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How To Charge the Battery On a Honda CR-V While In Tow  

Updated 05/29/2025 | Published 06/21/2019

Question:

I am preparing to set up my 2011 Honda CR-V to tow behind my 2011 Winnebago. In addition to the signal/brake/running lights I need to charge the battery as I plan to use my Patriot brake system plugged into factory cigarette/power outlet in the Honda cabin. I have attached a pic of the cover to the 7 way connector on the motorhome and it looks like there is a power line. I called both Winnebago and Freightliner and they both told me there is NO charging line on my RV which I identified to them with the VIN. Winnebago said they didnt start putting in charging lines until late 2011-2012. Freightliner said if there is no circuit breaker labelled TOWinch then I do not have a charging line. There is no circuit breaker labelled TOW. Is there a way to check the plug at the RV end to see if there is power to run a charging line? If they are right then how can I keep the Honda battery charged while towing. In another vehicle Saturn Vue which I tow on occasion if have a battery blade disconnect switch on the Saturn Vue battery and ran a fused line directly from the battery to a 12-v power outlet I added to the dash to power my Patriot brake system. I disconnect the Saturn battery while towing and it hasnt gone dead in the the 5 years I have towed it. Should I do the same thing with the Honda? Sorry this question is so long........Thanks.

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Expert Reply:

Yes, in order to check to see if you have a trailer battery charge line ran on your 2011 Winnebago Motorhome all you will need to do is test the pin on the 7-way in the 1 o'clock position with a circuit tester while the vehicle is running. If you have power here then you know you have a trailer battery charge line ran. If not, you can do this pretty easily yourself with the Roadmaster Battery Charge Line Kit for Motorhomes part # RM-156-75. For your 2011 Honda CR-V, you will also need the Roadmaster Battery Charge Line Kit for Towed Vehicles part # RM-156-25.

The battery does not need to be disconnected on your CR-V but you will need disconnect a fuse which can be found in your owner's manual. I recommend using the Roadmaster FuseMaster Fuse Bypass part # RM76511. The 12 Volt Outlet Kit part # RM-9332 is also needed to provide constant 12 volt power to the Blue Ox Portable Patriot Braking System part # BLU37TR.

expert reply by:
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Conner L
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Reid profile picture

Reid

5/27/2025

Hi Conner, I am getting ready to tow my 2009 Honda CRV and purchased the HM56300 taillight wiring kit which only has a 4 pin connector (installed this past weekend). I also purchased the RM-156-25 battery charge line kit which will not work with the wiring kit, unfortunately I did not know this before install. What parts do I need to make this happen? I have a 2013 Thor Four Winds 26A in does have what looks like a 7 pin connector. Thanks, Reid

Jerred H. profile picture
Etrailer Expert

Jerred H.

5/28/2025

@Reid Hey Reid. You will need the Roadmaster 7-Wire to 6-Wire Flexo-Coil Kit item # RM-146-7 to get your 4-way connector modified into a 6-pin to work with a charge line and then connect to your RV's 7-Way.
Reid profile picture

Reid

5/29/2025

@JerredH Thank you!
Jerred H. profile picture
Etrailer Expert

Jerred H.

5/29/2025

@Reid You're welcome!

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