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Old 06-16-2024, 08:22 PM   #1
kayakcrazy11
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2019 3811ms No Power

I hope you guys like mysteries with twists and turns.

My parents have a 3811ms at the lake and my wife and I went up to use it for the weekend and we had nothing but problems.

I got the slides open and my wife noticed the fridge had no power, but it was cold. The freezer still had ice cubes in it (a sign it never got warm enough for them to lose their shape) So we assume that we tripped a fuse or breaker when we opened the slides.

I trouble shot everything the best I could, and came up short. I found a plug that was plugged into the Magnum inverter, plugged it into an outlet in the cargo hold and the fridge came back on. We still had many outlets (Tv, recliner, coffee pot) not working, but it was good enough for us.

The next morning we wake up and the entire camper is off except for the outlet in the island. The display panel is strobing white. I put a voltmeter on the batteries, and they said 3v. Obviously dead. We are on 50 amp power, and both legs are good. We have 110v in the island and cargo hold. All breakers were good ( I reset them all just in case) and no fuses were popped. The switch off the batteries is set to ON.

I did more digging, and I found the black wire that feeds the magnum inverter was not connected to the batteries. (My dad replaced the batteries last month and must have missed it?)

----------------------

I'm guessing the black wire needs to be connected for the fridge to work once I plug that back in, but I don't think that's the entire problem is it? HOW did the fridge work without that black wire plugged in while we were gone? Does it sound like the power converter went bad ? Should all this stuff work while on 50amp power, or are they all dependent on the batteries being charged to 12v as well ?

We are going back up next weekend with some tools, I know 110v and 12v systems well, but not this camper as it's my folks. Looking for some advice since we don't have internet out there.

Thank you all!
 
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Old 06-17-2024, 03:36 AM   #2
RMcNeal
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First, make sure the red key in the convenience center is turned such that it cannot be removed. That is the battery disconnect. If it can be removed, the batteries won't charge from the converter. Another possibility is that the battery was hooked up backwards (even momentarily) causing the reverse polarity fuses to blow. They are in the converter panel. They may be preventing the batteries charging.

For the AC side, you should have 2-50 amp breakers, one for each leg of the service. Make sure you have 120vac on each leg. If not, back up to the cord and check incoming voltage on each leg. You may need to trace from post, to cord, to panel, etc.
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Old 06-17-2024, 08:47 AM   #3
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Yes the inverter must be on for the fridge to work on 120 volt.
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Old 06-17-2024, 10:50 AM   #4
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Take a multimeter with you
Here's a diagram of how small inverters are typically wired for residential fridge use on batteries.
If you are plugged into shore power and do not have 120vac in all your receptacles, you may have an ATS (auto Transfer switch) problem, if your rig is wired for one (generator prep package).
The ATS is usually located behind the basement wall.
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Old 06-17-2024, 01:01 PM   #5
kayakcrazy11
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Thank you all. Great information so far.


Quote:
Originally Posted by Daryles View Post
Take a multimeter with you
Here's a diagram of how small inverters are typically wired for residential fridge use on batteries.
If you are plugged into shore power and do not have 120vac in all your receptacles, you may have an ATS (auto Transfer switch) problem, if your rig is wired for one (generator prep package).
The ATS is usually located behind the basement wall.
So I'm pretty sure it's the converter, and I have one on order to bring back up with me this weekend.... But now you got me wondering if it's the transfer switch.

Is there any way to know which one without having the camper in front of me based on my issues? I spoke to Keystone today and they said they believe it's the converter as nothing is working and the batteries are also dead.

They said the fridge stayed cold because it uses 110v shore power to cool and the 12v is only for the lights and the controls.
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Old 06-17-2024, 04:09 PM   #6
Daryles
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You probably already know this but I'm going to say it anyway.
The CONVERTER take 120vac from shore power input and makes 12vdc to run the lights, furnace, most control boards (RV fridge, water heater, Level-Up, slides, AC units etc.)
The INVERTER takes 12vdc from the batteries and makes 120vac to run a very limited number of things (residential fridge is one, recliners, and a couple of receptacles).
The island and basement and outside receptacles should be on a GFIC Circuit.
IF some receptacles are working and others not, I would suspect you are missing one of your two 50A legs.

If so, I'm guessing the leg powering your CONVERTER is missing (batteries not charging).
If you confirm this, AND you can measure your voltage at the pedistal is good, AND you measure good voltage at the RV end of the piwer cable, I would definitely suspect an ATS problem. There was a bad batch of ATS a few years ago (2019 included). This affected rigs with generators OR a generator prep package.
Carl wrote the Perfect 12vdc troubleshooting flow chart:
https://www.montanaowners.com/forums...ad.php?t=86323
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Old 06-17-2024, 10:39 PM   #7
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Quote:
Originally Posted by Foldbak View Post
Yes the inverter must be on for the fridge to work on 120 volt.
Only if his inverter has the transfer switch built in. In my 2019, the transfer switch is external to the inverter, so it will work with shore power without the inverter turned on.
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Old 06-18-2024, 11:44 AM   #8
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I agree with Daryle. Since you are also having issues with the 120 vac power I would thoroughly check that out and get it working before changing out the converter.

Start at the 50 amp breaker in your trailer load center. There should be 120 vac on both legs of that breaker. If not then the problem is upstream of your breaker panel. That could be a problem with your transfer switch (if you have one), a power cord problem, a problem at the trailer connector where the power cord plugs in, ….

If you have 120 vac on both legs of the trailer 50 amp breaker then check for 120 vac at all your sub breakers. They should all measure 120 vac.

If they all have 120 vac then check for 120 vac to your converter. If it has 120 vac input but no 13+ vdc output then there is a problem there. Could be a bad converter. But as Robert mentioned earlier the reverse polarity fuses could be blown if the battery was connected wrong. But that is a simple matter of replacing two fuses (after you verify the battery is connected properly).

If you have even a fair cell signal then you should still be able to access the forum thru your phone browser.
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Old 06-20-2024, 11:00 PM   #9
kayakcrazy11
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Quote:
Originally Posted by BB_TX View Post
I agree with Daryle. Since you are also having issues with the 120 vac power I would thoroughly check that out and get it working before changing out the converter.

Start at the 50 amp breaker in your trailer load center. There should be 120 vac on both legs of that breaker. If not then the problem is upstream of your breaker panel. That could be a problem with your transfer switch (if you have one), a power cord problem, a problem at the trailer connector where the power cord plugs in, ….

If you have 120 vac on both legs of the trailer 50 amp breaker then check for 120 vac at all your sub breakers. They should all measure 120 vac.

If they all have 120 vac then check for 120 vac to your converter. If it has 120 vac input but no 13+ vdc output then there is a problem there. Could be a bad converter. But as Robert mentioned earlier the reverse polarity fuses could be blown if the battery was connected wrong. But that is a simple matter of replacing two fuses (after you verify the battery is connected properly).

If you have even a fair cell signal then you should still be able to access the forum thru your phone browser.
Update. My phone is slowly loading but I'm going to try. I'm here at the camper. I have 220 to the 50amp drum that the shore power spools onto. But I only have 110v at the 50amp breaker. I lost one leg somewhere. Any advice? Ty!
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Old 06-20-2024, 11:27 PM   #10
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Quote:
Originally Posted by Daryles View Post
You probably already know this but I'm going to say it anyway.
The CONVERTER take 120vac from shore power input and makes 12vdc to run the lights, furnace, most control boards (RV fridge, water heater, Level-Up, slides, AC units etc.)
The INVERTER takes 12vdc from the batteries and makes 120vac to run a very limited number of things (residential fridge is one, recliners, and a couple of receptacles).
The island and basement and outside receptacles should be on a GFIC Circuit.
IF some receptacles are working and others not, I would suspect you are missing one of your two 50A legs.

If so, I'm guessing the leg powering your CONVERTER is missing (batteries not charging).
If you confirm this, AND you can measure your voltage at the pedistal is good, AND you measure good voltage at the RV end of the piwer cable, I would definitely suspect an ATS problem. There was a bad batch of ATS a few years ago (2019 included). This affected rigs with generators OR a generator prep package.
Carl wrote the Perfect 12vdc troubleshooting flow chart:
https://www.montanaowners.com/forums...ad.php?t=86323
Ok you are correct. Sorry for the double response here but yes I lost a leg on the converter side. Comes into the trailer fine but not at the panel. How would I test the ats and do you know where that's located? I can do that in the morning
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Old 06-21-2024, 06:04 AM   #11
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Quote:
Originally Posted by kayakcrazy11 View Post
Ok you are correct. Sorry for the double response here but yes I lost a leg on the converter side. Comes into the trailer fine but not at the panel. How would I test the ats and do you know where that's located? I can do that in the morning
IF, that drum is a Retractable 50A power cord reel that retracts into the rig, I have read of where the contactors can go bad on the drum.
Repair of the electrical contactors in the drum is not for the feint of heart.
Maybe with power DISCONNECTED, ohm out the internal cable from the power distribution panel to the input side of the reel.
IF you have an ATS it should be behind the basement wall on the passenger side. You can test for power here by removing the cover.

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Old 06-21-2024, 08:22 AM   #12
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Last night the red wire (left panel) was 110v and the right was dead. This morning I woke up to everything off. And now the opposite side is hot. The black wire (right) is hot instead.


I Put a battery charger on the batteries, reset the shore power and now I’m back to where I was yesterday. The red side is hot again.


I found a MAGNUM DIMENSIONS Model: CSW-TS15 transfer switch in the basement.
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Old 06-21-2024, 08:50 AM   #13
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I believe the Magnum Invert/transfer switch powers the residential fridge. See post #4 above (similar setup).
You are looking for a silver box about 12" x 8" x 4" with big power cables going in and out.
This is mine when I installed it behind the CB panel. I believe factory installed ones are behind the basement wall.
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Old 06-21-2024, 08:57 AM   #14
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Quote:
Originally Posted by kayakcrazy11 View Post
Last night the red wire (left panel) was 110v and the right was dead. This morning I woke up to everything off. And now the opposite side is hot. The black wire (right) is hot instead.

I'm guessing you are talking about the shore input wires coming into the power distribution (CB) panel.
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