Battery leads reversed

[mitw44]

I usually take my battery off my travel trailer at the end of each trip and put it in my shop, so that I can keep it charged up. I have done this for years with no problems.

Today, I must have got distracted while hooking up, and I reversed the leads to my battery. When i got to my campsite several hours later, I hooked up to shore power, but could not get the refrigerator, AC, or lights to work. But the power stabilizers and the outlets all worked. I was really confused why some things would work but not others. The camp host confirmed that the power pole was supplying 120 volts, and even changed the receptacle.

Finally, i had to call a mobile tech, and in 5 minutes found the problem. It had blown two 40 amp fuses, which he replaced, and after correcting the battery hookups, and I was back in business.

He explained that the plug ins worked because they drew AC straight from the power pole, but that even though the AC and fridge ran on AC, they received control feedback through the DC loop. I wish I had known that before, so hopefully, sharing this might help someone sometime.

I plan on installing a battery disconnect, so I don't have to take the battery out of the travel trailer. Are there any other suggestions for an add on to protect my rig from low or high voltage, reversed polarity, a miswired battery, or voltage spikes, etc while I am thinking of upgrading and protecting my electrical system?

[RedRocket204]

Aside from the other suggestions to color code the cables (great idea) and the suggestion to install a solar panel/controller (never have to remove your batteries again!), now is the time to take a picture of how those cables and batteries are wired. Keep that picture on your phone and/or print that picture to use as reference and keep it in your RV. That picture will be a valued resource if you ever need to disconnect the batteries even after color coding everything.

[mitw44]

I did notice my stereo doesn't work. There is a fuse in the panel for it, but I haven't checked it yet. Everything else seems to work.

[MEXICOWANDERER]

Hah. The color coding is an aid, not equivalent to a brain transplant. I remember an idiot boat owner who sneered at my suggestion he disconnect and reconnect his 4 8-volt batteries the intelligent way Negative First Off and Last On. He swung my 1/2" long combination wrench and sure enough it shorted against the hull.

The first I saw of it, was a blue arc flash all the way across the engine room. Not only did he melt my wrench, he blew the positive post off a 330 amp hour battery and melted a hole a person could stuff an orange through of a 5/16" steel hull.

Even though he had been by himself for 10 minutes and I was twenty feet away doing a generator reconnect, he bawled "I was distracted and no I am not going to pay a cent for your (almost new) wrench"

Well it was either me, to fix another lead L-pad onto that battery or spend three hundred dollars for another battery. Heh heh heh. Wotta fool. He even received an arc flash eye burn.

And 2X Mr. Soren's advice. Meticulously check every function of 12 volt device.

[soren]

I had a chucklenut service guy do this to my motorhome, at a repair shop, as he tried to charge a dead battery. He obviously blew the reverse polarity fuses out of the brand new multi stage converter I had just installed. It was unpleasant to fix, as the converter is really buried deep under the fridge, behind the 120V panel. After replacing them, everything worked but the two rooftop AC units. I was a little sick and gave Winnebago's service line a call to ask their opinion. It only took a minute for a really knowledgeable Winny employee to tell me that each wall mounted T-stat has an old fashioned, glass, mini-cartridge fuse hidden behind the cover. Once I swapped those blown fuses out, everything was fine.

Bottom line, if you reverse the cables, and blow the big fuses in the converter, there may be smaller ones hidden elsewhere that also got hit. In my case all the color coding in the world wouldn't of helped. There are red and black cables on the terminals, and zippy had red and black battery charger clamps in his hands, but it was still beyond his skill set.

[Bobbo]

I didn't think breakaway brake switches could be fused by code.

[YC_1]

That fuse could be a charge line fuse from your tow vehicle. Not very big but it still could be. Or perhaps a break-away fuse. If you become uncoupled it would engage the electric brakes.

Fuses can be bought individually or in a variety pack. Many rv parks sell fuses. Any automotive parts stores has rows of them. Walmart probably has them.

[westend]

A piece of Red heatshrink installed on the positive battery cable is a good alert to the proper polarity. I also use Black heatshrink on the (-) phase cable.

[IAMICHABOD]

mitw44 wrote:
All good suggestions that I will implement.

First question: Where can I get an assortment of these type of fuses? Even if I had trouble shooted the problem correctly, I would not have had the fuses. Do auto parts places carry these?

I carry This Kit and This One Scroll down on the first one and you will see Frequently bought together They pretty much cover all my needs,although I haven't needed them yet.

[Bobbo]

mitw44 wrote:
Another question. So, what is the 15 amp fuse under the front of the trailer near the battery? It's in a little case inline with the wiring coming from the battery.

My first thought was the inline fuse to the tongue jack, but mine is 30 amps. You may have to trace the wire to see what it runs to.

[MEXICOWANDERER]

A little ring binder, with plastic sheet protectors. Write down fuse numbers. Then alongside that describe WHERE you stuffed the spare fuses within your rig.

[mitw44]

All good suggestions that I will implement.

First question: Where can I get an assortment of these type of fuses? Even if I had trouble shooted the problem correctly, I would not have had the fuses. Do auto parts places carry these?

Another question. So, what is the 15 amp fuse under the front of the trailer near the battery? It's in a little case inline with the wiring coming from the battery.

My dealer did a pretty thorough PDI delivery walkthrough, and did show me the main fuse panel, but didn't share a lot of detail on what was in it. Or what would happen if I ever reversed the battery cables.

[wa8yxm]

The Reverse polarity fuses saved more than his converter.

Also a Surge guard WILL NOT PROTECT against this error.. Several others yes. This one no..

At Risk when you hook up backwards are all your 12 volt electronics This includes the controls for Fridge, Water heater, Furnace and optionally the A/C (Some are suspectable some are not. One of mine is One of mine is not)

Some lights as well

Suggestion.. Get a can or two of spray paint,, The little testor's cans are good for this, you can also use nail polish

RED and Black

Red goes on the POSITIVE wires, as connected, over spray onto the battery is acceptable and in fact a good thing

Black on the negative side

WHILE THEY ARE HOOKED UP PROPERLY.

[MEXICOWANDERER]

My son in law was amazed when I showed him my little trick...

RED AND BLUE Krylon paint for plastic

Red for positive. Clean off the post and terminal then hose it all with red.

Blue for negative. The hardest part is doing the prep work. Yes the case gets splotched too. Not a cute little dot slop the color all around the post as well.

This is SMART prevention. I do not have time to tear off my safety googles, find my reading glasses to find a 1/2" tall +plus+ near the positive post.

[mitw44]

It's a 2017 Salem Cruise Lite XL, and( runs on 30 Amp. The cables are still colored. I usually put the battery in the case with the terminals closer to the RV. For some reason, I flipped it around, and must not have noticed the little black raised "+" and "-". Between car, motorcycle, lawn mower, tractor, rv, etc. batteries, I have never made this mistake from age 16 to 52. All it takes is once, I suppose.

And, yes, I then followed up with questions on how to protect my main electrical system above and beyond this battery issue. I have heard of other people on this board having issues from the power pole and want to proactively deal with it all now.

It hurts my pride a little to admit my rookie mistake, but I thought someone might learn something. I certainly did!

In the manual, on page 4, it says" If the reverse polarity fuses are blown, it means the RV battery was accidentally connected in reverse". It goes on to give a pretty good description.

I want to thank everyone for their helpful input.

I will get the EMS and look into getting a solar panel.