Shore Power fine; no electric when on Batteries

[MissingLink5]

Just this past week, on my way to a rally, I had no electricity while hooked up to tow vehicle on the road to run refrigerator on gas or LED lights in airstream; all outside lights (running lights) worked fine. The power switch was turned on next to the door way; batteries were charged and held a good charge and I was hooked up to tow vehicle. Once plugged into shore power, either 20amp or 30amp everything was fine. I checked all breakers and 20 & 30 amp fuses in electric panel and all good. I religiously use CRC Electronic Cleaner on both male and female contacts on plug. Never happened before! Any suggestions. I have a 2006 25' Safari SS SE.

[J. Morgan]

Maybe your batteries were simply discharged, and the fuse on your tow vehicle for the trailer hot line is blown.

Check to see if the batteries are taking a charge now that you are on shore power.

[HiJoeSilver]

Exterior running/tow lights get power from TV and ate separate from trailer 12v.

Going on your stated items being correct, batteries charged, 12v power when hooked up to shore power indicates that your converter charger is working which provides 12v while hooked up to shore power. So there's a problem between your battery and 12v system. May be a bad relay which is controlled by the use/store switch keeping battery from providing voltage.

[uncle_bob]

Hi

A lot depends on exactly how *your* trailer is wired. Even if you have the schematic for your model and year, there is no guarantee that your specific trailer is wired that way.

Case 1: Converter is on the "store" side of the use / store relay (or switch). In this case, your batteries are toast.

Case 2: Converter is on the "use" side of the relay. In this case your relay is toast.

Yes, both of these are best guesses. The real answer is to dive into how your trailer is wired and check out each sub-system. You may find that an inline fuse somewhere is blown ... lots of possibilities ....

Bob

[mythbuster88]

I'll bet the connections are loose at the relay.

[rvb]

3 months after buying our Minuet it had no 12v power. I had already replaced the glass fuses with a modern spade fuse box, installed a Trimetic meter and checked everything except the battery terminal connections. They looked fine but the positive terminal was so loose I could just twist and remove it and the inside of the terminal connection was black with oxidation. After cleaning and clamping tight all it now works fine. Try cleaning and check the battery terminals.

[NWRVR]

You may have a failed solenoid/relay. When we were going through our walk-through on our 2014 Serenity they could not demonstrate how the in-use switch worked after shore power was unplugged; no 12V power. They replaced the solenoid/relay and all was well.

[brian0724]

I have a 2006 25 foot FB Safari SE. Had the same problem you describe, and, as recommended above, it was the relay that is controlled by the Store/Use switch. I understand it's a common problem on Airsteams the age of ours. I bought a new relay on the internet and swapped it out myself, or you can have a pro do it for a moderate fee.

[guskmg]

Causes: No fuse installed in the truck DC trailer power circuit, a broken wire, a loose or dirty connection between the truck battery, trailer pigtail (both ends), Pigtail J (junction) box located near the floor and left interior wall of the trailer, or the DC power wire connections from the J box to the DC battery bus. I have seen loose connections either from vibration or left loose during installation.
With a test lite, check for power from the truck battery to the DC bus bar where all the individual circuits connect in the trailer. Also check the same for all connection all the way back to the battery (ies). If that checks OK, then you may have a high resistance connection that is preventing a normal load to pass through. We are talking about loose/dirty connections on positive and negative circuit connecters (terminals). Clean them with your contact cleaner and smear some dielectric silicone grease on them. Happy hunting.
guskmg

[J. Morgan]

You need a test light.

[MissingLink5]

Thanks everyone for your comments and suggestions. It was a small amount of corrosion on the black (negative) battery connection. Took both off and scrubbed and put baking soda & water on them and all things work fine. Amen!!

[MissingLink5]

Thanks, guskmg. You hit the nail on the head! I had looked at battery cables but hadn't initially seen the corrosion. A simple thing as that can cause a lot of problems. As an old farm boy it should have been the first thing I tested!