Battery charging from tow vehicle ?

[rwnash]

I am sure this must have been discussed but I had no luck with the seach function.

In the process of replacing the "break away" emergency switch I was tracing the wires from the tow vehicle connector. With the trailer plugged into shore power I was getting about 5 volts across the battery and ground terminals. With the trailer unplugged the voltage jumped to 12 while the supply to the electric jack was 13.8. Obviously there is something in the circuit that prevents the plugged in trailer from "charging" the tow vehicle. My question is what/where is it and will it allow the tow vehicle to charge the trailer batteries given that there seems to be a large ( 1.8 volt) drop in the circuit?

I don't have a wiring diagram for the 1986 25 foot AS. The 12 volt fuse panel is behind the front sofa and the charger is there somewhere. (To be honest I have not had the need to check them out - so far - and am not complaing about it.) Does anyone have any experience with this situation and are my observations "normal"?

Years ago my parents had a travel trailer and I never thought the tow vehicle did a good job of charing the battery; I attributed that to the long and undersized wire between the two batteries.

Thanks for your help

Whit Nash

[richinny]

these threads might help you.

http://www.airforums.com/forums/f398...cle-42615.html
http://www.airforums.com/forums/f449...cle-14809.html
http://www.airforums.com/forums/f449...icle-9629.html

[purman]

Man when I bought mine a month ago the battery charge wire was hooked up to the reverse lights so when I plugged it into the tv my reverse light on the tv came on... took me about 1/2 hr and a wiring guide to get all the wires right. But the battery charges great...

[rwnash]

Thanks for the information.

I have a bit more thinking to do after reading the other posts - but I probably won't put in the 4/0 charge wire! (That stuff is bigger than what feeds my house.) Anyway, I may hook up a meter and see what goes on with my existing setup. I'm heading out for a couple of weeks off the grid in late August - hope that the two batteries will keep me going.

I can relate to "non standard" tow vehicle connections in the past. A friend bought an old Avion in the mid 70's and - without enough checking - took off camping. He was traveling behind us and wanted to signal to pull over for lunch. The agreed signal was "headlights on" which is what he did - and the trailer brakes locked up! Things are better today - I bought a new utility trailer 5 years ago and everything worked as it should when I picked it up.

Thanks again,

Whit Nash