Power to Rig

If there is only one wire from the trailer to each battery terminal there is no reason I can think of that having the trailer connected to the tow vehicle battery via jumper wires wouldn't supply 12V power to the trailer, especially if you insured via measurement that you were getting 13.4V at the trailer terminals.

Interesting puzzle. When the battery is in, it should have a wire to the Rv frame to make the negative path to the DC fuse panel, which does have its own neg wire to the frame. The frame is a major part of the neg path.

You jumpered to a neg wire and two pos wires and it didn't work. I am thinking there is a missing neg wire that goes from the battery to frame that you did not connect to, and that the neg wire you did connect to is for something else.

To solve that possibility, clamp the jumper neg to somewhere on the frame instead of that neg wire, and the jumper pos to the two pos wire terminals and see if that works.

If not then the pos path must have an open, such as the disconnect switch or the fuse/DC circuit breaker there.

mgirardo wrote:
When we closed up the TT last summer for the season, we left it at our seasonal site. I removed the battery and dropped it off at my in-laws so my father-in-law could keep it charged for us, we didn't have the room to bring it home.

When we got back to our seasonal site this past spring, we got there a little later than expected (darn Virginia traffic), so I didn't stop at the in-laws to get the battery.

I figured I'd be able to use jumper cables the same way you did so I could get the slides out and use the pump to evacuate the anti-freeze. Nothing 12v worked. On our TT, there is 1 cable that goes to the negative terminal and 1 cable that goes to the positive terminal. Both of them are marked with a label. I connected them properly, but still no 12v.

The jumper cables were in fine shape and when I tested them with my volt meter, there was 13.4v with the engine idling. I even had someone go in and press the gas pedal a little, but there was still no 12v in the TT. There is no battery disconnect switch in our setup. Since we were at our camp site, I just removed the jumper cables and plugged the shore power cable up for power. I picked the battery up a few days later. After connecting it, I checked the 4 reverse polarity blade fuses and they were all good.

In theory, there is no reason the jumper cables wouldn't work. I'm not sure why it didn't work.

-Michael

That's what I am thinking. Simply doesn't work for whatever reason.

It is difficult to connect jumper cable clamps to those little ring terminals. Works to use vice grip pliers on the ring terminal and clamp to the vice grips, or put a nut and bolt in the ring to give something big to clamp to.

When we closed up the TT last summer for the season, we left it at our seasonal site. I removed the battery and dropped it off at my in-laws so my father-in-law could keep it charged for us, we didn't have the room to bring it home.

When we got back to our seasonal site this past spring, we got there a little later than expected (darn Virginia traffic), so I didn't stop at the in-laws to get the battery.

I figured I'd be able to use jumper cables the same way you did so I could get the slides out and use the pump to evacuate the anti-freeze. Nothing 12v worked. On our TT, there is 1 cable that goes to the negative terminal and 1 cable that goes to the positive terminal. Both of them are marked with a label. I connected them properly, but still no 12v.

The jumper cables were in fine shape and when I tested them with my volt meter, there was 13.4v with the engine idling. I even had someone go in and press the gas pedal a little, but there was still no 12v in the TT. There is no battery disconnect switch in our setup. Since we were at our camp site, I just removed the jumper cables and plugged the shore power cable up for power. I picked the battery up a few days later. After connecting it, I checked the 4 reverse polarity blade fuses and they were all good.

In theory, there is no reason the jumper cables wouldn't work. I'm not sure why it didn't work.

-Michael

Most likely cause is a missed wire.. What I tell people who remove batteries is

1: Paint all positive leads RED (Optional paint negative black) These are TRADITIONAL not Standard colors. there is no standard.

2: Photo shoot

3: If multiple leads hooked to the same post (Except for battery to battery jumpers) TIE them together Or in your case BOLT them together. Insulate the positive Plastic something.. IE: Surgar Free Water flavor (Crystal Light is a brand name) and a wrap of tape or poke a couple holes and "Tie" it on)

YOu likely popped a breaker.

Question asked in another way,....
one 12v battery works, the other one don't,....why ?

Maybe THINK for a moment,....how difficult can that be ??

Lynnmor wrote:

Hoppypoppy wrote:
Thank you all. I tried the power cable to the truck. No worky. 12 volt switch in right position. Bumfuzzled. Will try running neg to neg and connect the two pos RV cables and try that. Thanks again.

Did you hook it up backwards the first time? Is the reverse polarity fuses now blown?

No, didn't hook it up backwards.

The negative terminal on your truck battery should be connected to the wires on your trailer that connect to the negative terminals on the trailer battery and the positive terminal on your truck battery to the positive terminals on your trailer. If you had them reversed you have blown the reverse polarity fuse on the trailer and possibly a second reverse polarity fuse on your trailer's converter.

Sure hope you remember how those cables were hooked up. Many don't.