How does batteries get power from the tow vehicle?

I have a 2007 Yukon with the. GM style 7 pin connector. I checked and I get 13.5 volts to pin #4.

When I plug in the TM I notice that I only get 12.5 volts at the batteries at the tongue. I followed the wire harness from the male plug back along the trailer and only two wires leave the sheath near the tongue and those are two wires that go to the brake disconnect (break away) switch. All of the other wires do to the rear of the the TM and I assume the 12 V power feed wire goes to the power converter and distribution box and then one wire heads forward again to the battery box on the tongue.

I notice when I use booster cables connected directly to the battereI get the "Charging "light in the System Monitor. When I connect the 7 pin connector I do not get a charging light.

I checked all of the fuses in the distribution box. The instruction manual was poor at best.

Does anyone have any suggestions?

[Riwright]

Search for threads that have to do with running the refrigerator while driving. A lot of people see the frig in DC mode running down the battery because the amount of current that makes it from the tow vehicle to the camper is too small. Sounds like you have a similar problem.

Usually there is a voltage drop between the tow vehicle and the battery. The wiring runs can get quite long. Installing heavier gauge cable will usually help.

I recommend the yearly membership. If you own a Trailmanor there is a lot of good information here.

Unless I misunderstand your post, you are simply seeing the voltage drop under load. I don't see an issue. Is there something not working or other issues? Is your battery discharging when connected to the TV ?

I'm pretty sure it's the center pin in the 7 pin connector that is the "charging voltage" from the TV

[Bill]

Originally Posted by Redhawk

I'm pretty sure it's the center pin in the 7 pin connector that is the "charging voltage" from the TV

Umm, no. According to Bargman and other sources, the proper connections can be seen here

http://www.trailmanorowners.com/foru...&pictureid=442

For what it is worth, I have seen a number of pin-numbering schemes, so I no longer even try to refer to "pin #4" for instance.

But I agree that it sound like simple voltage drop under load. In this case, the "load" may be the TM battery itself, as its charging current flows down that long wire from the tow vehicle alternator - especially if the Yukon's engine was not running when the measurement was taken.

Bill

Thanks for the reply.

Since I am living in my TM at the present...driving cross country in a trailer that I just bought...with only my computer "tethered" to my cell phone for brief moments in time...I have not had time to officially sign up however I will pay the 12 bucks as I get a chance. As a new "visitor" I do get the full features of the forum and I have pretty much read most of the pages and used the search function as much as possible...

Getting back to the charging through the trailer connection...when I first bought the trailer the "charging" light would illuminate when the TV was plugged into the trailer and I had the Yukon engine running....THEN...one night back in the woods when it was 30F outside I woke up to find that both of the batteries of the TW were dead AND the Yukon battery was also dead.

I knew what the problem was...When I bought the TM three weeks ago the single marine battery was completely dead. It charged up while towing and it seemed to work fine in Tucson where I did not need the heater (it was connected to the Yukon all night). Since I am planning on using the TM for extensive "Boondocking" I decided to go ahead and install a second marine battery and I thought all was fine until that one cold, dark morning. I have since replaced the old battery with a new marine battery and since now I have two marine batteries the system works really well even though it is very cold here every night (I do run the heater extensively since the King bed is kinda cold way in the back) I still wake up to the batteries showing "good" to "fair" on the System Monitor without the Yukon connected up (I will not fall for that trick again).

Anyhoo...before the dead battery morning the charging light would light up as I ran the Yukon engine with the TM plugged in...now the charging light will only illuminate when I connect Booster cables to the TM and do the old fashioned charging.

Does anyone know if the charger controller has some kind of circuit that limits the charge of the batteries during 12VDC operations?

I am considering splicing into the wire bundle near the tongue and tap into the 12 VDC feed wire right at the tongue and run a fused 10 gage wire directly to the battery bank so that there would be no voltage drop from the tongue to the charger controller...in the charger controller...and then back to the battery bank.

[Bill]

The "charge controller" - actually part of the converter - plays no part in what you are discussing. The charge line from the tow vehicle goes directly to the TM battery, and there is no "controller" involved.

As for the second issue, if your Yukon battery went dead, then you need an isolator in the Yukon. I suggest most strongly that you get a relay-based isolator, rather than a diode-based isolator. Use the Search tool on the term "isolator" to find a lot of discussion.

Bill

[Brittany Dogs]

The general rule of thumb, as I remember reading one time, when a deep cycle or car battery is run down to almost nothing (as in a really dead battery) the life of the battery is knocked in half.

Do that again, and the life of the battery is knocked in half again.

So a new battery, that might be good for say six years, will be good for only three years. If you run it down to almost nothing again, expect only a year and a half out of it.

[rvcycleguy]

Brittany, A car battery, yes. deep cycle battery,no. It's designed to be depleted down before recharge.

Thanks for the correction on pin 4 Bill... I should have known there would be different ones out there. Just spouting off from my experience.

Sounds like the OP could benefit greatly from a solar setup.

Originally Posted by rvcycleguy

Brittany, A car battery, yes. deep cycle battery,no. It's designed to be depleted down before recharge.

Deep cycle batteries can be deeply discharged ( 80%) but should not be depleted. Ideally they should be recharged after about 50% for max life. Here is a great technical site on batteries and recharging ( as well as solar.) There is also a great battery voltage reference chart. I printed and laminated several and use them in my TM as well as home.

http://www.windsun.com/Batteries/Bat...ery%20Charging