Fuse at battery keeps blowing

[tyjdavis]

Hey all,

We got our 2006 Jay Feather 232 (handyman special) last month and I’m digging into the repairs.

There was a 25a fuse in-line off the negative post of the battery. All of my negatives are nutted together and the fuse holder is the only thing on the battery. Well, I installed the AiLi monitor (with shunt) so the fuse mounts to the shunt and the shunt is the only thing connected to the battery. This fuse blows instantly when trying to run off of battery power.

I need some guidance. Near as I can tell, there is no manual breaker on my rig. Is this fuse necessary? From what I understand, it’s there to protect the wires, not the appliances. It also needs a roof, so I’m trying my best to remove roof components in the freezing cold. I have the interior part of the AC off and the electrical is nutted off separately.

Photo is of my shunt. Blue wire nut is all of my negatives, black and white wire is my breakaway switch for brakes.

Thanks in advance folks. Real newbie here with a failure to understand electrical systems.

[Shokyle1]

You usually do not see ground circuits fused.

[Grumpy]

Fuse should be on the positive side. Are you sure the battery is installed correctly?

[craigav]

As others have stated, you don't normally see fuses on the ground side (negative) however I wouldn't go without a fuse there unless you know for sure you have a fuse on the positive side as even with it being on the negative side, it will still protect your wiring if you have a short circuit. I would suggest to turn everything off 12v and try again, if you still blow the fuse then you either still have something on that is pulling more amps than the fuse is rated for or you have a short which would need to be further investigated. On an older trailer I had many years back I searched everywhere for a short and finally found the problem was with the electric trailer brakes. ~CA

[craigav]

I suggest that adding more pictures may be of value, in particular a picture or two of the wiring on the battery itself and as best as you can where the wires off of the battery are going. I had a thought after my last post that perhaps the fuse was wired correctly and was meant to be connected on the positive side of the battery and you (or some unknown person) connected the fused connection to the negative battery terminal instead of the positive terminal connection. If so, that would blow the fuse instantly. ~CA

[tyjdavis]

Photos of battery, where the black and white wire goes to the brakeaway switch, and where (I assume) the battery goes to at the opposite end of the trailer (so that’s easily 25ft of cable), to the DLS-45 converter.

[tyjdavis]

I’m thinking if the white wire is coming off the positive on the battery, then it should be going to the receptacle on the converter with the red dot. So maybe switching the battery wires is the solution?

[ALJO]

White wire on the plus, is incorrect. White should be on minus/ground to chassis.
Black is plus side.

[JFlightRisk]

I may be seeing something incorrectly, but the black cable on the negative battery terminal seems to be connected to the positive side of the converter. I see a red dot sticker where it's connected, which would make me believe it's the positive terminal.

[Grumpy]

Originally Posted by JFlightRisk

I may be seeing something incorrectly, but the black cable on the negative battery terminal seems to be connected to the positive side of the converter. I see a red dot sticker where it's connected, which would make me believe it's the positive terminal.

YEP, battery is connected backwards...

[craigav]

Originally Posted by Grumpy

YEP, battery is connected backwards...

I agree, one thing a lot of people don't realize is that on a car black is often negative, but not for an RV where black is positive. ~CA

[JimD]

One way to determine which wires are negative is to disconnect the battery cables and take a resistance reading to the metal chassis. The negative cable will read zero ohms while the positive cable will read well above zero depending on what loads are connected and on at the time.

[craigav]

Originally Posted by JimD

One way to determine which wires are negative is to disconnect the battery cables and take a resistance reading to the metal chassis. The negative cable will read zero ohms while the positive cable will read well above zero depending on what loads are connected and on at the time.

In fact I was going to reference your troubleshooting articles to tyjdavis in case he was\is not familiar with using an vom meter (voltage ohm meter) and the issue was more than what it was, to troubleshoot issues like this.

tyjdavis, take a look at the following two documents that Jim put together, and then if you don't have a meter, you should get one.

Jim, is this the correct link to the latest of your informative troubleshooting articles?

https://www.jaycoowners.com/forums/f...ies-83176.html

~CA

[JimD]

Originally Posted by craigav

In fact I was going to reference your troubleshooting articles to tyjdavis in case he was\is not familiar with using an vom meter (voltage ohm meter) and the issue was more than what it was, to troubleshoot issues like this.

tyjdavis, take a look at the following two documents that Jim put together, and then if you don't have a meter, you should get one.

Jim, is this the correct link to the latest of your informative troubleshooting articles?

https://www.jaycoowners.com/forums/f...ies-83176.html

~CA

Yep, that is the correct link. The only thing is that you have to scroll through some posts to get to the revision 2 release.

[tyjdavis]

Occam’s friggin’ razor (problem solved). Wires were backwards. Thanks all.

[JFlightRisk]

You're very welcome. Sometimes a second set of eyes see thing differently in a picture, and we all like to help out here. Happy trails!