SOS! Battery died while hooked to shore power.

[Drought_Buster]

After a long winter, I hooked the Montana Fifth Wheel to shore power and reinstalled the battery that was stored in my basement. I went in and had power to the outlets, microwave... and all the lights came on bright. However, refrigerator, AC and stereo had no power. I quickly realized I had made a rookie mistake and hooked the battery up wrong (positive cable to negative terminal and vice versa). I switched the cables, tried it again and everything came on just fine (12 volt lights, outlets worked, microwave on, AC came on...). Waited a few days and put the slides out just fine. Five days later I went in and there is absolutely no battery power at all despite being hooked to shore power the whole time. Lights came on very dim for a few seconds and slowly faded out. So I assume I did something to the inverter when I hooked the battery up wrong. But if so, why did the lights come on bright both when the battery was hooked up wrong and once I turned it around? Seems like if I fried the inverter, the 12 volt lights would not work once I changed the cables around. Anyway, electrical is not my thing. Anyone have any clue what I did to end up like this?

[Drought_Buster]

I found my converter behind a hidden panel in the front storage compartment. Both 40 amp fuses were blown. I changed the fuses and pluged her back in and all seems to be worki ng properly. I will unlug it tonight to see if the battery reads fully charged on the message center, but it looks like I got her licked. Thanks for all the advice and help.

[wwest]

The reverse connection was long enough to boil off the electrolyte completely?

[2oldman]

Drought Buster wrote:
Roy, the picture you posted would not open...

Then you need to go to my forums, my preferences and click 'Show images that are part of posts.'

[lanerd]

bfast54 wrote:
Another remote possibility...Battery worn out.....Check water level,and if possible....Volts with a load on it.

At this age,4 plus years,batt could be weak.you just never know how good a battery is so if you do the other things also check the battery.
battery could be about 5 years old in a trailer of your age they dont always put brand new ones in.....the trailer manufacturers buy .... by the pallet load and they could be old

I agree with this post.

Have you checked the voltage of the battery itself? Remove the neg terminal and let the batter set for an hour or so and take voltage measurements with your multimeter. If it reads anything lower than 12.4 to 12.6 volts, you probably need to replace it.

[shadoow]

the reverse polarity fuses for the WFCO converter in my last trailer were located on the converter itself. There was an access panel built into the pass-thru wall nearest the inside steps that i used to get to the converter.

[Drought_Buster]

Roy, the picture you posted would not open so I Googled "reverse polarity fuses". The two images I found show panel boxes with the two reverse polarity fuses clearly marked, and as you mentioned, they are much higher amperage. I have only 15 amp fuses in my panel box, none of which is labled reverse polarity. I will keep looking around for other fuses, but I am very reluctant to try to take the panel box off to get behind it unless you think there is a good chance it is in there.

[Drought_Buster]

All of the fuses in the panel box are 15 amp and they are all in one single row. There are two fuses in the battery compartment, one is 15 amp and one is 30 amp. I changhed both of those and it did not help. I will go out now and see if there is anything that looks like the reverse polarity fuses.

[RollandB]

X2 with Roy's comments on taking a pic with. Cell phone camera. I do this all the time. Roy always has great ideas and is so helpful.

[bfast54]

Another remote possibility...Battery worn out.....Check water level,and if possible....Volts with a load on it.

At this age,4 plus years,batt could be weak.you just never know how good a battery is so if you do the other things also check the battery.
battery could be about 5 years old in a trailer of your age they dont always put brand new ones in.....the trailer manufacturers buy .... by the pallet load and they could be old

[RoyB]

Once you get things back to normal use your cell phone camera and take a photo of your battery connections and hang the picture is a zipup bag next to the batteries... Good use for cell phone camera...

[BobsYourUncle]

pianotuna wrote:
Hi,

Check the reverse polarity fuses on the converter.

What Don said. 🙂

Likely 2 of them in there, and could be inline fuses in the wires that only a mouse can find and see! They will likely be close to the converter.

[RoyB]

On a typical Power Distribution Panel you will find the REVERSE POLARITY fuses located on the 12VDC side of the panel usually off to them self. These will be be two high amperage ATC type fuse. You may also have a 3rd IN-LINE fuse blow which may be installed real close to the battery terminals. Some of the newer trailers use a 12VDC AUTO-RESET Breaker here.

The REVERSE POLARITY fuses are located almost in the center of this google search photo of a typical power distribution panel... (Two 40AMP ATC fuses shown here)



Make sure the battery is back to the correct connections before changing fuses otherwise it will just blow them again. I always look at the battery case for the word 'NEG' or the symbol '-' and make sure this is the battery terminal going to the trailer frame ground. If your trailer is using RED and BLACK battery cables this will be the BLACK CABLE... If you are using BLACK and WHITE cables then this will be the WHITE CABLE. Best thing is to hand trace them out regardless of the wire color...

Roy Ken

[Drought_Buster]

The humming or fan noise is coming from behind the panal box (with the breakers and fuses. There are four screws holding the panel box in. Do I just remove those and take the whole electrical panel box out to get to the converter? Do you know what a reverse polarity fuse looks lie?

[hmknightnc]

Drought Buster wrote:
Mini breakthrough. I flipped the breaker labeled "converter" and heard what sounded like a fan come on. It stayed on for about three seconds then went off. I flipped the breaker, waiter thirty seconds, flipped the breaker back on and, again, a fan or hum for three seconds and it went off. So it sounds like it wants to start but can't for some reason. The problem is I can't find the dumb converter to take a look at it.

It's probably behind a panel right below those breakers. Find it and replace it, also check those reverse polarity fusses since you hooked the batteries wrong