Battery charge line while flat towing Gladiator

[Andy29847]

So the solution is?

There are a number of solutions covered in the thread listed above and again here:

https://www.jlwranglerforums.com/fo...flatlining-when-flat-towing.15523/post-378299

My Jeep is wired for lights with a Curt harness. I towed it for thousands of miles this summer without issue. My batteries were near new, I do not normally travel more than 400 miles a day, and I seldom travel at night.



If I thought that the LED light sensor would be a problem for me, I would pull out the Curt harness and install a set of extra taillights that wire straight to the camper trailer plug. Something like this:

RedRock Jeep Wrangler Wireless Magnetic Towing Lights with Storage Case U5558 (Universal; Some Adaptation May Be Required) - Free Shipping (extremeterrain.com)

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[Wildtoad]

I flat tow our Gladiator behind our RV. Anyone installed a charge line on their truck?

Couple of things. My Newmar gasser mh doesn’t have power to the charge pin. None of their gas models do. Your mh may be different. When required owners “fix” it.

I use a NSA Ready Brake setup between the mh and the Gladiator. No power to the Jeep required. No need for a charge line.

I have the tail lights powered and controlled from the mh. My setup uses a Roadmaster wiring kit that includes diodes to isolate the connections from the jeeps electrical system. Works great.

 

[Gezer]

My first vehicle with all this crazy electrics and such. Seem to learn something new here every day. Of course at my age I already forgot a load of stuff.

 

[Kevin_D]

I flat tow our Gladiator behind our RV. Anyone installed a charge line on their truck?

I use a charge line on mine.
I have the Brake Buddy braking system, and it'll run the battery dead without a charge line.
I also use wireless tail lights modified to use the Jeep's +12V instead of the light's batteries.

Kevin

 

[RubiCrusHehr]

I use a charge line on mine.
I have the Brake Buddy braking system, and it'll run the battery dead without a charge line.
I also use wireless tail lights modified to use the Jeep's +12V instead of the light's batteries.

Kevin

Ok I know where to get the 12v from the RV but how do you set that charge line. Do you run 12v direct to the battery ?? Do you have to use something special to protect the circuitry ??

 

[tcopeland]

I use a fuse in-line and a diode. Run from the 6 point connection to the battery.

 

[RubiCrusHehr]

I use a fuse in-line and a diode. Run from the 6 point connection to the battery.

Thank you !! How many amps for the fuse ?? And wire grade ?? Picture of your setup would be great

 

[PaulW]

Understand the use of a diode on the charge line. But really both batteries are at the same state of charge when you turn off the RV/Truck which means there will no current flow either way. Of course battery condition varies with time and current flow it a possibility.
I done use a diode, but its use is ok.
With a proper setup for the Gladiator there should be no parasitic battery drain when it is powered off.

 

[sharpsicle]

Understand the use of a diode on the charge line. But really both batteries are at the same state of charge when you turn off the RV/Truck which means there will no current flow either way. Of course battery condition varies with time and current flow it a possibility.
I done use a diode, but its use is ok.
With a proper setup for the Gladiator there should be no parasitic battery drain when it is powered off.

I don't think you quite understand the diode bit. It's to ensure that the RV charges the Gladiator, and at the same time helps ensure that the RV does not accidentally discharge the Gladiator. Helps ensure that a problem with the RV doesn't kill the Gladiator, that's all.

 

[ShadowsPapa]

But really both batteries are at the same state of charge when you turn off the RV/Truck which means there will no current flow either way

Gee, if that were the case, then no Jeep owner could ever possibly say that the main battery killed the aux or that the aux battery killed the main/crank battery.
You just blew all of those complaints away, since you say it's not possible and all batteries are always at the same state of charge.

they may experience the **same voltage while the tow vehicle is running, but they won't be at the same state of charge or even health.

(** not totally as there will be voltage drop across the line from the towing vehicle to the towed vehicle. IF the RV/tow vehicle runs at 13.8 volts the Jeep behind it will likely see less. And if the tow vehicle doesn't run as high a voltage as the Jeep batteries need, they may never reach full SoC)

 

[Kevin_D]

Ok I know where to get the 12v from the RV but how do you set that charge line. Do you run 12v direct to the battery ?? Do you have to use something special to protect the circuitry ??

I didn’t use a diode (a silicon diode will have a 7/10V drop across it, thus affecting the charge on the Jeep battery. To do it right, you should use a battery isolator that puts diodes on both batteries,) just ran the RV +12V to the Jeep battery through a 30A fuse (I’m using 10 ga. wire.)
If I’m going to park for any length of time (more than a meal stop) I unplug the Jeep from the coach.

Kevin

 

[ShadowsPapa]

I didn’t use a diode (a silicon diode will have a 7/10V drop across it, thus affecting the charge on the Jeep battery. To do it right, you should use a battery isolator that puts diodes on both batteries,) just ran the RV +12V to the Jeep battery through a 30A fuse (I’m using 10 ga. wire.)
If I’m going to park for any length of time (more than a meal stop) I unplug the Jeep from the coach.

Kevin

So use a different diode. The diodes on the shelves of my alternator parts only have a 1 volt drop. They'll handle some heavy amperage. One I'm thinking of will handle over 35 amps with a 1 volt drop.
I've likely got some with a lower voltage drop.

 

[Kevin_D]

So use a different diode. The diodes on the shelves of my alternator parts only have a 1 volt drop. They'll handle some heavy amperage. One I'm thinking of will handle over 35 amps with a 1 volt drop.
I've likely got some with a lower voltage drop.

7/10 as in 0.7V
A typical silicon high-power diode has that voltage drop. Unless you can monitor the voltage for charging directly at the battery, and not before the diode (as it would be with a toad,) the Jeep battery won't achieve a full charge: it'll always be 0.7V low.

Kevin

 

[GAJeff]

I have been flat towing my JT for over a year with no issues. I opted to install the cool tech harness, yes I had to splice but believe it is the best as you flip the switch when towing and isolates the rear led tail lights from the jeep eliminating any draw on the jeep electrical system. Never had any issues with dead battery, and have many hours of night driving racked up.

https://www.cooltechllc.com/2018-jeep-wrangler-jl/107-jl-tow-harness-kit.html

 

[ShadowsPapa]

7/10 as in 0.7V
A typical silicon high-power diode has that voltage drop. Unless you can monitor the voltage for charging directly at the battery, and not before the diode (as it would be with a toad,) the Jeep battery won't achieve a full charge: it'll always be 0.7V low.

Kevin

If the tow vehicle is running 14.0 system voltage, then at the Jeep it could be 12.8-13.0 volts.
That's more than adequate. We're not trying to charge a battery, we're merely preventing it from being discharged. Our Jeeps run at 13 volts or even lower if the batteries are full, so as long as the battery health is ok, and you are running at least battery voltage back to the Jeep, you will be preventing discharge.
The idea isn't charge the batteries - it's to prevent discharge.
I was driving mine a couple of nights ago, lights on, heat on, voltage running 12.9-13.0 volts.
If there's a draw on the Jeep it will pull the voltage of the tow vehicle down, regulation will keep it up, so there's no issue.
I see no problem.
And since some folks out there seem to run diodes, it's apparently not a problem.
Knowing charging systems - it won't be.

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