Roadmaster Battery Charge Line Kit for Motorhomes

Roadmaster Battery Charge Line Kit for Motorhomes

Item # RM-156-75

lowest price pledge


Our Price: $33.11

You Save: 26%
Accessories and Parts

Orders above $99 qualify for Free Shipping

Shipping Weight: 1.2 lbs

In Stock, Ships Today
Roadmaster Tow Bar Wiring - RM-156-75
zoom in icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.
Please enter a valid email address.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

pop out icon replay 360 icon
horizontal rotate icon

Product Images

In Use/Installed

  • Tow Bar Wiring
  • Battery Charge Line Kit
  • Roadmaster
This charge line connects to the battery in your RV to allow up to 15 amps to be transferred to your towed vehicle's battery during towing. Requires RM-156-25 be installed in towed car. Call 800-298-8924 to order Roadmaster accessories and parts part number RM-156-75 or order online at Free expert support on all Roadmaster products. Guaranteed Lowest Price and Fastest Shipping for Roadmaster Battery Charge Line Kit for Motorhomes. Accessories and Parts reviews from real customers.

  • All Info
  • Reviews (9)
  • Q & A (60)
  • Videos (8)
  • Photos
  • Why etrailer?

Roadmaster Accessories and Parts - RM-156-75

This charge line connects to the battery in your RV to allow up to 15 amps to be transferred to your towed vehicle's battery during towing. Requires RM-156-25 be installed in towed car.


  • Allows power from your RV's battery to be used to maintain the charge of your towed vehicle's battery while the car is being towed
    • Transfers just 15 amps to avoid overcharging the car's battery
  • Connects battery to 6-way or 7-way plug at the rear of your RV
    • Requires Roadmaster's vehicle battery line (RM-156-25 - sold separately) if no charge line is present in your towed vehicle
  • Includes 12-guage wire, split wire loom, circuit breaker, and hardware
  • Made in the USA

156-75 Roadmaster Battery Charge Line Kit for Motorhomes

Video of Roadmaster Battery Charge Line Kit for Motorhomes

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Roadmaster Battery Charge Line Kit for Motor Homes Installation

Today we'll be having a look at the Roadmaster Battery Charge Line Kit for motor homes, part number RM-156-75. Okay, with our charge line all hooked up now, this will supply our vehicle that's being towed behind our motor home with 12 volts of power, so the battery in it won't run down while it's being flat-towed. Additionally, if we're hauling just a standard trailer, this will charge the breakaway battery on the trailer, so if the trailer we're to become unhooked, the breakaway battery will have sufficient amount of power to apply the brakes to slow the trailer and stop it safely. This breaker will keep us from having to worry about having to replace fuses on our charge line kit. If, for some reason, there'd become a short and the system would become overloaded, the breaker will flip open and will automatically reset once the problem has been corrected or the breaker has cooled off. It's a quick and simple installation, just one wire to hook up, running from the back of your 7-way connector or your 6-way, depending on the type of connector you're using. Attach it to your breaker then have one lead going to the positive terminal on your battery. Now that we've gone over some of the features, we'll show you how to get it installed.

We're going to use this red wire right here for the charge wire, so we'll strip off some of the insulation, and then we did our charge line, which is the red wire, that went into the terminal marked, AX, for auxiliary, and we'll slide this down. We'll clip it into place til it snaps. Now we'll tighten the wire to clamp up all the way, and we use a 10 millimeter socket and a phillip screwdriver here in order to snug this down the rest of the way. Okay with those snugged down, our 7-way is now securely mounted. All right, so we went ahead and routed our charge line to our vehicle's house battery. It's charged by the alternator so it will be good there.

We secured our wire up to existing wiring harnesses, making sure we kept it out of the way of any moving parts or sources of heat. If you follow a factory wiring harness, more than likely you'll be okay, so there's a wiring harness inside our frame rail. We just followed along that, securing it up with zip ties along the way. The wiring goes through this grommet into the compartment where our battery is stored. Now in our battery compartment here, on our RV, on our case it's behind the driver's side door, we're going to mount our circuit breaker near our battery. Right here, next to the right of our factory circuit breakers will be a great spot.

We'll just use the provided self-tapping screw and secure it in place. You'll see we have one in. We'll do one on the other side too. Now, the wire will need to connect to the auxiliary port on our breaker. That's the silver one.

It's also the top one in our case. I'll measure off how much we're going to need and cut off the excess. We'll strip off some of the insulation here and we'll crimp on one of our small ring terminals. Then we'll remove the nut and place it on. Reinstall the nut. Now in one of the ends of the wire, we just cut off we'll strip off some more insulation and attach the other small ring terminal to it, crimp it down and we'll attach it to the gold terminal on the bottom that's marked, BAT, for battery. We'll measure off how much we're going to need to attach the positive post on our battery, cut off the excess, strip back some insulation, make sure our large ring terminal will fit over there, which it will, stick over the wire and we'll crimp that one down. Before we connect that we're going to tighten down those 2 nuts with a 10 millimeter socket. All right, now we'll take off the wing nut on our positive battery terminal here, place on a ring terminal over the stud and reinstall the wing nut. We'll snug it on down with a pair of pliers. Okay, with that secure, our install is now complete. We'll show you how to test it. We're going to use a trailer simulator here, If you'd like to purchase one of these, you can find one on our website or you can just hook it up to your trailer. Open our door up here, we'll insert our 7-way plug, close the door on over. First thing we're going to check is make sure we have our charge line working on this. We'll flip our gage down here to battery charge and as you can see, we're getting about 12 volts. That means that's working. That completes our look at the RoadMaster Battery Charge Line Kit for motor homes, part number RM-156-75. .

Customer Reviews

Roadmaster Battery Charge Line Kit for Motorhomes - RM-156-75

Average Customer Rating:  4.9 out of 5 stars   (9 Customer Reviews)

This charge line connects to the battery in your RV to allow up to 15 amps to be transferred to your towed vehicle's battery during towing. Requires RM-156-25 be installed in towed car.

- RM-156-75

Would highly recommend using etrailer for any trailer accessories that are needed. Very friendly staff and shipping is fast and accurate on delivery. 656071

- RM-156-75

Very easy to install. Everything needed is included. 639335

- RM-156-75

Installed in my motorhome, works great easy to install following instructions provides. No more dead battery in the toad. 594360

- RM-156-75

Worked fine easy to install directions were good 594151

- RM-156-75

still n the box , did not use it . arrived after I went another route. 590022

- RM-156-75

Works as it is supposed to. 586150

- RM-156-75

Everything needed is in the box. 575335

- RM-156-75

The battery charged kit connected on to our motorhome to charge the battery of our jeep has worked excellent and the installation also was an excellent job we are very happy with our installation. 522735

- RM-156-75

This base plate was relatively easy to install (if you're handy and can follow written & video instructions), and is practically invisible when not being used for towing. Everyone at etrailer were helpful and knew exactly which parts were needed, even a year later when I asked about using the same base plate on a newer vehicle. The picture is just after install on my 2017 C-Max. 421005


Ask the Experts about this Roadmaster Accessories and Parts
Do you have a question about this Accessories and Part?

  • How to Keep a Flat Towed Vehicles Battery Charged
  • I do have a better option for you but the Tekonsha Two Stage 12 V DC Battery Charger part # 2024-07 is mainly used to charge a breakaway systems battery which is much smaller than the 12 volt battery you have on your toad. A better option for you would be to run a charge line kit like part # RM-156-25 from the tow vehicle to the toad. If you are towing the vehicle behind an RV than you would also most likely need a charge line kit for the RV like part # RM-156-75. I have attached an...
    view full answer...

  • Parts Needed to Flat Tow a 2018 Jeep Cherokee Trailhawk
  • Can you be more specific on if you are referring to the price of the parts or an installation? If it is the parts, there are a number needed and I'll be happy to let you know what they are if you need recommendations.
    view full answer...

  • Troubleshooting Battery Charge Line Kit on 2018 Jeep Cherokee
  • I can assume you are using the recommended Roadmaster Battery Charge Line Kits # RM-156-25 for towed vehicles and # RM-156-75 for motor homes. I've added links to installs of these kits for you to refer to so you can ensure your install followed the same process. If by "switched" or "unswitched" you are asking if the 12 volt circuit turns off when you turn off your RV, then it seems as if it is not switched. You will want to disconnect your 2018 Jeep Cherokee from your RV when you are...
    view full answer...

  • Is a Tow Vehicle Battery Charge Line Needed for Supplemental Braking System Like Stay-In-Play Duo?
  • When using any supplemental braking system on any vehicle, I recommend adding a charge line to the vehicle being towed. The Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25 is easy to install and simply gives that additional peace of mind that your TOAD will start without any issue once you get to your destination even when it has been a lengthy trip. This kit simply uses your wiring connection from your motorhome to maintain your vehicle battery so that it is never...
    view full answer...

  • Installing Roadmaster Battery Charge Line Kit on 2018 Jeep Cherokee
  • It sounds like you are referring to the Roadmaster Battery Charge Line Kit # RM-156-25 for your 2018 Jeep Cherokee. This kit allows you to connect your Jeep's battery to the 6-Way or 7-Way plug at the front of the vehicle so that up to 15 amps from the RV's battery can be used to maintain its charge while being towed. If no charge line is present in your RV, you will also need to add the Motor Home Charge Line Kit # RM-156-75. For the charge line kit, you will attach the included length...
    view full answer...

  • What Fuses Need to be Pulled to Flat Tow 2017 Honda Fit
  • I took a look at the online owner's manual for your 2017 Honda Fit EX. It starts off by stating that only the manual transmission models of the Honda Fit can be towed behind a motorhome with all four wheels on the ground. For extended towing (more than eight hours in one day) you will need to remove the 20 amp accessory power socket and 7.5 amp ACC fuses. These fuses are located in the interior fuse box. You will also want to remove the 15 amp back up fuse located in the engine compartment...
    view full answer...

  • Recommended Charge Line for Motorhome and Towed Vehicle Battery Connection
  • For your charge line, I recommend the Roadmaster Battery Charge Line Kit for Motor Homes # RM-156-75 and then for your towed vehicle # RM-156-25.
    view full answer...

  • Installing a Towed Vehicle Battery Switched Charging Line on 2016 Ford F53 Chassis Motorhome
  • For your 2016 Coachmen Mirada 35LS, to find a switched power line I recommend using a circuit tester like # 40376. Then you will use the Roadmaster Battery Charge Line Kit for Motorhomes # RM-156-75 with solenoid # TR118665 after the circuit breaker with the center post connected to your switched power line. This with make sure that power is only drawn from the motorhome when the ignition switch of your Coachmen is turned on. Then on the towed vehicle (toad) side you can use the Roadmaster...
    view full answer...

  • How to Avoid Battery Drain While Flat Towing a 2013 Honda CR-V
  • If the 7-way on your motorhome is a factory 7-way then the fuse will be in the fuse box and the legend on the box or in your owner's manual should tell you which cavity the 12 volt power will be. If it's an aftermarket 7-way it's possible the 7-way doesn't have a 12 volt circuit and you'll need to install a charge line on the motorhome using # RM-156-75. You'll also need the vehicle side in your 2013 Honda CR-V # RM-156-25. In addition, if you aren't already doing so according to...
    view full answer...

  • Recommended Charge Line for Toad Behind Motorhome
  • The battery of your 2015 GMC Yukon must be disconnected to protect your electronics when towing. If your supplemental braking system uses power, then I recommend the Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25 on your vehicle. If you don't have the charge line on your 7-way or 6-way of your motorhome, then I recommend # RM-156-75 for that charge line kit. To make disconnecting and reconnecting your Yukon battery easy, I recommend the Roadmaster Automatic Battery...
    view full answer...

  • Installing Battery Charge Line To Power Tow Vehicle
  • The Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25 and the Roadmaster Battery Charge Line Kit for Motor Homes # RM-156-75 will allow you to power your tow vehicle through a 6-way or 7-way wiring connection between vehicles. If you want a separate connector you can run a cord for that, but most people use the 12V pin or another unused pin and the 7 to 6-way cable to power their connection using a cord like the Roadmaster 7-Wire to 6-Wire Straight Cord Kit - 6-1/2' Long...
    view full answer...

  • Powering Blue Ox Braking Buddy on 2016 Ford F-150 that Cuts Off Power Supply When Flat-Towing
  • You can get around this feature of the Ford F-150 by installing a power outlet like # RM-9332 directly to your truck battery and plugging the braking system into it. To provide a maintenance charge to your battery and prevent the braking system from quickly draining it, you can also run a charge wire such as the Roadmaster Battery Charge Line Kit for Towed Vehicles, # RM-156-25. This kit maintains the battery charge in your towed vehicle during towing using the 6-way or 7-way plug at...
    view full answer...

  • Does Roadmaster Battery Charge Line Kit Connect Straight to Battery on Motorhome
  • The Roadmaster Battery Charge Line Kit for Motorhomes # RM-156-75 connects directly to the battery on your motorhome though it is wired through a circuit breaker, which comes with the kit. Please keep in mind you will need Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25 if the vehicle you are flat towing does not have a charge line.
    view full answer...

  • Comparing Roadmaster Battery Charge Line Kits
  • I took a look at the manual for the Roadmaster Battery Charge Line Kit for Motor Homes # RM-156-75 as well as the manual for the Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25. The kit for towed vehicles specifies 14 AWG wire while the kit for motor homes specifies 12 AWG and I recommend sticking to that gauge wire on both, particularly because it includes the wire with the kit. As far as the breaker terminals there is not a significance in color difference because...
    view full answer...

  • Installing Battery Charge Line After 7-way to 4-Way Brake Buddy Conversion Flat Towing 2015 Kia Soul
  • When using external lights like the Heavy Duty Magnetic Tow Lights - 20' Wiring Harness with 4-Way Flat Trailer Connector # TL21RK, you can run a separate wire for your battery charging connection. If you are using the Brake Buddy Stealth Supplemental Braking System - Proportional # HM39530 you will have the 4 way you referenced coming out of that harness. I recommend using the Roadmaster Battery Charge Line Kit for Motorhomes # RM-156-75 and the Roadmaster Battery Charge Line Kit for...
    view full answer...

  • How to Power Braking System with Battery Disconnected for Flat Towing a 2017 Ford Edge
  • If you are using a supplemental braking system like the Blue Ox Patriot II # BRK2016 in your 2017 Ford Edge flat towing setup then you can use the 12 Volt Outlet Kit # RM-9332 to supply power to it. Something that you may find useful if you plan on flat towing frequently is the Roadmaster Automatic Battery Disconnect with Switch # RM-766. It will disconnect your battery with the flip of a switch so that you do not need to have any tools on hand, plus it makes the process much quicker. If...
    view full answer...

  • Titan BrakeRite EHB Electric Over Hydraulic Actuator Will Not Work with 2017 Ford F-350
  • The issue you are having with the Titan BrakeRite EHB Electric-Hydraulic Actuator part # T4813100 or part # T4822500 is attributed to the lack of power on the 12 volt wire for the 7-way trailer connector. This is what powers the unit so if you don't have 12 volts here then the unit will not function properly. The 2017 Ford F-350 may only send power to the 12 volt power wire on the 7-way trailer connector when the vehicle is in drive therefore it would be best to bypass the 12 volt...
    view full answer...

  • Charge Line Kit for Flat Towing a 2017 Ford Explorer Instead of Disconnecting Battery
  • The reason many vehicles need the battery to be disconnected in order to flat tow it is to keep the battery from draining. Installing a charge line kit like # RM-156-25 on the vehicle and # RM-156-75 on the motorhome is another way to maintain the battery's charge. However, in some cases the manufacturer requires the battery to be disconnected in order to prevent specific features on the vehicle from operating once it's setup to be towed. In this instance you will need to disconnect...
    view full answer...

  • Does Fuse of 2014 Honda CR-V Have to Be Removed When Flat Towing Even With Charge Wire
  • Our # RM-156-75 which is used to charge a tow vehicle's battery when being flat towed wouldn't be enough to leave the fuse left in your 2014 Honda CR-V. Some of the depletion of the charge might be offset, but in the end you always have to go by what the manufacturer of the vehicle recommends.
    view full answer...

  • Does Mopar Wiring Kit Need to be Installed to Flat Tow a 2017 Jeep Cherokee Trailhawk
  • To the best of our knowledge the Mopar wiring is needed up to the 2019 model of the Jeep Cherokee. Unfortunately it looks like your dealer didn't know what they were talking about per the Jeep tech bulletin for the wiring kit 68321424AB, especially if it is in your owner's manual. If you don't already have equipment to flat tow your 2017 Cherokee Trailhawk then I recommend going with the Blue Ox Base Plate Kit # BX1136 along with the Alpha Tow Bar # BX7365 which is rated for up to 6,500...
    view full answer...

  • Installing the RoadMaster Transmitter # RM-9420 for Even Brake on a 2017 Ford F-150
  • If you use a circuit tester like part # 40376 you should be able to locate some wires behind or around your brake pedal and test them. If one gets hot only when your brake pedal is pressed then you can connect the RoadMaster Transmitter # RM-9420 to that. Otherwise your best bet would be to located the trailer brake controller connector and tap into the stop light switch that way. If you check up under your dash to the right of the steering wheel (basically behind that center panel)...
    view full answer...

  • Adding a Trailer Battery Charge Line to 4-Way Trailer Connector
  • To charge your trailer battery from your vehicle, I recommend the Roadmaster Battery Charge Line Kit # RM-156-75. This can be run to 5 way connection on each side like the Hopkins Endurance 5-Way Flat Trailer Wiring Kit - Vehicle and Trailer Ends - Ergonomic Design # HM47890. This will give you a clean connection of both sides to run to your battery terminals.
    view full answer...

  • Best Way to Keep Battery Charged on 2016 Jeep Wrangler While it's Being Flat Towed
  • Yes, you can wire a charge line from the back of the # RM-15267. The kit that includes everything you'll need, including a 15 amp circuit breaker, is part # RM-156-25. This will maintain the charge on your Jeep's battery but it will not actually charge a dead battery. I've linked a video of it being installed in a 2016 Jeep Wrangler Unlimited. In addition, if you need your RV to be wired to supply the power the kit is # RM-156-75. For a supplemental braking system I suggest the...
    view full answer...

  • How to Keep Battery From Draining While Flat Towing a 2016 Ram 1500
  • Since your 2016 Ram 1500 doesn't require the battery to be disconnected while it's being flat towed you can use a charge line to maintain its battery. The Roadmaster # RM-156-25 is what you will install in the Ram and # RM-156-75 will install in the RV.
    view full answer...

  • Vehicle and Motorhome 12V Charge Line Kits
  • You can use Roadmaster Battery Charge Line Kit for Towed Vehicles Item # RM-156-25 for your 2017 Jeep Wrangler Unlimited. If there is no charge line on your RV then you will also need the motorhome side kit # RM-156-75.
    view full answer...

  • Recommended Roadmaster Battery Charge Line Kit for Towed Vehicles Amperage Transfer at 12V
  • It is very normal for the 12V charge line on a vehicle to provide only the voltage that is being provided by the alternator that is not being used by the vehicle itself. The 3.5 volts is not normal but just 3.5 amps would be normal when the vehicle is running. If you want the full 12V power, then you will need to run the # RM-156-75 which will give you 12 gauge wire and allow you to transfer 15 amps to avoid overcharging your Jeep battery.
    view full answer...

  • Battery Charge Line Kit Recommendation for Flat Towing with RV Without 12 Volt Circuit Active
  • Since the 7-way of your tow vehicle does not have the 12 volt accessory circuit active you'll need the charge line kit from Roadmaster part # RM-156-75 installed on the tow vehicle to complete that and then on the towed vehicle you'd need the part # RM-156-25 and you'd be set. The fuses of your Fit will still need to be disconnected.
    view full answer...

  • Recommended Parts Needed to Flat Tow a 2015-2018 GMC Canyon or Chevy Colorado
  • The GMC Canyon and Chevrolet Colorado are practically the same vehicle with 2 different names. When it comes to flat towing they both have the same instructions and fits. For the 2015-2018 model years you can flat tow a 4WD but you cannot flat tow a 2WD. Whichever way you decide to go, make sure it is a 4WD so you can flat tow it. A complete flat towing setup includes a base plate kit, tow bar, safety cables, vehicle tow bar wiring, a supplemental braking system, and possibly a high-low...
    view full answer...

Do you have a question about this Accessories and Part?

  • Why

    At we guarantee:

  • Highest quality accessories and parts for the best price.

    Our Lowest Price Pledge ensures you will never overpay for the parts you need.
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate accessories and part information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Satisfaction Guarantee
    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Video by:
Joe V
Edited by:
Lindsey S
Installed by:
Jeff D
Expert Research:
Jameson C
Video by:
Joshua S
Video Edited:
Jacob T
Video by:
Kathleen M
Video by:
Dustin K
Test Fit:
Randy B
Video Edited:
Chris R
Written by:
Shelly K
Updated by:
Sarah W
Video Edited:
Zach D
Test Fit:
Brent H
Photos by:
Jeffrey L
Test Fit:
Shane H
Video by:
Jonathan Y
Test Fit:
Robert C
Test Fit:
David F
Updated by:
Isabelle B

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.