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Jeff7176 · 11-28-2021, 07:36 AM

I need some help. After a couple years of having a tattered up 7-way cord I decided to replace it. Rather than running it all the way into the trailer, I installed a junction box near the battery box and tied in a new cord.

After getting it installed I did a test and everything worked like it should. A few days later we headed to our next location, and at a rest area my wife noticed we have zero 12V power. No lights, no water pump, no fridge (running on Lp), and I noticed the propane detector light was off. Turned on the inverter and everything came to life.

When we got to our next campsite I started to try and hunt down the problem and then noticed the tongue jack wasn't working either.

I checked voltage at many places. I checked the use/store switch and solenoid...good. I checked the fuses in the use/store solenoid...good. I checked the 30a fuse for the tongue jack...good. I checked the batteries...good. There isn't much left that is obvious and before tearing anything else apart I thought it would be wise to ask for some help.

Any ideas?
Jeff
2018 International Serenity 25FBQ

fran&frank · 11-28-2021, 08:01 AM

A few more details would help. Are you sure your battery disconnect is turned on? Do you really mean the inverter, or do you mean the converter/charger? Do you have a a separate inverter and a converter/charger, or a inverter/charger?-- Frank

OutdoorIdaho · 11-28-2021, 08:04 AM

Am I understanding correctly that your 12V system is presently controlled by the state of your inverter?

Does the state of your use/store switch change anything? That is, do your lights stay on regardless of that switch position?

Assuming you are not connected to shore power, yes?

OutdoorIdaho · 11-28-2021, 08:13 AM

Quote:

Originally Posted by Jeff7176

...then noticed the tongue jack wasn't working either.

Huge clue here. The positive for the tongue jack is usually connected directly to your battery. If yours is connected that way then the problem is with grounding.

Are your negative battery cables both securely connected to the correct terminals?

ROBERT CROSS · 11-28-2021, 08:20 AM

"Inverter" or converter/charger?
Define 'tattered'. Any exposed wiring?

As Dad always told me...."What was the last thing you fixed."

Bob
🇺🇸

Jeff7176 · 11-28-2021, 08:24 AM

I have a magnum hybrid inverter/charger.

The 7-way was scraped up from dragging the ground once. You could see some of the internal insulation but not any bare strands of wire.

Jeff7176 · 11-28-2021, 08:28 AM

Quote:

Originally Posted by OutdoorIdaho

Am I understanding correctly that your 12V system is presently controlled by the state of your inverter?

Does the state of your use/store switch change anything? That is, do your lights stay on regardless of that switch position?

Assuming you are not connected to shore power, yes?

Yes...it works when the inverter is on or we are plugged into shore power.

The use/store switch will shut off lights/etc when set to store when on shore power or with the inverter on.

Jeff7176 · 11-28-2021, 08:38 AM

Quote:

Originally Posted by OutdoorIdaho

Huge clue here. The positive for the tongue jack is usually connected directly to your battery. If yours is connected that way then the problem is with grounding.

Are your negative battery cables both securely connected to the correct terminals?

Just checked again. All the battery connection are tight. Don't see any loose grounds but will continue to search.

ROBERT CROSS · 11-28-2021, 08:40 AM

Quote:

Originally Posted by Jeff7176

I have a magnum hybrid inverter/charger.

The 7-way was scraped up from dragging the ground once. You could see some of the internal insulation but not any bare strands of wire.

Ahh...as noted re-check all grounds.

Bob
🇺🇸

So it won't happen again (I now use a velcro strap instead of zip-ties)....

**richard5933** · 11-28-2021, 09:19 AM

Quote:

Originally Posted by ROBERT CROSS

"Inverter" or converter/charger?
Define 'tattered'. Any exposed wiring?

As Dad always told me...."What was the last thing you fixed."

Bob
🇺🇸

This ^^

If the problem only started after you replaced the power cord and installed the new junction block, my guess is that something was not connected properly in there.

Retrace your steps and see what you got wrong. Possibly you followed the color coding on the wires but the new wires are coded differently than the original.

Sounds to me that the main 12v lead to your fuse panel is not properly connected, but when you bring your inverter online it is somehow bypassing the problem.

telcoman · 11-28-2021, 09:20 AM

This may be normal. If the invertor is the type that automatically cuts in when the outsi e power is interupted, that is the way they work. They have an off, standby and active setting. They have to be in standby for your 12v to work. Mine has 3 leds red, yellow and green. The yellow one has to be on.

Camr · 11-28-2021, 10:40 AM

Wow. This one is a tough one. If the inverter is working fine, then the batteries are in good shape. They generally don’t work well with low voltage or poor cable connections. The jack issue points to what should be a simple issue as it’s connected directly to the battery. If it is getting a solid 12 volts, then the only issue other than the complete failure of the jack, would be the return current back to the battery ground terminal…. Which is the frame. Check to verify that the frame to battery ground is good. If the connection between negative post of the battery and frame is comprised, then the jack won’t work, and the entire 12 volt system won’t work.
Thy running a wire from the negative post of the battery to the frame.

**richard5933** · 11-28-2021, 11:44 AM

Quote:

Originally Posted by telcoman

This may be normal. If the invertor is the type that automatically cuts in when the outsi e power is interupted, that is the way they work. They have an off, standby and active setting. They have to be in standby for your 12v to work. Mine has 3 leds red, yellow and green. The yellow one has to be on.

Are you sure about this? The inverter is tied into the 120v circuits, but the only connection to the 12v system should be the the conductors which bring 12v to/from the inverter.

The house circuits, the jack, and the break-away brakes should have power through a separate feed from the 12v battery bank.

The 12v circuits should function regardless of the switch position on the inverter.

Jeff7176 · 11-28-2021, 12:31 PM

That's what I think but still have no luck. I tested the jack fuse and it had continuity but when I measured across the fuse to the Jack's input I get nothing. It's good without the fuse, so that could be a good start. Off to the fuse buying place

ITSNO60 · 11-28-2021, 12:42 PM

Quote:

Originally Posted by Jeff7176

That's what I think but still have no luck. I tested the jack fuse and it had continuity but when I measured across the fuse to the Jack's input I get nothing. It's good without the fuse, so that could be a good start. Off to the fuse buying place

You are not going to get any voltage measuring from the fuse to the jack because you are checking the same line just at different points. If you have continuity across the fuse it is good. You need to test for voltage between the jack side of the fuse and ground.

Jeff7176 · 11-28-2021, 01:09 PM

Checked continuity and it is good. Checked voltage from the battery side of the fuse holder to ground and get 13.7V. Checked from the jack side to ground and get nothing.

Jeff7176 · 11-28-2021, 01:25 PM

So I did get the jack to work. I can't seem to get continuity through the fuse hold so I pulled the fuse and put a drill bit in its place. And the jack works just fine. I obviously can't roll around with a drill bit in place of a fuse, but I know the jack is ok.

So step one complete. I'm not sure how many steps there will be or what I need to do with this new information, but it's progress.

Jeff7176 · 11-28-2021, 01:33 PM

Update of the.moment...the fuseholder seems to have lost the ability to hold a fuse and pass continuity so I'm gonna get one of those now.

Jeff7176 · 11-29-2021, 09:32 AM

New fuseholder installed and jack is operating fine.

Now on to the rest of the issue.

Jeff7176 · 11-29-2021, 11:25 AM

In case anyone is interested, the proem is resolved.

Our batteries are inside, under the bed and we have 12v posts in our battery box. There is a battery terminal fuse on the positive post and apparently it is bad. It wouldn't allow 12v to pass how it should (that is my best technical explanation)and when I replaced it, everything was good again.

Don't know how it failed (it's a 100a square block fuse) but it did. The tongue jack issue was just a happy coincidence.

After about 48 hours and $20, things are back to normal.

Thanks for the assistance.