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Kit allows up to 15 amps from your RV's battery to be used to maintain the charge of your towed car's battery while the car is being towed. Charge line connects to the 6-way or 7-way plug on your vehicle. Requires separate charge line in RV.
Features:
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Today on our 2017 GMC Acadia we're gonna take a look at and show you how install the Roadmaster Battery Charge Line Kit for Towed Vehicles. Part number is RM-156-25.Now, our charge line kit takes care of the problem where when we tow our vehicle the battery drains down. Typically you'll have to leave the key on in a vehicle requiring a charge line kit, so some of the functions stay running. What this provides us is a 15 Amp charge going to our battery; it's gonna get it from the connector plug on the front of our vehicle hear, just run the provided wire up to our breaker, and then once it goes through our breaker we'll just run that onto the battery post. It's gonna give us a constant charge.The breaker is designed to prevent this from overloading, so if we're working this too much, or if we've got some kind of a major draw going on, at a point the filament inside's gonna come up to where it's not making contact. So that allows everything to cool off a little bit, and as it cools it's gonna come back down, make contact, and again continue charging the battery for us.
Now this is gonna work any time that we have our vehicle plugged into our RV, when the 12 Volt signal's live. Now, some RVs have a constant 12 Volt signals, some RVs will have a 12 Volt signal back only when you've got the ignition on, so be sure to test that out. And if you don't have 12 Volts at the back of your vehicle, you can use the RV Charge Line Kit, which is part number RM-156-75, to give you a connection from your RV's battery to the back of your RV.Now for the installation of the charge line kit, we'll take the length of wire, and we're gonna be running this from the plug on the front of our towed vehicle, up to the battery. As you can see we still have the fascia off, this is the opportune time to do this, that way you're not gonna be fighting with trying to get your arms in behind there or something like that. Now, we'll just start our wire here at the front of the vehicle, so we can attach that to the plug.
The other end of our wire, we need to run this up to our battery. There's a little gap right here, it's pretty easy to go right through there, and it gets you back in here, behind the panel. We'll just want to bring that excess up, and the of course zip tie off right here to keep our length.All right, now you can see our charge line wire, we've brought it up here. This, depending on your coach, the best way to do it would be to plug in your pig tail and test and see which pin that you have your 12 Volt signals, well that's the one we wanna connect to. And in our case, from our RV, that's gonna be the center.
So as we put our plug in place we'll be using that center wire. We'll just strip back that wire, we're gonna give that a good twist, and like we said, since the center point's our 12 Volt power, that's where we'll need to connect it.Now we'll finish running our wire back here, this is the positive post on the battery. I think we're gonna be putting our breaker right in this area, so it should work out pretty well, we should have close to the right amount of wire. Just kinda keeping it tucked down, down and under, kinda keep it hidden. And we're gonna leave just a little bit of extra there, trim it off, then we'll strip both ends back.
Now, in our kit we have three ring terminals, we wanna use the two smaller ones on those ends. All right, set those aside for now and get our breaker in place.You see the two tabs on the breaker are gonna stick out, and we've got the self tapping screws provided to get it secured. I'm gonna tack it right underneath this plate here, keep it protected, kinda down and out of the way. With that mounted in place let's pull the nuts off of each side. Now the wire we brought up from the plug on the front is gonna go to the silver stud. Now, to tighten that up you're gonna use a 3/8" wrench or socket, whatever you need. Now to the copper side, we'll attach our jumper there.Now, if we press in on these two tabs, here and here, we're gonna open our cover up. Then we'll bring our jumper wire, we're gonna go right to this stud, that's gonna be in a direct link through the fuse to the positive post. Trim that off, strip it back, and add the larger ring terminal. Now we're gonna connect this right to the stud here. To remove that nut you'll want a 13 mm socket. Place our ring terminal over and then replace our nut. Then we'll use a couple zip ties and just zip tie that off to that cable.Now with everything secured, that's gonna complete our installation of the Roadmaster Battery Charge Line Kit for Towed Vehicles, part number RM-156-25, on our 2017 GMC Acadia.
Customer Satisfaction Score:
96% were satisfied with this product
4% of customers were not satisfied
Ratings & Reviews
Jeffrey
11/19/2022
I have no regrets with this purchase. Items preform as advertised with no issues. I am very satisfied with Roadmaster and Demco products.
Ken
2/27/2026
Great little product. Worked great while we needed it flat towing and the brake controller and lights were being activated. Now the Jeep is babied , trailered and enclosed.
Gwendolyn Y.
2/27/2026
Victoria H.
1/9/2025
That's awesome Ron! I will let them know you reached out.
Ron
12/20/2025
The Roadmaster accessories work great - the brake switch in the car is ideal for turning it on and off as required.
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Condition: Like New
Notes: May have damaged packaging or minor cosmetic blemishes.
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Roy
7/30/2018
Still very happy with our purchase. We’ve towed over 10k miles and have had zero issues with our tow setup. I’ve shared my experience with several other RVrs and recommended your company for their needs. Thank you,