Power issue when on battery

Tim L

Advanced Member
Joined
Jul 6, 2018
Posts
36
Location
Bunker Hill
Hello everyone, Need opinions.
My trailer is a 1997 Casita with a Magnatek converter which I believe to be original. Everything works great when plugged in. Problem is when running on batteries sometimes lights are very dim, fan barely runs, while other times everything works great. Battery is charged to 12.7 volts. I have checked as many connections as I have been able to get to including two different grounds to the frame, however I don't know if these ground connections are for the converter since they were just ground wires coming out o the belly of the trailer.

I suspect it is a grounding issue but don't know much about RV converters. I am assuming that when running on batteries alone the electrical converter has nothing to do with the process, or does it still come into use?

Thanks
Tim
 
Welcome, Tim
My (admittedly limited) understanding of trailer electrical systems is that an inverter changes DC to AC, and a converter changes AC to DC. This being the case, it sounds like your converter is working fine when plugged into shore (AC) power. If the system is not working when on DC (battery) the problem probably lies elsewhere than the converter.


I have now exhausted my trailer electrical knowledge!
 
Some converters have a relay that senses 120 VAC
The relay has a set of N/O & N/C contacts
When you are connected to shore power the 120V relay energizes closing the N/O contacts and supplies 12VDC from the converter to the trailer
When not connected to shore power the relay is deenergized and the battery supplies
12 VDC to the trailer through the N/C contacts
The N/C contacts often fail or make a high resistance contact causing low or no DC supply voltage to the trailer
I had to replace the relay in one of my previous trailers
 
Last edited:
Hello everyone, Need opinions.
My trailer is a 1997 Casita with a Magnatek converter which I believe to be original. Everything works great when plugged in. Problem is when running on batteries sometimes lights are very dim, fan barely runs, while other times everything works great. Battery is charged to 12.7 volts. I have checked as many connections as I have been able to get to including two different grounds to the frame, however I don't know if these ground connections are for the converter since they were just ground wires coming out o the belly of the trailer.

I suspect it is a grounding issue but don't know much about RV converters. I am assuming that when running on batteries alone the electrical converter has nothing to do with the process, or does it still come into use?

Thanks
Tim

Grounding is not the issue - the battery wiring is where you need to look.

You need to use a voltmeter to test this. They are inexpensive - here is one from Amazon for $11:
https://www.amazon.com/AstroAI-Digi...rds=voltmeter&qid=1563977641&s=gateway&sr=8-4

The battery wires for the Casita run from the battery compartment through a hole into the trailer to the converter. Make sure the battery terminals are clean and the wire is not damaged.

Then using a voltmeter, test the voltage at the battery connections on the 12v panel in the converter. The cover is removable - I would disconnect 120v power when doing this as it exposes the breakers as well. There are the two big lugs that will have the battery wires terminated on the 12v panel - make sure they are tight as I have found they will loosen over time.

Clean battery terminals and tight 12v wiring connections will more than likely fix your problem. The voltmeter will tell you where to look for the issue.
 
Magnatek converters were installed by many trailer manufacturers in the 90"s. They have a less than stellar reputation. I had one in my 94 Bigfoot. and when I removed it to replace it with a Progressive Dynamics unit I discovered that the vinyl flooring under the converter was scorched and burned from the unit overheating. I suggest you get the model # of the converter and do a google search of your particular units issues. Mine had a reputation of scorching the flooring on other trailers. The newer converters have much improved technology. Putting money into a 22+ year old converter with a not so good reputation would not be something I would personally consider.
 
When I replaced my Magnatek with a Progressive Dynamics, I used a model that allowed me to use the existing metal cover from Magnatek with the new converter. There were so many Magnatek converters being replaced that Progressive Dynamics built a unit designed as an easy replacement. I've sold the trailer and passed the paperwork along to the new owners, so I can't give you model numbers.
 
When I replaced my Magnatek with a Progressive Dynamics, I used a model that allowed me to use the existing metal cover from Magnatek with the new converter. There were so many Magnatek converters being replaced that Progressive Dynamics built a unit designed as an easy replacement. I've sold the trailer and passed the paperwork along to the new owners, so I can't give you model numbers.

If you are ever looking to do a converter/DC fuse board upgrade I suggest contacting Best Converter. They know their stuff.
Upgrade Kits for Magnetek/Parallax
 
Magnatek converters were installed by many trailer manufacturers in the 90"s. They have a less than stellar reputation. I had one in my 94 Bigfoot. and when I removed it to replace it with a Progressive Dynamics unit I discovered that the vinyl flooring under the converter was scorched and burned from the unit overheating. I suggest you get the model # of the converter and do a google search of your particular units issues. Mine had a reputation of scorching the flooring on other trailers. The newer converters have much improved technology. Putting money into a 22+ year old converter with a not so good reputation would not be something I would personally consider.

It is interesting about the scorched floor, because I don't think this unit has a cooling fan on it. I will remove it and see what's going on in there.

Thanks everyone, I will keep checking and report my findings.

On a side note, everything in this trailer is original, and still working.
 

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