Troubleshooting Towed Battery Still Dying After Installing Charge Line Kit

Updated 09/09/2024 | Published 08/31/2024

Question:

Using the Roadmaster Battery Charge Line Kit for Towed Vehicles. I have 14.5vdc coming from my RV, but when I connect it to the breaker it s to 12vdc and my battery on tow dies. Do I have the breaker backward, or is it bad. Gold terminal is from RV, silver to towed battery post. Thank you

asked by: Brad B

Expert Reply:

Hey Brad, thanks for reaching out!

It sounds like you have the Roadmaster Battery Charge Line Kit # RM-156-25 installed correctly (according to the linked photo from the instructions), so I'm wondering if you have something pulling too much power on your towed vehicle so it's still depleting your battery.

Have you gone through your vehicle owner's manual and followed all of the steps for prepping your vehicle for flat towing? I recommend double checking on that first.

expert reply by: Jon G

Battery Charge Line Kit Wiring Diagram
(click to enlarge)

Brad

9/3/2024

Hi Jon, I'll double check owners manual to make sure I'm not missing something. My tow is a 2013 ford fusion hybrid, if you have any suggestions. I did order another charge line kit just in case breaker is faulty. I'm also going to reverse the connections just to see. I head home on Saturday, will keep you posted. Thank you

Brad

9/6/2024

Hi Jon, more information for you. I found with Ignition in position l or ll charge voltage is absent. However in position lll which is on but engine not started the charge voltage makes it across the breaker. I'm heading home tomorrow approx 300 miles, we try towing with Ignition in this position and see what happens. Let me know your thoughts Thank you Brad

Jon G.

9/9/2024

@Brad Sorry, I was out of town over the weekend - I hope your trip turned out okay! As long as you're following the instructions for flat towing in the manual for your Fusion then you'll be okay. Sometimes the instructions are really simple but other times there is a multi-step process to make sure everything still functions properly which is why we defer to the manual.

Brad

9/9/2024

@JonG Hi Jon, keeping the car Ignition in position lll without engine running worked. Trip home took 5 hours and car started up when I got home. Appreciate your help and responses. Have a great day.

Jon G.

9/9/2024

@Brad Glad to hear it! Thanks for the feedback!