Why Would Vehicle with Charge Line Kit Cause Dead Battery After Year When it was Working

Updated 02/03/2026 | Published 01/29/2026

Products Featured in This Question

Curt RVi Series Towed Battery Charger+ for Flat Towing

(9)

$199.71

Towed Vehicle Battery Charge Line Kit for Demco Air Force One and Stay-IN-Play Duo Braking Systems

(217)

$26.29

Question:

I have a 2022 Wrangler set up with the Demco stay-in play braking system, roadmaster brake light switch 751490, roadmaster brake-lite-relay, curt wiring harness C96JR, and I installed a Demco battery charge line kit DM66VR. I have been having dead battery issues after Flat towing long distances with over night stays. Everything was ok the 1st 2 1/2 years. Then the dead battery issue started. I had a 2018 Wrankler JK with the same set up and towed 4 years no problem. All above set ups were with etrailers help. Question Would the curt RV174FR do a better job?

asked by: Michael R

Expert Reply:

Hey Michael, it actually sounds like the battery in your Wrangler is the issue. If it was holding a charge just fine when you first started towing and nothing has changed yet it's now dead when you stop that to me would indicate the battery is on it's last leg and needs to be replaced or the charge wire you are using has maybe lost it's connection and it's stopped charging. I would check the pins of the trailer wiring connectors for corrosion and clean as needed as well as make sure the wire didn't get cut.

The charge that the part # RV174FR would provide would be better than the # DM66VR that you have now but I don't believe this is for sure the solution to what you have going on.

If you have a circuit tester you might test the charge line to make sure it has current still.

expert reply by: Jameson C

Michael R.

1/30/2026

Sorry I forgot to mention in my previous post that I replaced the Battery in Sept. 2024 so it has been a little over a year on this one, The original lasted Approx. 2 1/2 years. I found on the jeep forum that there is another battery under the main battery for the stupid start/stop add on. I will replace both, check the charge line connection, and keep the main battery as back-up. Thanks for your reply.

Jameson C.

2/2/2026

@MichaelR Good to know! I always wondered how the start stop was going to work on a vehicle with a weak battery. I couldn't imagine having a weak battery that you just jumped and having it kick off when you pull up to an intersection.

Tim S.

2/3/2026

Hi Michael, I had the exact same issue with my 2024 Jeep Gladiator with LED lights. After trouble shooting I found the following: 1. Jeeps with LED lights (possibly other configurations, too) turn on the jeep computer every time the tail lights are activated, thus greatly increasing the current draw on the battery. The computer can "wake up" and stay on for 3-6 mins (so I'm told). 2. The fuse in my rig (a class A) that powers the 12V charge line had blown. Thus my jeep was getting no charge from the rig. Note that all the other lights on the Jeep in tow mode worked because each line had it's own fuse. So checking the lights each time we towed did not catch this issue. 3. The screws on my blue ox cable connector had come loose, thus giving me intermittent connections across all the wires. 4. My main battery on the jeep was bad, probably because after the above issues occurred the jeep's battery was drained too many times and thus damaged. I can't say what specifically blew the rig's fuse, but no doubt the above issues probably contributed. I also noticed that the original installers had connected my rig's charge line directly to the battery with a fuse near the battery. This fuse had not blown. I decided to install the Curt RVi to deal with the differences between the AGM batteries of the Jeep verses the standard batteries of the rig . (Yes, there are actually two batteries in the jeep - the 2nd smaller one is below the large one and apparently needed for the Auto Stop-Start system.) After replacing the jeep's bad main battery, blown fuse in rig, retightening wire screws on the cable (both ends), and installing the RVi I've had no issues, even on multi-day towing trips where we did not disconnect. I also like the RVi system because with a quick check of the unit's lights I can see that the Jeep battery and the rig's charge line are both active and at the correct voltage. This gives me peace of mind. Good luck.