Got a call from a friend...

[ken56]

My good friend called me today and told me his 12 volt side of the trailer does not work when he is not plugged into shore power. No lights or refrigerator or anything else 12 volt is getting power from the battery, he must be plugged into shore power for anything to work and all is fine and works normally when plugged in. Any suggestions on what to look for? Its a new battery and he just put in a new converter because it was not charging the battery. Not sure if he hooked it up correctly or if he missed a wire to power the 12 volt from the battery when not on shore power. Any Ideas?

[wa8yxm]

guidry wrote:
It’s gotta be the converter if the battery is good. That’s usually what happens when someone plugs into a bad power source and blows the converter.

His 12 volt won't work unless he's plugged in.
UNLESS he has something like a magnetek 6300 series.. The one part Id not suspect is the converter for that is why his 12 volt works when he's plugged in.

Now the other thing I'd not suspect is the reverse polarity fuses for they are part of the converter assembly.

Battery disconnect system and battery protection fuse or breaker. Suspects one and 2.

Bad ground on battery negative bad connetion on battery 3,4 and 5

Bad wire 6 a very distant 6

That's the list.

[enblethen]

Thanks for he update!

[ken56]

It was the 40 amp circuit breaker. We took apart all connections and cleaned the corrosion and replaced the circuit breaker and all is well now.

[ken56]

Thanks everyone for the ideas. I made notes to take over. While I'm not an expert here I am also not totally uneducated about 12 volt systems, just though I would ask on here for what to look for. Personally I think its his battery fuse/breaker or possibly corroded connections....his trailer is 8 years old and was purchased used from a dealer and appears to have been stored outside all its life. Thanks again, will update later.

[wa8yxm]

I need to boiler plate this
Get an Automotive Test Light (Most any auto place) looks like an old fashing ice pick with a light bulb in the handle and a wire coming out with a clip on it.

Touch clip and tip to battery posts. Bright = GOOD dark either the bulb needs re-seating or battery is dead.

Once you have bright move clip to any unpainted metal frame part (Good ground) and touch battery positive with tip. Bright = Good dark try a different clip point.

Can not find bright.. Negative cable issue check both ends and/or jumper around it for testing. It may need replacement (Bad wire does happen)

Else
Move out along the positive wire.. Every terminal check IF you move the ground clip re-check last point to insure good ground. problem exists between Dark and Bright.

[2112]

If the battery is good, properly connected, and the battery disconnect switch is not turned off, follow the battery positive cable to look for something like this:

[guidry]

It’s gotta be the converter if the battery is good. That’s usually what happens when someone plugs into a bad power source and blows the converter.

[time2roll]

What is the battery voltage right on the terminals?

s/b same as converter voltage or you have an open connection. Find the bad spot and fix it.

[enblethen]

Reverse polarity fuses are good as the system works when plugged into shore power.

[BB_TX]

Did he by chance turn the battery disconnect switch?

Or he could installed the battery wired reversed polarity. Happens more often than it should. Will blow the reverse polarity fuses.

[enblethen]

Should be a fuse adjacent to the battery on the trailer.
Could also be another battery in the 12 volt DC distribution panel possibly marked BAT