Battery Reverse polarity problem 19xud

[Alaskachef]

Hello my TT is a 19 XUD and my battery is showing a full 12.46 charge but every time I disconnect from shore power or from my generator. I am not getting any DC power at all. I have checked the fuses and they are good what else could be the problem.

[tnchuck100]

There could be 3 fused involved here. 1 inline at the battery, 2 in the converter (1 main and 1 reverse polarity).

Have you checked those?

Next I would look for a bad connection from the battery negative to the frame.

[RoyBraddy]

Certainly sounds like the battery may have been connected in REVERSE POLARITY or you have a battery disconnect switch engaged or bad connections between the 12VDC Power Distribution Panel and the Battery terminals...

The BATTERY TERMINALS are easy to determine. I always find the WORD 'NEG' or the symbol '-' that is stamped on the 12V BATTERY CASE and make sure this is the cable that goes to FRAME GROUND near the battery..

My Interstate 12V SRM-24 Batteries has two very large + and - symbols next to the battery terminals

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If this was ever installed wrong or or even just sparked in the wrong position it will immediately blow a fuse that is installed very close the battery as well as two fuses labeled REVERSE POLARITY that are installed sometimes on your 12VDC Distribution Panel. Sometimes these two fuses are installed on the on-board CONVERTER/CHARGER unit itself. You have to correct the battery terminals first then replace the blown fuses. Otherwise they will just blow again as soon as you plug new ones in...

My REVERSE POLARITY fuses are installed like shown on this WFCO 8900 series Power Distribrution Panel which are the two RED fuses rated at 40A each. These two off-set fuses could be either 30A or 40A rated depending on the DC OUTPUT of your on-board converter/charger unit. I am using the PD9260C Converter/charger 60A DC output unit.

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You want to be be able to read the working BATTERY DC VOLTAGE at the 12VDC Distribution Panel at the + and - connection point.

When things are normal you should be able to read 12.6-7 VDC at the Battery Terminals if fully charged without shore power turned on. Then reading at the same battery terminals you should see an increase to around 13.6VDC or higher depending on the on-board converter/charger charging mode when you plug into shore power or generator.

On my 12VDC Power Distribution setup the top lug and the bottom lug are the two battery cable connection point to my setup. This is where you want to see the 12VDC VOLTAGE coming from your working battery bank connections.

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Of course different model have different connection point but wanted to show what mine looked like to give you an idea where to look for your setup...
We make a conscious habit of checking these points during our first walk-around every morning...

I certainly don't want to get caught without my working battery for something I did or didn't do...

Hopefully your working battery was connected to your BREAK-WAY Cable system to operate your electric brakes in the event the trailer became disconnected during your trip to your camp site. This is a DOT SAFETY requirement when on towing public roads. No one likes to hear about a run-away trailer...

We are always aware of our working battery bank charge status. Best to catch these things at home before hitting the road going somewhere...

Roy Ken

[Alaskachef]

I'm attaching pictures of my fuse panel. Where would I test for the Dc power. I assume the black an white wires at the top which is on the left In this picture but I don't know about these things. Thanks for all your help

[RoyBraddy]

Could you pass along your converter/charger model number where this fuse panel is located in... That 40Amp fuse is suspect being your REVERSE POLARITY fuse. There really should be two of them however...

Maybe pull both of those 30A and 40A fuses and see if they are blown ...

If i had a model number I could look up a better photo perhaps for your wiring. White is ground and Balck is POSITIVE in this case... I was expecting to see terminal lugs how ever...

Did you locate the FUSE just 12-inches away from the battery terminals... It should be a 30 or 40AMP in-line fuse as well. That needs to be checked...

Hard to troubleshoot from afar - All your items are different than all of my items haha...

Without shore power or generator ON you should read your 12.48VDC Battery Voltage at those WHITE and BLACK larger cables you show in your photo...

Have you messed with the battery terminals recently - maybe you took them off and they didn't go back on the right terminals... The WHITE cable should go to the '-' terminal connection and the Black should go to the + terminal connection.... The white '-' battery terminal should also go to FRAME GROUND real close to the battery.

pass along your converter/charger model number... Also what year is your 19XUD trailer... That may help as well...

Roy Ken

[Alaskachef]

It is a 2016 19xud and the converter is a WFCO model- WF-8735-P. I am not seeing an inline fuse at all. I have followed the wires all the way into the trailer and as far as I can inside. Along the trailer frame the wires are inside a flexible hose that is taped shut. I have followed them in this hose but have not cut the tape and opened it all the way up. I will include a picture of the wires from the battery. Thank you, I know it's difficult helping from afar but every little bit of advice really helps.

[Alaskachef]

Here's another view

[RoyBraddy]

Sorry i got busy here - Just now getting back to reading the mail haha...

The WF-8735P is a pretty simplified Power Distribution Panel and 35AMP Converter.Charger board. I have never seen one of these - am very familiar with the WF-8900 series units which I have....

That 40AMP ATC FUSE definitely goes to your battery terminal... You need to pull it out and inspect it. You will be able to see if the fuse has been blown looking at the ATC fuse.

I don't see a IN-LINE FUSE in this install using this converter/charger unit like my WF8900 series does it.

This is a close schematic of the unit...


This is not your exact unit but shows the very bottom FUSE being your REVERSE POLARITY fuse.

The +BAT connection from the unit goes straight to your POSITIVE BATTERY Terminal from your 40AMP ATC.

I saw in another diagram on-line the 30A ATC FUSE went to the SLIDE motor...

Using a MULTIMETER you should be able to read the 12.4VDC you are reading at the battery terminals here at this FUSE. One lead on the FUSE and the other fuse on - 12VDC connection or frame ground ground...

This should not be hard to trace down. If you have the 12.4VDC here coming from the Battery Terminals then the only thing in line now is the FUSE. If the 40A FUSE is good then both the battery connection cable and the +13,6VDC OUTPUT of the 8735 will both be feeding the above fuses which one of those is feeding your ceiling lights...

IS there another large black four blade plug in device on the very bottom... This may be the REVERSE POLARITY device and the 40AMP fuse is doing what the IN-LINE we all have been discussing. The fuse slots in my drawing don't agree with your newr 2016 12V fuse panel

try to find all of this out and get back to me...

I also never heard back from saying you have physically seen the WHITE CABLE at the Battery terminals going to the frame ground close to the battery. This should be connected to the NEG '-' terminal of the battery. The '-' symbol should be printed on your battery case. If the negative '-' battery terminal of the battery does not go to the trailer frame ground then you have the battery hooked up backwards... Get back to me with this info as well...

The schematic shows your two battery cables only going to the battery and the frame ground is connected to converter/charger unit five position ground lug unit. Maybe this is what is throwing me off...

Roy Ken

[Alaskachef]

I have attached a video of my battery leads and where I believe the white wire is grounded to the trailer frame. I also have used jumper cables to try and troubleshoot by creating a ground to the trailer and see if that solves the problem. Creating another ground made no difference. I checked the fuses again and they all looked fine. While plugged into shore power if I remove the 30 amp fuse that is labeled " for battery and slide out used" the electric awning and slide will not work until I replace it so I know it's good. When I remove the 40 amp which says Reverse battery protection fuse underneath it, I lose all power until I replace it so I know that it is working. All other fuses are good and controlling the Dc power while conected to shore power as they should.

[Alaskachef]

Here is another view of the inside of my load center panel. I believe the yellow wire is the positive coming off the motherboard and going into the back of the reverse protection fuse. There is a white negative cable next to it idk where that is coming from or going to. I've called my dealership to try and get this problem looked at but they say it will take a while to get it in. I'm really thankful for all of your input. Im learning a lot about how all this stuff works. Unfortunately I'm a Chef and not an electrician.

[Twin Hauler]

Im having same issues. Can you help?

[Alaskachef]

My problem ended up being an in-line fuse that was located in a compartment Behind the storage cubbies under the front bed. Not easily accessible but the guy at the dealership was able to find it. He relocated it to the storage compartment under the bench seats for me in case I ever have to replace it again.

[Twin Hauler]

Originally Posted by Alaskachef

My problem ended up being an in-line fuse that was located in a compartment Behind the storage cubbies under the front bed. Not easily accessible but the guy at the dealership was able to find it. He relocated it to the storage compartment under the bench seats for me in case I ever have to replace it again.

ok. Lucky you. I found that fuse, and replaced and still nothing.

Im going to have to check all the grounding points.

[Twin Hauler]

I found out there is no ground from battery until after the converter, and the screw broke that was holding 2 grounded wires to the frame at the back of the camper. SO i sanded the frame bare, and put in a new self tapping screw and problem fixed!