A few electrical issues for your consideration

Hi everyone! We built the campervan (2021 Promaster) two summers ago and all in all it turned out very well. However recently some electrical issues have begun to rear their ugly head. Ive been working to troubleshoot but havent been able to resolve them yet. I will list the issues and am VERY appreciative of any thoughts/suggestions that you give.

  1. There is an issue with the battery monitor (Renogy 500a battery shunt and monitor). The displayed battery level will jump from say 50% to 100% full just after a few minutes of DC-DC charging (its a 600Ah LiPO4, so not possible). It has also displayed the level to be quite full, say 50%, but then the whole electrical system died, because the batteries were indeed fully discharged. This also has raised questions about whether all 3 methods of charging (shore, solar, and DC DC) are always working properly. In my mind, this could simply be a battery monitor error, OR it could be issues with the charging methods and/or problems with the battery health.

  2. The breaker for the DC-DC charger frequently trips even though it is a 90amp breaker and the DC DC charger charges at 60amps.

  3. And last but not least, just this past weekend I noticed that the plastic fuse holder for the 300amp fuse between the positive terminal of the battery and the Victron distributor had melted a little bit. Surely that cant be a good sign! I certainly cant think of a time when we would have created even close to a 300amp draw.

Or perhaps all of these things are related somehow?!

Any thoughts are very welcome. Thank you!


If you have fuse holders melting you have major issues that need to be addressed immediately. If things are melting you have an large current draw, short or malfunction. You have a huge risk of a fire. Who did the electric build? Wiring correct gauge?
Imo If you are not well versed with electrics I would recommend taking it to a certified electrical auto shop which is probably going to be hard to find.
Too many variables to troubleshoot on line.
For now I would turn the electrical system completely off and not park the truck in a garage of building or you could burn that down also.
If you are full time and sleeping in it I would buy a smoke detector and priority one to get it resolved.
Take some pix and post to see if its something obvious.



If you have solar, disconnect it first, then disconnect the house battery, taping a rubber glove over the cable end to make sure it can’t short out. Then disconnect the DC-DC charger or disable it. Making sure that all disconnected cables are protected from shorting out.

Finally get the house battery out of the rig, and place it somewhere that if it explodes or bursts into flames it will do little or no damage.

Then get the battery checked out by a specialist, not just any battery shop, but one that specializes in lithium/lifepo4. If the battery checks out okay, get both the DC-DC charger & the solar charge controller checked out to make sure they’re set right for that specific battery.

Next you need to check the wire sizes/gauges to make sure they are big enough, and check the connections. Then check to make sure you have the proper fuses/breakers FOR THE WIRE SIZE! The fuses/breakers should be sized slightly smaller than what the wires are capable of carrying. Finally make sure your inverter is working properly, along with any monitors you have.

No cable or connection should ever be even warm to the touch.


"Life can be as simple or as complicated as you make it.
Simple is cheaper and more reliable." ~ Off Grid

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Do not use cheap, low quality circuit breakers and fuse holders.

I strongly recommend that you get someone who is experienced with RV power systems to inspect your system and remove those cheap components and install high quality, marine grade components like BlueSea, etc.

Yes those components are expensive, but do you want to risk an electrical fire by using cheap, low quality components?

Hope this helps,