Trailer battery not charging while traveling.

Hi, I haven’t posted for a couple of years, but I do browse once in a while. We have a 2002 24’ DL silver edition that we bought new and enjoy very much.
Now we have a problem when we get to a campground after several hours traveling and the refrigerator running on DC. The top section does not want to go up. When I press the switch to put the top up, it starts to go and then the battery dies. I can check the battery level and it is almost dead. If I plug the AC line into the campground box for a few minutes while we put the stabilizers down, then the battery is charged enough to put the top up. In a couple of hours the trailer charger has charged the battery to full charge. I have checked all the fuses. There is 12V at the TV receptacle on the charge line. At the trailer plug there is 12V on the charge line from the trailer battery. That means to me that the fuses are good, no blown fuse that is hidden and the wires are good. I have also had the battery tested and it tests good. Sorry this is so long but I wanted to tell what I checked and have found.
Does anyone have an idea as to what the problem is?

Running the refrig on dc often takes more juice than your alternator can deliver to keep it going and keep the trailer battery charged. So- your fridg is taking more out of the battery than you can put back in. Often this is because the wire from your tow vehicle is not thick enough for the distance it must travel from the alternator and there is a size able voltage drop. Either run a thicker wire, or add another charger via a solar panel, or don't run the refrigerator on dc while on the road. The last one is my solution.

Rick

Tom and Shirley, you seem to have checked everything, but here's the way I'd do it.

With the trailer hooked to the tow vehicle and the engine running on the tow vehicle (nothing has to be moving, so the trailer top can be up), test the voltage on the trailer battery terminals with your voltmeter. If the tow vehicle is charging the battery, the voltage should read close to or above 14V. It should actually read very close to the reading you see if you put your voltmeter probes on the tow vehicle's battery terminals. The refrigerator does not have to be on for this test.

If the voltage is much lower at the trailer battery, then it is not being charged when you are towing. I'd suspect the fuse in the charging circuit in the tow vehicle is blown, or the relay (if one is in that circuit) is defective.

If the voltage is close on both batteries (and in the 14V range), turn the refrigerator on, powered by DC. Check the voltages again. If the trailer battery voltage is now below 13V, maybe 12.5V or less, the battery is being discharged by the current draw from the refrigerator. This would tell me you need a heavier wire, at least 10 gauge or maybe 8 gauge from the tow vehicle to the trailer plug in both the +12V line and the ground.

Try these checks and let us know what you find.

One other thing, if you stop for a significant amount of time on your trip, the refrigerator will be drawing current from the trailer battery only. It will kill a trailer battery FAST, and, the tow vehicle's alternator will not be able to recharge it, due to the other draws on the battery.

- Jack

Hilltool and JackandJane, thanks for the replies.
I can agree with you about the current draw. I will check that tomorrow with the TV and trailer hooked up. The wiring for the TV and the trailer are factory installed. I know the trailer is 10Ga and the TV I would say is also since it has factory trailer tow package. We have been traveling with the refg on DC since new with no problems. I will post my findings.

Tom (I suspect you are the one posting), my previous truck was a 2005 F150 with the trailer tow package, and, after a day's travel with the refrigerator on, the trailer battery would be low (but it would still raise the top). I got better results by adding an additional battery in the trailer, connected in parallel to double the capacity.

It really seemed to me the "killer" on the trailer's batteries was our stopping for lunch and occasional other stops for "leg exercise". I left the refrigerator on DC in those times, with the trailer top down.

I think, I probably should have raised the top during those stops and changed the refrigerator to gas; or, since raising the top also uses a lot of current, maybe I should have simply crawled into the trailer and turned the refrigerator off during the stops. It would not warm up much since it was full of cold food and the door is closed. Turning it back on would not generate a current "spike".

Note: DO NOT raise the top with the trailer connected and drawing power from the tow vehicle. The lift motor has such a large Amperage draw that if the battery is low and the refrigerator is on, it will almost surely blow your trailer charging fuse in the tow vehicle. It happened to me three times before I learned.

- Jack

I regularly raise the top while connected to the TV . But, not with reefer on. I've seen you , Jack, mention this before. Ofte if we stop for lunch I will raise the top and put the dog n there if we go into a restaurant and it is warm out. It is a good test for me to run sometime and see what the draw is on n the tv battery . With two group 27s it may be it never gets that far. In essence I assume I am running a three battery parrelel set up at that point.

hilltool said:

I regularly raise the top while connected to the TV . But, not with reefer on. I've seen you , Jack, mention this before. Ofte if we stop for lunch I will raise the top and put the dog n there if we go into a restaurant and it is warm out. It is a good test for me to run sometime and see what the draw is on n the tv battery . With two group 27s it may be it never gets that far. In essence I assume I am running a three battery parrelel set up at that point.

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That could be. In honesty, I've never blown the fuse since I put the extra battery in too, but I've tried to be careful to disconnect the trailer from the tow vehicle even so.

If you think about it, I believe the refrigerator pulls about 15+ Amps on DC power (that's only 15 x 12 = 180 Watts), but, think how many the lift motor needs, and, added to the refrigerator draw... If it can't get it from the trailer battery, it's going to look through the 30 Amp fuse to the alternator if connected and the engine is running. That fuse isn't going to stand up to that current spike.

It will be interesting to see how my solar panels help during travel. We have not been able to go camping yet due to various things - maybe late summer we'll get away.

- Jack

Rick and Jack: I did the test Jack posted.
The TV receptacle with the truck running was 14.47V.
The trailer battery read 13.70V.
The trailer battery hooked to the TV read 14.27V.
The trailer battery with refg running and hooked to the V read 13.64V.

Yup, TV not keeping up with refg running. I then sprayed plug and receptacle with electric contact cleaner. I then dug into one of my old tool boxes and got an ignition file. (More mature readers might remember ignition tools. The file was used to clean up points) I used the file to clean up the plug contacts. Hooked things back up and with the refg on DC and the truck running I got 14.24 on the trailer battery.

Bad contacts will get to you every time. I do like the idea of adding a second battery. We will look into doing that……and keep the plug and receptacle cleaned.

Thanks for your help.
Tom

windy hill said:

Rick and Jack: I did the test Jack posted.
The TV receptacle with the truck running was 14.47V.
The trailer battery read 13.70V.
The trailer battery hooked to the TV read 14.27V.
The trailer battery with refg running and hooked to the V read 13.64V.

Yup, TV not keeping up with refg running. I then sprayed plug and receptacle with electric contact cleaner. I then dug into one of my old tool boxes and got an ignition file. (More mature readers might remember ignition tools. The file was used to clean up points) I used the file to clean up the plug contacts. Hooked things back up and with the refg on DC and the truck running I got 14.24 on the trailer battery.

Bad contacts will get to you every time. I do like the idea of adding a second battery. We will look into doing that……and keep the plug and receptacle cleaned.

Thanks for your help.
Tom

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And thanks for your responses Tom, as there are several of us that have had the same experience. I had the same problems with a single battery in a 21T three years ago throughout Alaska and Canada, and I had the same problems with our 27T with dual batteries last year on an extended trip.

Now I have the problem. TV alternator is putting out around 13.8 at truck battery AND at receptacle at back of truck. But, hooked up, the trailer battery is not getting the charge- i"m at 12.55 which is up a bit from where it was after driving 6 hours the other day- but I've had a solar trickle charge on it for about a day now. 20 watt panel. Sure but SLOW. Anybody know what color the charging line is inside the battery box? Where does it connect? I am going to mimic Tom's contact cleaning but after the plug contacts I'd like to clean up up the rest of it------I'm just not sure where to clean. I'm assuming if I have power at the receptacle I dont have a blown fuse or popped breaker coming back from the alternator-----though Im not sure why I'm not pulling more amps from the alternator. I also have a bad cell in the truck battery so you would think the regulator would be allowing maximum voltage to the truck battery-which is around 12.3.

Rick

It should be the black wire from the trailer cord to the terminal strip.

Here is a link to a wiring diagram that will work on your trailer:
http://www.hilotrailerforum.com/f51/hi-lo-2306-primary-wiring-116/

Rich- thanks for the wiring diagram link. There IS a black wire, it seems, running over to one of two, from what I can tell, 30 amp breakers(?) mounted on side of battery box. I looked for little re-set button but do not see one. The post is pretty corroded and turns when I try to loosen the nut for cleaning. So- maybe it should be replaced? Where do you get those (breakers)?

Thanks- Rick

An auto supply store or RV shop should have them. Yours are auto reset so there are no buttons. They should be 30 amp.