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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.
Hi, I am Daniel with etrailer and today we're gonna take a look at, I'm gonna show you to install the Roadmaster Battery Charge Line Kit for towed vehicles on our 2020 Ford F-150. This charge line kit is gonna be for flat towed vehicles and this is just gonna provide a trickle charge to your battery from your motor home so this stays nice and full so you don't arrive to the campsite with it dead. And a lot of these newer vehicles, it's a requirement to get one of these because your braking system is reliant on your battery. So you need this nice and charged, like for our Ford here today, it is required so you need to pick this one up when setting up your flat tow system. This kit is gonna come with all the wire you're gonna need and your circuit breaker. What's nice about this is it's gonna trip automatically, so if it's getting too much of a current, it'll trip and then it'll cool down and reset itself.
Now something to keep in mind is you will need a charge line kit for your motor home side. Most of the time, you will have that already installed, but definitely check that and get one if necessary. When setting up your flat tow setup, there are gonna be five main components and starting here at your vehicle side, you're gonna have your base plate and that's just gonna be the device that attaches to your vehicle's frame and it gives you anchor points for your tow bar. and your tow bar is this in the middle. It's just gonna be the in between, between that base plate and the hitch on your motor home.
Then you're gonna need some safety cables as an extra measure of safety. Then you're gonna need your braking system and that's gonna be inside giving you proportional braking when you're going down the road. And then you'll need your wiring. So this will transfer your brake lights and turn signals to your towed vehicle. There are a couple other things you will need specifically for your F-150 and that is gonna be a brake light relay.
Now if you have any further questions about this piece of kit for your flat tow system or any other components, 'cause I know it is a lot, feel free to reach out to us, here at etrailer and we'd be happy to help you out. As far as getting this installed, it is really straightforward. You're just running some lines to your seven pole plug on the front and then connecting to your battery so it's not too bad. But if you don't have the timer tools to do this yourself or you wanna get your whole set up done in one go, you can check out our Dealer Locator. We can find a professional in your area to get this installed for you.
But if you wanna do it yourself, follow along and in this video, we'll show you how to do it. First off, I have our red wire that comes in the kit. I'm gonna connect this to our plug and that's gonna be the center post on the plug. So I've already spliced this, I'm just gonna put that in there. Use a small Phillips head and tighten the set screw down. I got our plug mounted and our bracket and I've already routed that wire, but that red wire like we connected to our plug that is routed over to our passenger side and I went down and around our frame and there's a big pocket that I just ran it all the way up and just zip tied it to an existing wire harness to keep it up here into the engine bay. Now we need to find a spot for our circuit breaker. So there's actually a piece of really hard plastic right by our battery, so I'm just gonna self tap it to this. So your kit comes with some self tappers. I'm gonna use a 5/16th drill bit and get this secured. (drill whirring) I will splice our red wire and crimp on an eyelet and this is gonna go on our copper post. It's labeled Battery, so this will just get put on there and I will tighten the nut back on. And then your remaining wire in your kit, I'm gonna do the same thing. I'm going to splice this, get a eyelet crimped on and then this is gonna go on our silver post and this will go to our battery. I'll use a 10 millimeter socket and I'll just get these tightened down. (tool clicking) I'll use a 11 millimeter socket to take off the nut on our positive post. And on the other side of our wire, we'll get the larger ring terminal and crimp this on. And I'll put this on our post and get this tightened back down. (distant drill whirring) Once you have everything connected, you can go back through and zip tie all your wires back and make everything look nice. I have some other wires to connect here to finish up this flat two setup, but for this component, it's good to go. The charge line is set up on our 2020 Ford F-150. Thanks for watching.
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.
Info for this part was:
At etrailer 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.
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,