Dometic 12v refrigerator

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olly72

Well-known member
Joined
Mar 11, 2009
Posts
113
Location
Pembroke Pines, Fl
Hi all this is my situation. Had to replace my 16 year old refrigerator right before leaving for 5 months. Put in a Dometic 12v DMC4101. Ran good for a month. Then discovered one of the deep cell 12v batteries had a low water in one of it's cells, filled it. The next day battery boiled over. Replaced both deep cell batteries. My mistake thought the converter was still good but it wasn't. Refrigerator caused new batteries to go done to 11.4v and refrigerator quit working. Used a battery charger and batteries did come back to life. They charged up to 13v. Used a load tester on the new batteries and they tested good. As long as I kept charger on the refrigerator would run. Bought a new converter, progressive 9200 model with four stages boost, normal, storage, and desulification. Installed new converter and it shows 14.2 at it's positive and negative posts. Now the refrigerator comes on for a minute and shuts off not keeping a cool enough temperature. The refrigerator is acting as though the batteries are not producing enough voltage. Tested the batteries again and they tested good. Any suggestions will be appreciated.
 
According to what I found that refer draws 15 Amps. They don't say if that is the maximum load when the compressor first starts or its run rate. To me that seems like a pretty hefty load for a pair of 12V batteries. In the specs it shows "Greater than or equal to 15Amps".

I just installed a dual compressor cooling unit from JC Refrigeration in my Norcold. When both compressors start at the same time it draws about 12Amps. That's enough to make the LED light in the refer flicker. It drops down to 3Amps once they get up to speed, usually in less than a second. I have 4 6V batteries rated at over 400AH.

I'm thinking you might need more batteries and probably a more powerful converter/charger.
 
I think you killed your batteries regardless of what your load tester indicated. Once the voltage got to 11.4V the damage was done. When a plate is exposed (low water) there's a good chance that plate will never reach 100% charge.

Premium (as in $$$$) batteries like Rolls or Surrette (or Lifeline AGM) might have a better chance of survival when abused.
 
Measure voltage AT THE REFRIGERATOR.
note batteries should read 13.6 after several hours plugged in with the 9200 (Give or take a tenth of a volt or two) Float voltage.

Poor connections between Fridge and power supply will result in reduced voltage.

Also measure CURRENT to the firdge when it first comes on (well a few seconds give it time to activate heat element) My Crafstman Clampon Meter does DC as well as AC. amps via the clamp.
 
Thanks for the good information. IWith the refrigerator tuned off for 24 hours it let the converter get the batteries up to 13.2v. Turned the refrigerator on and it is now continuing to run. I agree with all the information you all gave and will make those adjustments to be sure the unit continues to run. Thanks again.
 
With the refrigerator running, measure the voltage at the refrigerator and at the batteries. Compare them to see how much voltage is being lost along the wires feeding the refrigerator. There's a good chance the 12 volt wires feeding the refrigerator only deliver adequate voltage under the relatively low power needed by the circuit board on the original propane/AC powered refrigerator, not at the higher currents used by the compressor in a 12 volt refrigerator.

If you're losing voltage along the wires as the batteries fade the refrigerator will shut down from low voltage much sooner than it would if it was getting the full battery voltage.
 
One thing you almost certainly need to do is run much heavier wiring from the battery bank to the refrigerator, with appropriate fusing etc.
 
....note batteries should read 13.6 after several hours plugged in with the 9200 (Give or take a tenth of a volt or two) Float voltage.
.....
Determining state of charge in a traditional flooded cell battery is done by measuring specific gravity. If using voltage to determine SOC, the battery must be disconnected and at rest (no load) for 24 hours.
 
I think Lou is on the right track, if the OP connected up a compressor fridge to the 12V supply line that originally powered an absorption fridge, there is likely a lot of voltage drop at the refrigerator. Compound that with the startup and running draw of a compressor fridge, any weakness in the house battery is going to be amplified. No mention of the size or type of "deep cell" batteries installed, that would be useful information in determining run time but even a couple of new group 24 marine batteries would be up to running this fridge for the better part of a day. My bet's on wiring voltage drop.

Mark B.
Albuquerque, NM
 

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