Need advice for Jeep Wrangler toad and Precept 35S

[NickM]

Between E-Trailers, Craigslist and eBay I managed to save somewhere north of $1500 on the installation but it is still a work-in-progress as I need to resolve the battery drain problem caused by the brake system. Almost done eating this elephant

[NickM]

Swapped my 2 door Wrangler JK to a 4 door JKU this week so had to review the mods needed to make it towable.

I mostly followed @SteveL's instructions and the JK towed well since January 2017. On our last trip a few weeks ago to Michigan I had issues with the Wrangler battery being dead at the end of a 6 hour day, and this is with a charge line from the MH to the Wrangler.

The house batteries would also be dead at the end of the day, how could this happen?

Installed new Duracell AGM batteries during our last trip but the Wrangler battery is still running down and I'm pretty sure it's not the auxiliary brake causing this problem.

I received my Blue Ox baseplate yesterday and the wiring kit from eTrailer will be here in a few days so I'll be duplicating my original install next week.

I'm looking for ideas as to why the Wrangler battery runs down even with the charging line. Checked Wrangler voltage with MH engine running and got 14.2, engine off 13.2 so I know it is charging while in the parking lot.

[hawkster]

Hmm. Last year I towed a jk with no charging line. Setup blue ox baseplate, trailer mate Jeep wiring harness thru 7 pin to 4 pin adapter. Blue ox Patriot brake controller that used 12v from Jeep while underway. Instructions said to start Jeep at end of the day for a few minutes to charge battery. No problems.

[NickM]

@Hawkster

I believe on my next trip in September I will start the Wrangler at every break in the trip. We usually try to stop every 2 hours or so just to get up, stretch and walk around.

I'm thinking something is draining my house batteries and the wrangler battery via the charge line so there is an issue to work through.

[cabinetmaker]

We tow a jk Rubicon. Be sure the auxiliary brakes are not set too sensitive that the brake lights are staying on.

It’s a good idea to remove the fuse for the brake lights while towing and just run the auxiliary lights from the motorhome.

I remove my key from the ignition so I know I remembered to turn it off.

Never had a problem with the battery.

[NickM]

I have the RVI2 Brake set for light sensitivity. I really don't think the aux brake is draining my battery. I used a Curt wiring kit with diodes so that the MH and Wrangler lights work together, never had a problem until 2 weeks ago.

My next trip I will remove the fuse in my charging line to isolate the Wrangler battery from the MH. I really wish I could defeat the steering lock so I don't have to have the ignition on.

[cabinetmaker]

Originally Posted by NickM

I have the RVI2 Brake set for light sensitivity. I really don't think the aux brake is draining my battery. I used a Curt wiring kit with diodes so that the MH and Wrangler lights work together, never had a problem until 2 weeks ago.

My next trip I will remove the fuse in my charging line to isolate the Wrangler battery from the MH. I really wish I could defeat the steering lock so I don't have to have the ignition on.

Our Jeep doesn’t have a steering lock. Not sure when they discontinued that but my 2018 JK Rubicon Recon you can just remove the key and lock it up when towing.

I would think the ignition on could cause your problem but you said it just started so who am I to know.

[hawkster]

Didn't think to mention that. My Jeep also had no steering lock. It was a 2015.

[Dustdevil]

Assuming you are removing fuses as discussed earlier, that would rule out parasitic draw from the ignition and on-board computer of the Jeep toad. That could be significant. If you are leaving those fuses in, or not bypassing, that would certainly draw down the battery of the Jeep.

The fact that both Jeep and Coach batteries are depleting tells me that your power consumption, whatever it is, is significantly greater than the motorhome alternator can keep up with. That may mean it's a short circuit somewhere. This, of course, assumes that the motorhome alternator charges the coach batteries while traveling. This is corroborated with your test results of higher voltage while the motorhome engine is running vs when it's stopped. The short circuit could also be at the motorhome end, unless you installed the diodes in that charge line.

[NickM]

Originally Posted by Dustdevil

Assuming you are removing fuses as discussed earlier, that would rule out parasitic draw from the ignition and on-board computer of the Jeep toad. That could be significant. If you are leaving those fuses in, or not bypassing, that would certainly draw down the battery of the Jeep.

Up until this point I have not removed any Wrangler fuses. I figured it was less of an issue to have a full time charging line, protected by 10 amp fuse, no blocking diode

The fact that both Jeep and Coach batteries are depleting tells me that your power consumption, whatever it is, is significantly greater than the motorhome alternator can keep up with. That may mean it's a short circuit somewhere. This, of course, assumes that the motorhome alternator charges the coach batteries while traveling. This is corroborated with your test results of higher voltage while the motorhome engine is running vs when it's stopped. The short circuit could also be at the motorhome end, unless you installed the diodes in that charge line.

Therein lies my problem. What in the world can be draining the coach batteries while driving? At one fuel stop I didn't have enough house battery to start the generator.

Yesterday I checked the generator panel which shows two bars out of the normal three bars for battery. I'm assuming this is strictly a relative voltage indication.

The coach battery check lights up all the leds when I press the Batt button, again, another relative battery indicator.

I'm preparing my new-to-me Wrangler Unlimited for towing over the next few days and will duplicate the setup I had in my original Wrangler. However, I will likely add a blocking diode to the charging line along with a fuse but I will not install the fuse for out first day of towing to isolate the Wrangler as a problem source. I plan to stop every 2 to 3 hours and start the Wrangler.

[tie-dye guy]

We have been pulling a 2015 Wrangler with the mopar wiring harness to operate lights and have never had power issues with pulling. Have you checked to make sure you have not having issues when not towing also? If you are still having issues when not pulling the Jeep, then your problem is entirely in the coach and not with the Jeep or connection to it.

[rkelley712]

have a 2020 jayco 31ul and a 2017 grand cherokee trailhawk with a ready brute elite II towbar and a blue ox baseplate installed by the dealer...and one baseplate came loose during a tow. After removing bumper after accident found support plates had not been installed to the frame....uggggh