Norcold Refrigerator Power Mystery

[TimD]

Perhaps someone here can help this retired engineer (BSEE / MSCS, not bragging) understand what's the heck is going on here.

I'm in the final stages of wiring up a Beech Lane 'fridge aux fan.  My plan, based on a suggestion by @Ronbrink in this post , is to splice the fan power into the heavy-gauge red & yellow power cables connecting to the rear of the 'fridge.  Soldering to the yellow conductor (ground) went fine. 

The red (+12V), however, is sitting at 12.09 V after I've pulled the 20 A Refrigerator fuse (#1).  With the fuse in place the voltage rises to 13+ V, which is what the solar charger is putting out at the moment.  I have not yet disconnected the batteries...

To be clear the 10 ga. red & yellow wires come up through the floor of the 'fridge compartment and normally connect via spade lugs to the black control box on the back of the 'fridge.  Are these not the DC power cables to the 'fridge?  I don't think they lead to a motor start capacitor... Seems like there's some path to the batteries, but I don't understand why that is, and why it isn't interrupted when I pull the fuse!

Thanks in advance...

Tim

Edited Friday at 07:32 PM by TimD

[Ronbrink]

43 minutes ago, TimD said:

Are these not the DC power cables to the 'fridge?

Yes, the same lead wires I spliced into to create two additional sets of power leads for the Beech Lane control panel and fans. 

 

47 minutes ago, TimD said:

I don't understand why that is, and why it isn't interrupted when I pull the fuse!

I never put that much thought into it, perhaps someone will provide a rational. 

[CRM]

1 hour ago, TimD said:

The red (+12V), however, is sitting at 12.09 V after I've pulled the 20 A Refrigerator fuse (#1).  With the fuse in place the voltage rises to 13+ V, which is what the solar charger is putting out at the moment.  I have not yet disconnected the batteries...

 

Not sure it would cause this or not, but is it possible you have one of those "fridge defenders" installed? Maybe it's holding some voltage if so? Have you tried putting a test light between the connectors to bleed off any voltage? 

Edit- better yet, maybe hook your fans to them to see if they bleed it off? 

Edited Friday at 08:50 PM by CRM

[Snackchaser]

4 hours ago, TimD said:

I don't understand why that is, and why it isn't interrupted when I pull the fuse!

Tim,

The "blown fuse" LED indicators in the Oliver's dc panel will create a voltage even with the fuse pulled.  This is mere milliamps, not a hazard, but a multi meter will pick it up. 

Cheers!  Geoff

[TimD]

11 minutes ago, Snackchaser said:

Tim,

The "blown fuse" LED indicators in the Oliver's dc panel will create a voltage even with the fuse pulled.  This is mere milliamps, not a hazard, but a multi meter will pick it up. 

Cheers!  Geoff

Hey Geoff, yes, that's what I suspected, and the notion it was coming from the panel was confirmed when I pulled the cable off the back of the panel and the V went to zero.

Oddly the LED did not illuminate when I removed the fuse, unlike with the other fuses I tried.

Thanks everyone, this forum rocks!

Tim