was 28. Figured out the converter was finally dead and not charging my batteries. Replaced converter and all is well. Misery loved company. Glad your issue is resolved! Great forum here for feedback.

Over the YEAR of issues have you had those batteries load tested? It would be a shame if a defective battery destroys your new converter.

[Skins44]

it's actually only one battery (didn't mean to type "batteries"). At first i thought it was the battery. I looked at the one that came with the camper and it wasn't a deep cycle. So, i had the dealer give me a deep cycle. Issue still continued until recently on the new deep cycle. I purchased a second deep cycle when i had the recent issue which is what is connected now. I will use my first deep cycle battery as a back up once I charge it and load test.