Battery wont charge from TV

[Bernbob]

I'm having a problem with the TV charging the battery on my TM. I have a 2006 2720. Shore power charges it just fine, but the TV is definetly not charging the battery as we are going down the road. I have had the TV connector checked and it is just fine. Cleaned both TV and TM connectors, checked all fuses, replaced the battery with a larger deepcell and replaced the 30 amp fuse at the battery with an automotive type. The converter seems to be working just fine under all circumstances. I'm not extremely electrical savy. Is the converter in use when charging from the TV? Is there a fuse somewhere that I can't see without taking something apart? Just hoping that this might be a simple fix! By the way. TM is a great product, and this forum is outstanding. Have learned a lot from reading the posts and am just amazed by the help given by all of you.

On some Tv the proper terminal in the umbilical is not energized, there are some posts about them in the archives here. Some people have run a cable from the battery in the TV back to the connector at the rear and wired that to the correct terminal.

What TV do you have?

[Bill]

Originally Posted by Bernbob

I have had the TV connector checked ...

What does that mean? Who checked it, and what did they check for? As the Greek historian wrote, there have been a surprising number of tow vehicles reported in which the battery charge line in the connector is not energized. Usually this is due to the fact that there is a fuse in the tow vehicle that wasn't inserted at the vehicle factory - no one knows why.

To check it, you need to start the tow vehicle's engine without the trailer connected, and check the pins in the tow vehicle half of the connector with a voltmeter or test light. You can see a diagram of the connector here

http://tmphotos.org/modules/xoopsgal...?g2_itemId=187

As you can see, the charge line is located at one o'clock, and ground is at 7 o'clock as you look into the connector.

If this test is difficult for you to run, there is an alternative of sorts. First, disconnect the TM battery - either pop out the inline fuse, or take one of the battery wires off its terminal. Then plug the TM into the tow vehicle, start the vehicle engine, and turn on some lights in the TM. Make sure you turn on lights in the front shell if the bathroom is not set up. The lights should light, powered by the tow vehicle. If they don't, then the tow vehicle is definitely not providing power to the TM, and the problem is almost (but not quite) certainly in the tow vehicle. To be sure, you really have to go back and run the first test.

The converter runs only when you have shore power.

Let us know what you find.

Bill

[Bernbob]

My TV is a 2006 Toyota Tacoma. I had the charge terminal checked at a rv dealership while we were on vacation. They checked all terminals in the connector on the TV to be sure there was nothing wrong, and everything checked out on the TV end. I have also tested the connector on the TV with a test light and all is well. I guess the next step may be the connector on the TM. I will let you know what I find.

[Bill]

OK, it sounds like you are doing the right things. The next test (I should have included it above) - make sure the TM battery is connected, unplug the TM from the tow vehicle, and then check the TM end of the Bargman plug with a test light. Do this with shore power disconnected, and again with it connected. In both cases, you should see 12 volts (the light should light) because the charge line is connected directly to the TM battery, interrupted only by the battery fuse.

If you don't find power here, then the problem is in the TM, and the next step would be to check an intermediate point. I believe that the first place that the TM car cable goes is under the kitchen sink, where the connections to the rest of the trailer are made. If it is like my 2720SL, the connections are made in a small wooden box that it easily removed. Space is tight under the sink, so it gets a little unhandy to check things there, but all 7 wires in the cable branch out from here.

Again, let us know where you go with this.

Bill

[Bernbob]

OK, here is what did this morning. I disconnected both leads at the battery on the TM. I then connected the TM and the TV connectors, with engine running. All lights in the TM worked. Then I went back to the wires at the battery on the TM(still disconnected) and tested to see if I was getting power to the battery, and I was. So, here is the complete story. Leaving a campground with full hookups, battery is fully charged. Not having anything running in the camper as we are going down the highway and arriving at the next campground, battery is fully charged. Going down the highway with the fridge on battery, battery is generally 1/2 to 2/3 discharged. Is this what an interruptor does on a TV, protect the TV so that the alternator does not put out so much that it burns itself up? We resolved ourselfs to not running the fridge going down the highway and it was ok. Is this what everybody else does? I can live with that.

Bill had a good post on wire size and that may be the problem, don’t know if you will be able to search it as a trial member. When the Connector on the TV was checked for voltage was it also checked under a load, You may find there is a significant voltage drop if the TV’s wiring isn’t heavy enough. You still haven’t said what model TM you have. Does the power wire on the TM run from the Bargman plug to the converter then back to the batteries, if so there may be too much of a voltage drop over the wiring while the fridge is running. You need 13 1/2 volts at the batteries to charge them. When I checked the charge going to my TM batteries with the TV running and the fridge on, I was only getting 12 ½ volts, not enough. I’ve replaced my TV’s factory installed tow package wire with 8 Ga. And gained a half volt under load. I plan on replacing the 12 ga. wire from the Bargman plug on my TM with 8 ga. when I get home this week. I’m far from an expert on this, only trying to pass on what I picked up from others. Here is a site that lets you figure out all the voltage drops for different loads and wire size. Just scroll to the bottom and fill in the blanks on the easy to use calculator.

http://www.powerstream.com/Wire_Size.htm?nowritefs

[mcgyver210]

We have only been on one trip so far but when I setup the wiring for the P3 Brake controller & the charge wire I used 8ga strand wire for the charge wire run directly from the battery with an in-line fuse block. We drove about 5 hrs stopping once at Trailmanor corp. & then going on to the Gatlinburg campground. We did check the battery guage at Trailmanor & it was full still. When we setup in the campground we also checked & again it was full. My only issue has been figuring out what size fuse I should use in the fuse block.

It appears that you are getting 12 volt power from the TV back to the TM batteries. However, it is not enough to run both the fridge and charge the batteries.

The first two things that come to mind is that the charge wire is too small or the alternator does not produce enough current(amps).

Check the wire size and verify that the alternator is putting out enough current. I do not know what a minimum sized alternator would be but perhaps someone else does. Usually any TV that has a factory or dealer installed tow package has a larger alternator. I *THINK* the alternator in my truck produces 140 amps. I know that I can run the fridge and charge the batteries.