no power

[Tone4181]

hello everyone, I have a 2004 Jayco flight 29BH trailer and just today I went to use it and noticed no power condition on the d.c. side. all a.c. plugs work fine I am connected to 30A shore power , fridge doesn't work either now. The 2 30amp fuses on the panel below the fridge were blown , tried to replace but blew straight away. Battery is also dead. does this sound like a converter issue ?
Thanks in advance.

[RedHorse1]

Make sure the battery is connected correctly.

[DrSmart]

How old is the battery?

[Tone4181]

Battery is 3 years old . I have only been a way from the trailer for a week when this started happening , and I hadn't touched anything inc the battery. the reason I am thinking its the converter is even if the battery was low shore power would power all the d.c. stuff>

[DrSmart]

You're may be right about the converter.

[ALJO]

Never assume things, test things to be sure.

[Tone4181]

How do you think I should go about testing?

[RedHorse1]

What are the 30A fuses that blow protecting? Fuses are on the 12V side. And it seems odd they are failing. Maybe the converter has failed as you suggest.

[Tone4181]

I tried to put a picture of the fuse panel but cant figure it out . They both say reverse polarity, all the other fuses are ok.

[RetiredOne]

If they are the reverse polarity fuses, did you disconnect the cables at the battery and accidentally reattach one of them on the wrong terminal?

[JimD]

If the reverse polarity fuses are blowing then either the battery or the converter is wired backwards. That is what the fuses are for. My converter has those fuses directly on it I think. Anyway, it is a simple matter to troubleshoot this system. I have attached information regarding my converter and also how you can troubleshoot it.

Get a voltmeter and follow the converter troubleshooting capture I attached. I had to follow this procedure to diagnose a failed converter in my 2017 Greyhawk and it worked just fine.

Basically the test has you disconnect the positive output wire from the converter. This takes everything in your coach out of the circuit including the battery. Then you simply measure the converter output. You probably will have to replace the reverse polarity fuses as the test states.

Assuming the converter is able to produce output with no load on it, the next step would be to take the battery out of the equation. I would disconnect shore power, reconnect the positive wire at the converter, and then disconnect the cable connected to the positive terminal of the battery. Don't let it touch anything metal while it is dangling.

With the lead off the battery, connect your voltmeter from the positive battery cable to the negative terminal of the battery and apply shore power. What you are doing in this test is leaving the battery out of the equation. That way if the battery is bad or connected backwards, you will be able to tell if there is good voltage on the cable coming from the converter.

If there is good voltage on the cable, make note of what terminal the cable is connected to on the battery. If by chance the the voltmeter shows a negative voltage, this means the wire you just disconnected is the ground wire and not the positive one meaning the cables are connected to the battery backwards.

When the positive lead of the voltmeter is connected to the positive cable connected to the battery, the meter will indicate a positive voltage. If backwards, it will indicate a negative voltage by adding a dashed line before the number display.

Lastly, a totally dead battery when connected to your converter may prevent the converter from producing any output. I had this happen on my truck when I let the battery sit for months. The battery was so low, the battery charger sensed it and was not able to bring it back.

I hope this is not too confusing. This stuff is very easy for me as I have been an electronic tech for over 45 years and troubleshooting is second nature for me.

[Tone4181]

Thanks JimD will check it out this weekend.

[RedHorse1]

The reverse polarity fuses blowing strongly suggest the batt is hooked up backwards. If you haven’t changed anything perhaps someone else did in your absence, like bored kids. I hooked mine up backwards and it blew the rev. Pol. Fuses and fuses in my thermostats (digital) and radio. Real PITA to get sorted out.
“Oh crap, no DC. (searching) Fuses blown, oh crap, hooked batt backwards. NP, got spares. New fuses, all is good, time for a be... oh crap, the ACs won’t start. (searching). Oh crap, thermostats have fuses and both are fried. Oh crap, no spares, trip to the big box. Ahhh, AC working, DW happy, time for a be... oh crap, the radio is dark. (searching) Hmmm, radio fuse in the panel is good, (searching) oh crap, there’s another fuse behind the radio. Oh crap, no spare, nother trip to the big box.”
Short version, took a long time to get the first beer.

[ALJO]

75% of issues with RV's what comes through our service department are operator errors. Which means read manuals and learn all aspects of your RV. Learn the basics of electrical, plumbing etc. Why pay $$ an hour for simple things you can learn yourself.

[Tone4181]

Hello everyone just got back from my trailer . Figured out what the no power issue was the battery and not the converter. I have never heard of a battery reversing its polarity. The battery was dead , I put a charger on it and the polarity light would not light . Hooked it up anyway double and triple checking pos and neg is correct and charger would shut itself off. I removed the old battery and put a new one in making sure polarity was correct, the fuses stopped blowing and the converter was charging again .Everything back to normal. Thanks everyone for your help and input .

[Iraqvet05]

We had a John Deere commercial riding mower at work that had an issue with the alternator. That problem caused the battery to reverse polarity...the dealer says it happens but very infrequently.

I’d check your DC voltages on occasion and make sure the converter didn’t cause the battery issue.