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Old 12-19-2013, 03:12 PM   #15
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Originally Posted by Wazbro View Post
I believe that when the TV battery is fully charged, getting a charge rate of more then 1 amp to the trailer would be optimistic on most stock vehicles.

The system was only designed to keep a backup battery for a breakaway switch for electric breaks charged, NOT recharge a battery for a TT. That's not to say that it shouldn't be able to keep the battery charged and power the 12v circuit board in the fridge, that much should be easy.
I typically see around 8-10 amps with stock wiring if the trailer battery is significantly discharged.

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Old 12-19-2013, 03:13 PM   #16
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Originally Posted by Skater View Post
Probably true, but - if I understood the conclusions above correctly - getting more power (say 10 to 20 amps) to the camper for actual charging purposes shouldn't be too much harder than running heavy wires (appropriately fused) to the connector both on the tow vehicle and the trailer. Did I follow that conclusion correctly?
Many threads on this. I have 8 gauge wire on my pickup and 6 gauge wire on my Suburban. It does make a difference.

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Old 12-19-2013, 05:40 PM   #17
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The TV computer may have to be programmed to energize the charge line when the engine is running.
Your dealer should be able to determine this.
Or you could check the proper pin on the 7 pin plug with a VOM.
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Old 12-22-2013, 03:09 PM   #18
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Kyler, the 10 gauge, 30 amp wire to the converter panel is from the trailer batteries or the shore power receptacle. 10 AWG Romex is orange (30 amp at 120 v.), 12 AWG is yellow (20 amp), 14 AWG is white (15 amp0. I think the wire to the trailer batteries is 6 or 8 AWG and may be black, but I haven't looked in a while. Those color codes are fairly recent, so your older trailer may have different colors. The charge line from the tow vehicle will be a higher gauge number (smaller wire; probably 16 to 20 gauge) and the conductor inside the cable could be any number of colors, though black or red are most likely. A heavier gauge wire from the tow vehicle would be braided so it could bend, very expensive and very thick. You would need a very heavy duty alternator to supply enough power to it. It is meant to maintain trailer battery charge so that the fridge, propane detector and a few other items that use little energy can run. The brakes and trailer lights are energized through different wires in the harness directly from the tow vehicle lights, turn signals, brake lights and brakes.

The quickest way to charge the batteries is with shore power.

Your problem may be the trailer batteries are not holding a charge and need to be replaced.

You may have left already on your Christmas trip and I hope you've solved the problem.


The Airstream is sold; a 2016 Nash 24M replaced it.
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Old 12-22-2013, 04:53 PM   #19
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All modern fords have a relay on the charge line which disconnects the charge from the trailer to prevent fully discharging the vehicles battery while not running.
With that being said... many models come from the factory with the charge wire disconnected from the relay near the fuse block under the hood.
Check for +12v at the pin St the 7way with key on then off. If no power either way, you'll have to activate the charge line your self.
This is done intentionally as to prevent corrosion from leaking voltage when wet especially salty and wet.
I'll bet you'll charge up just fine.
My Excursion can fully charge 4 coach batteries in 300 highway miles.
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Old 12-23-2013, 09:03 PM   #20
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OK, now I have some experience to report...

1. The wiring diagram shows that pin 1 (+12V) of the 7-way connector goes directly (through circuit breakers) to my battery.

2. I verified #1 by disconnecting the plug and poking a circuit tester in it with the battery in "store" mode. It lit.

3. Last night I ran the furnace and drained the battery quite a bit. Driving a few hours today has charged it well.

4. I think my two batteries are rated for about 80 Amp-hours each. If I use them to 50% that's about 80 Amp-hours to recharge. I'd be delighted to get 20A from the TV. I think I'm fairly. It's quite usable.

5. I'm parked in Jennings, LA tonight. Heading to Houston tomorrow. Good so far.

Thanks, all!


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