3 way fridge 12V voltage level - SOLVED

webers3

Removed the 3 way fridge and wanted to use the 12v line that went to the 3 way fridge to power the new 12v  fridge but when I measured the voltage on the 12v line it shows 11.3v even though the battery voltage is at 12.7v. I measured the voltage at the battery and at one of the 12v outlets inside to verify the 12.7v. Any explanation why the voltage on the fridge line is low?

AnOldUR

Can't explain except to say that we removed our 3-way fridge in favor of a 12V slide-out chest and used the existing 12V line. With a rested battery, we get the same voltage there as at the battery (or any other place). Works great!

webers3

Thank you @AnOldUR, I am actually following your plan to replace the 3 way. This has me stumped. 

Denny16

You either have a small resistance short in that wire, or a bad splice/connection point.  Try disconnecting the wire from the power converter at the fuse connection, measure the voltage at the fuse load side, if it is 12.x VDC, then next, cut off the wire ends and re connect them, if still getting a voltage drop, trace the wire, there is an issue somewhere along the wire run.  

cheers

AnOldUR

To add to what @Denny16 said above, if your 2017 320S is the same as my 2020, the fuse is a 20amp at F4 location and the refrigerator is the only thing in that circuit.

webers3

@Denny16 so that wire runs straight from the fridge to the converter? @AnOldUR by F4 location you mean the auto style fuse?

AnOldUR

@webers3 ... I did not trace the wire, but when testing my battery draw I checked each circuit individually and didn't find anything else but the fridge on F4. That's also what I've read in different places. And yes, F4 is an auto style fuse.

(the 20amp fuse at F4 is in upside-down, but this picture shows its location)

webers3

@AnOldUR Thanks again, it’s confusing because one diagram I am looking at for 2016 320 has fridge on F2 but will verify and test when I go back to it. 

webers3

Well, that's embarrassing, it was the fuse. It didn't occur to me to check it to begin with because there was voltage, although lower, on that line. So I don't understand why there was voltage on the fridge line with the fuse out.

Dutch061

Voltage was likely due to feedback on the ground circuit.

Brad

webers3

@Dutch061 Is that bad or ok?

Dutch061

I'm sure it is fine, sorry to create the concern.

Brad

AnOldUR

Glad to hear you worked it out. Out of curiosity, which slot was your fridge fuse in?

webers3

@AnOldUR it was in #1. Now I need some cabinet making skills so I can do what you did

ckjs

@webers3
That phantom 11.3v was probably due to the tiny current which powers the “red fuse is blown” LED in the WFCO. The LED is usually shorted out by the fuse, but when that’s blown a trickle current runs through the light and then to the fridge or other load. 

AnOldUR

webers3 said:

Now I need some cabinet making skills so I can do what you did

My cabinet making skills are all but nonexistent. I faked it by repurposing the wood from when I pulled out some of the rear cabinetry. The face panel on my pullout is the lid for the rear storage compartment cut down to fit.

Viajero

Glad it worked out for you. What model did you replace it with?

webers3

@Viajero Replacing it with ICECO JP50, have used it for over a year and so far so good. Set the temp and forget it, unlike the 3 way