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Battery Isolation Relay For Travel Trailer
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=20351		 Page 1 of 1
Author:  Wobbly [ Wed May 02, 2007 11:15 pm ]
Post subject:  Battery Isolation Relay For Travel Trailer
Is there a relay in the CRD that isolates the starting battery from the trailer electrical system when the CRD alternator isn't charging? If not, loads in the trailer might deplete the CRD's starting battery. My trailer has a manual switch, but it would be nice if the CRD cut off power automatically.

Anyone know the outpout of the CRD alternator?

Thanks,


Wobbly
Author:  Zonie [ Thu May 03, 2007 12:36 am ]
Post subject: 
I don't have the technical knowledge, but in 5 days of camping, I found that when the Jeep was connected to the trailer, the battery was weaker in the morning. The engine turned over really slowly.
Author:  Joe Romas [ Thu May 03, 2007 9:56 am ]
Post subject: 
I have the add on MOPAR factory harness and suplementry cable installed on my 96 and there is a constant 12 volts on pin 4 of the round trailer connector. There are relays in the towing harness mounted in the right rear fender well but they are for lights only as far as I can tell. There's a fuse in the power distribution panel with a wire attatched under the hood but my cables came with a seperate cable and fuse so I used it. I was unable to find where the factory installed "trailer tow" wire termineated inside the jeep.

As a side note on a trailer group I subscribe to this question is asked often and it seems the majority of vehicles, if not all, have the 12 volts to the trailer wired through a fuse directly to the battery. So with the refrigerator running on 12 volts your TV (tow vehicle) battery will be discharged in a few hours. Also it seems that your trailer battery will not be suffeciently charged by the TV alternator. There was a recent thread here about the output current of the alternator but I don't recall exactly what it was.
Author:  Wobbly [ Thu May 03, 2007 10:48 am ]
Post subject: 
I was thinking of adding auxiliary charging cables with Meltric connectors such as described here:
http://www.damouth.com/RVStuff/TrCharge.shtml
and adding an Intellitec Isolation Relay Delay and isolation relay:
http://www.intellitec.com/PDF/5300362.100.pdf
Author:  Joe Romas [ Thu May 03, 2007 11:04 am ]
Post subject: 
Wobbly wrote:
I was thinking of adding an auxiliary charging cables with Meltric connectors such as described here:
http://www.damouth.com/RVStuff/TrCharge.shtml
and adding an Intellitec Isolation Relay Delay and isolation relay:
http://www.intellitec.com/PDF/5300362.100.pdf


Lots of suggestions there :shock: I guess it depends on how much you use your trailer. For me just adding the relay and heavier wiring into the standard 7 pin connector would suffice. I'm a firm beliver in the KISS philosophy :D
Author:  Wobbly [ Thu May 03, 2007 11:31 am ]
Post subject: 
After looking at this thread: http://groups.google.com/group/rec.outd ... 9f4f271429

I see that the problem isn't just the high resistance of the standard 7-wire harness charging wire, it's also about the need to rapidly and completely charge the trailer battery using a "smart" battery charger.

Installing an inverter in the truck with a 120 VAC line with disconnect to a smart converter/charger seems like the ultimate solution. Costs a few hundred bucks, though.
Author:  Cowcatcher [ Thu May 03, 2007 12:10 pm ]
Post subject: 
Haven't towed with the Jeep yet but my solution on my Chevy P/U was to only plug the trailer in while driving. Sort of a 5 digit relay.
Author:  Zonie [ Thu May 03, 2007 12:16 pm ]
Post subject: 
The 5 digit relay worked for me.... When on the road with minimal tools and technical knowledge
it seemed like a simple solution.
Author:  Stan Wright [ Thu May 03, 2007 5:19 pm ]
Post subject: 
The factory towing package supplies 12V to the trailer connector via relay only when the key is on.

The output of the CRD alternator seems to be a closely guarded secret.
Author:  ed. [ Thu May 03, 2007 5:22 pm ]
Post subject: 
You could use an isolator such as the Traxide unit.
www.Traxide.com.au so it will charge the trailer's battery when the car is running and disconnect it when the car is off.
Author:  Joe Romas [ Thu May 03, 2007 7:41 pm ]
Post subject: 
Stan Wright wrote:
The factory towing package supplies 12V to the trailer connector via relay only when the key is on.

The output of the CRD alternator seems to be a closely guarded secret.


I searched the wiring pages of my FSM relating to trailer-tow, section 8W-54 pages 1 through 6, and could not verify this. I then went out and metered mine and there was 12 volts all the time on pin 4. I installed per directions both the MOPAR "trailer tow harness and complementry harness. Zonie's post above would also verify the connection is not switched :?:
Author:  Wobbly [ Thu May 03, 2007 8:16 pm ]
Post subject: 
ed. wrote:
You could use an isolator such as the Traxide unit.
www.Traxide.com.au so it will charge the trailer's battery when the car is running and disconnect it when the car is off.


Looks like a nice unit. How many lobsters do they want for one?

Wobbly
Author:  spoonplugger1 [ Thu May 03, 2007 8:21 pm ]
Post subject: 
I always unplug all trailers from the rig once I'm not road driving, especially boat trailers before the boat goes in the water. Just second nature now, unhook at night, hook up after starting the rig in the morning.
Author:  Stan Wright [ Thu May 03, 2007 8:34 pm ]
Post subject: 
Joe Romas wrote:
I then went out and metered mine and there was 12 volts all the time on pin 4.


That's odd. Mine is switched. Page 8W-54-5 in the service manual shows the relay...Relay - Trailer Tow. Here is a link to that page: http://liberty.eurekaboy.com/8w-54-5.jpg

I even verified it when I installed my backup lights: http://liberty.eurekaboy.com/reverselights.htm

Maybe some are wired differently?
Author:  Marlon_JBT [ Thu May 03, 2007 8:56 pm ]
Post subject: 
I believe the alternator is the same one (or at least it looks the same) as the 3.7L alternator... which is 130A.
Author:  Joe Romas [ Fri May 04, 2007 6:57 am ]
Post subject: 
Stan Wright wrote:
Maybe some are wired differently?


That's what I suspect. That relay is listed as being in the right rear quarter panel and that bundle is part of the tow harness. On a post a while back the person discribed what he had as being more like solid state relays in his bundle but mine feel like relays inside the bundle. If I get too curious I'll open the bundle up.
Author:  LanduytG [ Fri May 04, 2007 8:31 am ]
Post subject: 
ed. wrote:
You could use an isolator such as the Traxide unit.
www.Traxide.com.au so it will charge the trailer's battery when the car is running and disconnect it when the car is off.


You don't want to use and isolator because the trailer battery will never get a full charge. The relay separtor it the way to go. We install these all the time on class 8 over the road trucks to charge the aux batteries for hotel services. The key can be on on the truck but unless the truck is running and charging the relay will not close. These are easy to install and give no problems. One word of cation though and thats the wire size going to the trailer. You want at least a #10 to handle the current. I don't know if the CRD is that big but pickups are.



Greg
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