2022 Tab 320 BD Electrical Conundrum

BandB

I couldn't find the answer in a previous discussion, so I'm turning to all of you once again.
Everything works fine when we're plugged into shore power, but nothing works when running only on battery. 
My husband has checked all the fuses on the battery and inside the Tab. Our lead acid battery is fully charged.
We have a Victron shunt, and that's all doing fine per the app. We do have the battery knob in the propane tank box turned to green.
The factory-installed Victron unit for the solar panel under the driver's side bench hasn't been working all summer, meaning it's not detectable by the app.
Any thoughts? We're heading out camping in five days and would like to get this sorted out.
Thank you so much!

Yoshi_TAB

Hi,

The below sketch shows how it's wired if your unfamiliar.  The 12V power from your battery goes thorugh a 30 amp fuse, through the ON/OFF switch , to a junction box located under the trailer frame.  From the junction box, the wire goes into your TAB directly to the WFCO power center.  The WFCO power center distributes the 12V power to the fuse block on the right side  of the WFCO to the individual 12V circuits for each 12V appliance in your TAB.  The solar is a seperate circuit and I'd put that to the side for now until you sort out the 12V issue.

I would suggest:

1.  Confirm with a voltmeter (hopefully you have one)  your battery is fully charged.  You should have 12.6V or there about.

2.  Confirm all your connections on your battery are tight.

3.  Confirm the battery fuse (in the tub)  is not burned out.  Sometimes they are hard to see if burned out.  I would check the fuse with a meter using the continuity setting. I would check the power across the fuse to confirm you have 12V.  If your not sure how to do this...please ask.  This will check everything up to the fuse. 

 It's hard to check anything else until inside the TAB at the WFCO.  You can check the junction box if you suspect a bad wire connection there.  It is the #6 stud.  You take cover off.  But I'd hold off on that for now.

4.  Confirm the bottom two fuses in the WFCO are good by checking continuity.  

5.  Confirm you have 12V in the WFCO.  If you open the WFCO cover and remove one of the fuses and use a meter to check for 12V across the open fuse.  You should have 12V.

Hope this helps as a start....Ask if anything is unclear.

fwunder

When you say "nothing works" do mean lights, stereo and fan? The battery power is distributed at your WFCO converter. You have a series of 12 volt fuses. If nothing is working on battery power you need to check voltage @ converter. You also need to check main 12 volt circuit breaker. Not sure where that is on 320. An inexpensive 12 volt meter you can get at any hardware store will help you solve the problem. It should be simple.

MuttonChops

How were the Power Center Fuses 'checked'?
    Best method (with all power off) is to remove and check with an ohm meter.

What you describe sounds like a possible Reverse Battery or Solar Panel wiring error.

Suggest you:
 = a =  Confirm in-line fuse at battery are on wires connected to the battery Positive Terminal
 = b =  Confirm the Power Center two bottom fuses 30A & 40A are good.
             These two connect to battery and detect battery is installed correctly.
 = c =  If 'a' and 'b' are correct/okay, consider removing the Solar Controller Battery connections

SLJ

There is a reverse polarity battery fuse in the WFCO controller. On my 2021 320S it's the bottom fuse (#7). Most likely a 40 amp fuse. Check that also. If the battery was hooked up backwards even for a second that could be blown.

BandB

@Yoshi_TAB, @fwunder, @MuttonChops, you guys are amazing. Thank you so much for your responses. I've printed them out and given them to my husband. He does own a volt meter. Hopefully, with your insights, he can figure this out. 

BandB

@SLJ, thanks. I'll have him check that, too. (You're amazing, too!) 

bjn2

I had a "nothing works on battery power" issue of my own making. After installing a Victron Shunt near my Dr. Prepare PowerMax battery, I installed what I thought was a two-post bus bar to even out the wiring on the positive side of the battery. I eventually figured out that I had installed a terminal block with discreet (not electrically connected) terminal posts. That meant the battery was completely isolated from the trailer's wiring. Oddly, with the battery disconnected, we somehow got a little 12v power when I disconnected shore power. We got enough DC power to run the fan or lights for a brief time. I can't make sense of that unless our WFCO converter has a capacitor. After running the fan briefly, the converter would start cycling a relay and flashing status lights that went from green to blue light to off. The cycling would get faster and faster until it eventually quit.

I found my error using a multimeter to check connections starting at the battery.

BandB

We now have power with battery.  After checking all connections, fuses, and the junction box under the frame, something that had jiggled loose must have gotten reconnected. My husband never found a particular problem. Thank you all for your input! 

Yoshi_TAB

"something that had jiggled loose must have gotten reconnected"...Engineering at it's best :   Glad it worked out.  If nothing else, I'm sure you learned a lot which is always helpful.

bjn2

BandB said:

...something that had jiggled loose must have gotten reconnected. 

Electrical connections rarely, if ever, reconnect. You might get intermittent issues if there's something loose. Or perhaps it was just a mistake in checking the position of the battery cut-off switch. I'm really glad to have this forum since I'm still climbing the learning curve with our new trailer.