Dometic PLB40 Battery Pack Provides My 12V Power

The Dometic PLB40 battery pack has been in my gear since February of 2020.  So, a little over a year and a half.  It has solved a couple of power management problems for me.  1) Power my ARB fridge at all times without relying on the Jeep being running.  2) Provided extra USB device charging overnight or any time the Jeep is not running.

Unfortunately, it stopped charging from the rear 12VDC outlet in the back of the Jeep.  I’ve checked all the fuses in the fuse box and they’re okay.  The 12VDC outlets on the center console and in the rear cargo area may have some loose wires.  Sometimes they do not have power but if I twist or wiggle the connector they come back on.  That’s a separate issue that I’ll address later.  But the bottom line is I was unable to charge using the 12VDC regardless of the outlet I used; rear cargo, center console, dash.

I found a 3AG 10A glass fuse in the 12VDC plug.  If you unscrew the tip of the plug the fuse can be found inserted into the metal plug cap.  Inside the glass cylinder of the fuse I could see a number of brown spots and it seemed a bit yellowed.  That appearance is typical when a fuse is blown.  It’s the debris from where the element overheats and blows.  Sometimes the element blows inside the metal end cap and you can’t see it.  So, the element may LOOK intact, but it’s not.  I confirmed with a continuity check using my meter.  No continuity.  Bad fuse.

I couldn’t find this fuse in the Dometic documentation.  Due to the potential power use with this battery pack and the possibility of bouncing around in the Jeep causing sudden intermittent connection I suspect a Slow blow fuse is the better choice.  To err on the side of caution I went with the Fast Blow until I know for sure what it’s supposed to be.  I’ve sent Dometic a question about if this should be a fast or slow blow fuse.  If I hear back, I’ll update this info.

For now, it seems like it’s all working as it should be now.  But I’m going to continue to carry the AC charging cable.  I can always plug it into the inverter to charge it while driving during the day.  I’ll also be carrying some extra fuses from now on.  The ‘kit’ just got a little larger.



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