Dometic fridge voltage polarity question

[VanTalk00]

I'm not quite sure what you mean, but yes, the next step is to further investigate the plug and contacts thoroughly.  My voltmeter probes had no difficulty with the plug but I'll look more closely now at both the male and female plug parts.

 

[bullfrog]

Does the male plug have a knurled collar on the center stab pin, there is usually a glass fuse held by a spring that can be accessed by unscrewing the collar, if you don't have 12 volts between the center pin and the outside prongs usually the fuse is blown. By hard wiring you do mean you did away with this troublesome plug right? Did you cut the power side wires with the power still on and maybe cause a short with the cutters blowing a fuse? In other words are you sure you have a good 12 volt source and ground?

 

[VanTalk00]

Looking at the photo attached to the first post in this thread, you can see there is 12 volts at the plug prong.  That means no fuse was blown upstream.  There is no center pin.

 

[VanTalk00]

Problem is solved. Fridge is working.

There was nothing wrong with the fridge or the circuit.  I had assembled the bed, which is over the fuse box.  I assumed that because I saw 12.59 volts at the plug that it was fused all the way to the battery.  Not so.  The short answer is that there was no fuse inserted in the fuse box for the fridge.  Pop in a fuse, and all itswell.

So why did I read 12.59 volts on an open circuit at the fridge plug?  Because, in spite of the lack of a fuse, it was not an open circuit. 

Here is a link to my 12 v distribution bus.  Apparently, there is a high impedance resistor across the open fuse contacts.  When there is no fuse inserted but a circuit is connected on the other side, a little red light illuminates telling you the fuse is blown.  When I inserted the fuse, the voltage jumped to 14.2v, the normal fully charged battery voltage.

At this point, the fridge starts up fine and immediately goes to 14 degrees F.

Lesson learned for all.  

Thanks for all your comments and suggestions.

Jim

 

[user 423]

^
Very interesting. Glad you got it going.

My next question was going to be how much of a voltage drop you had along the lengthened and spliced cord.