Wiring a trailer to charge off the tow vehicle

[@user-sp5bn6ye8y]

The circuit breaker, or fuse, is wired in-line (wired in "series") to protect the WIRE. Not what its supplying power to. Always rate the wiring size to the electrical load requirement, and then install a circuit breaker/fuse to protect that sized wire. -I'm an electrician

[@jhendren0001]

And I was wondering about how to keep my battery for the winch charged thank you sir 🙏

[@JasonTheMunicipalMechanic]

No problem.

[@appliancerepairshorts]

You might want to add a solar charger to charge it when not being used

[@Laura-lr3sz]

@@appliancerepairshorts How would one do this?

[@davidbradford9690]

So basically. Open the box the 7pin wire goes to. Add wire from the black wire/12v supply to your trailer battery. This should keep your battery charged and even voltage with tow vehicles battery. Just dont put a huge strain on trailer battery.

[@angeloiezzi7054]

lol, exactly, this was a long way to say that, but yes. That is what I got out of this too.

[@kennyhall7711]

You can also install a diode so power can't flow backwards

[@rafaelordonezjr6149]

Thanks for taking the time to Make this video!

[@gregoryford4705]

Thank you very much again I tried to get a picture of what I did by following your video.

[@JasonTheMunicipalMechanic]

No problem. Glad I could help.

[@kennyhall7711]

I've found it alot easier to just wire a 12v outlet into the trailer box and get a 150watt power inverter and hookup a small 2-3amp trickle charger/maintainer. Easy to do and shouldn't overload the curcuit.

[@ChickenWhisperer1000]

Great video. Exactly what I needed

[@waznme3920]

Did you hook up ground to white wire?

[@barntt]

First you said upper Right, then upper Left then at the vehicle you pointed to upper Right? I'm so confused! I GOT IT! LOL!

[@johnkemnitz7478]

If I am running a winch to load logs and my battery starts to get drained wouldn't it try to pull the amps from the little wire coming from the seven pins. The winch 2500 badlands on my crane draws up to 300 AMPS at full load and 55 at 1,000 lbs. So when a battery starts to lose power the voltage goes down and if the tow vehicle tries to keep it at 12 and higher wouldn't that course a large number of amps coming from the tow vehicle when coupled to the battery that has the draw?

[@JasonTheMunicipalMechanic]

It’s possible I would keep an eye on it if it gets hot. Your not really in a series configuration, its going to be in parallel so I think it would draw mostly from the battery, but you should have a fuse or breaker that would trip if it draws too many amps.

[@JasonTheMunicipalMechanic]

This method of charging is mostly for RV batteries and things of that nature. if your intention is to use it to keep a battery charged so you can run a winch continuously I don’t think that the small charging wire is going to suit your needs. You are probably going to have to put in heavier gauge wiring and probably a bigger alternator if you’re drawing 300 Amps continuously you might be better off just running a set of jumper cables from your main battery to your winch battery on whatever you’re loading with. I haven’t had any problems with my dump trailer for the years I’ve owned it but it doesn’t run continuously either it just dumps and then charges while I’m driving.

[@dalechalkey3729]

John, you are correct. When the battery starts dropping from 12 volts the current from the vehicle will increase to many amps and the inline fuse on the tiny wire will blow. The fuse might be rated at 15~30 amps so that is the limiting factor. Once the battery has a heavy load on it, it will only be a matter of time before this approach pops the fuse.

[@RALPHD099]

you can install a diode to make sure it only charges and doesn’t pull from the small wire…

[@waznme3920]

You could always try using a connection like battery powered forklifts. Hooking up to the alternator then you can leave the tow vehicle running to keep battery charged. I think his method is more for cargo trailers or fuses that are winching cars up on a trailer

[@josephlenzsch3628]

I just had a question I was going to set up everything the same way as you described but will the breaker from the charging wire prevent a heavy amp draw from a winch on a car trailer from drawing on the car battery or over heating the charging wire. Should I unplug the 7 way connector as a precaution? Thanks

[@JasonTheMunicipalMechanic]

I would unhook the trailer connector if your gonna put a large consists draw on it. I would imagine the breaker would trip but I don’t know how long it will take to disconnect. This set up is mainly for charging the battery’s not for supplying power to a load on the trailer. I will say I’ve never disconnected my trailer plug when running the hydraulic pump for the dump trailer and I have not had any issues but I cannot guarantee you will not encounter any problems.

[@josephlenzsch3628]

@@JasonTheMunicipalMechanic ok thanks for the quick reply I have a battery on the trailer I just wasn’t sure how the 8 or 10 gauge wire would react and didn’t want the winch to try and draw from the truck and the trailer battery. ultimately once I get the diesel running I plan to run a 4 gauge wire one way plug with 100 amp breaker.

[@Mj-CWO4]

So if I’m not mistaken you said hook the cable to the neg side of battery?

[@JasonTheMunicipalMechanic]

Your gonna hook the positive that comes through the trailer plug to positive with a breaker in line, and the negative that comes through the trailer plug to negative on the battery.

[@Mj-CWO4]

@@JasonTheMunicipalMechanic thanks that’s what I thought guess I misunderstood what you said

[@chrismiller7258]

So just off the black wire to positive on battery? You don't need a ground?

[@ohakuneyachtclub8753]

great video thank you. is there a risk that you could overcharge the trailer battery if you drove for say 4 hours a day

[@JasonTheMunicipalMechanic]

To be honest I’m not sure. It was only sending about 6-7 amps to the battery which isn’t much so I don’t believe it would be a problem. But honestly I don’t really know. I think the breakaway battery boxes are wired like this too so I’d imagine it would be ok.

[@mnotlyon]

No. It's using the power supply that the alternator creates. The alternator is designed to properly charge a lead acid battery.

[@23steph13]

Do you use a fuse or relay for the hydraulic pump?

[@JasonTheMunicipalMechanic]

The hydraulic pump is actuated by a relay, but I believe there is a circuit breaker that is inline in the control circuit of the controller.

[@23steph13]

@@JasonTheMunicipalMechanic ok thanks. Trying to hook mine up properly

[@JasonTheMunicipalMechanic]

I will look after work and see exactly how it is wired.

[@23steph13]

@@JasonTheMunicipalMechanic thanks

[@JasonTheMunicipalMechanic]

So I’m not suggesting this is the right way to wire the pump but it is the way brimar wired mine. There are no fuses on the pump wiring unless there is a fuse in the controller box I am unaware of. There is a large battery cable that delivers positive to a large relay that is mounted directly to the pump motor. A small wire is paired to the battery cable at the stud on the relay that feeds positive to the controller box. A wire comes out of the controller box and is attached to the energizing stud on the relay to engage the relay and run the pump. Another wire comes out of the controller box and goes to the valve that opens and lets the fluid back into the tank so the body can lower. There is a large power cable that goes from negative to the pump motor case to supply ground.

[@joshuacolgin1892]

I'm confused. So do you have a ground from the neutral terminal to the trailer or do you have a ground going to the 7 pin?

[@JasonTheMunicipalMechanic]

Both. They will be connected at the junction box. Ground comes in on the 7 pin and goes to the junction box where it then goes to the trailer to provide ground for the lights. It will also go to the battery to provide ground to charge it.

[@EfBEye888]

Why would you need to run the white wire to the negative side if the battery, it’s already grounded in the junction box

[@heribertoperezteran8316]

Can a trailer battery runs a death battery truck?

[@MiStoner710]

This saved me a few 100 dollars, was able to fix my wiring on the trailer and the hydraulic pum0

[@JasonTheMunicipalMechanic]

Glad to hear it helped. Thank you.

[@THEREALDJREDD]

Hi Jason do I need need to install a relay if I'm using small battery (ie lawnmower battery). I'm only using it for a LED strip

[@JasonTheMunicipalMechanic]

If your asking about using a relay to power the led strip I would probably say no. I would check the amperage draw of the light and the rated capacity of the switch your going to use. But I would imagine it would be fine. If you mean a breaker for the charging of the battery I would put one in to protect the circuit if the battery goes bad or shorts internally.

[@THEREALDJREDD]

@@JasonTheMunicipalMechanic The amperage draw is less than 5A. It's a small 12V battery so that I can have the LEDs on with out having to have the tow vehicle connected and or using the LEDs on the battery when loading equipment at night.

[@JasonTheMunicipalMechanic]

I think you would be fine without a relay.

[@artest7]

Myabe I’m missing something but, I have a Renogy dc-dc on-board charger w/MPPT(for solar) that can charge my batteries from either my tow vehicle’s battery, solar panels or both! Renogy told me I would need to use seperate 4 gauge battery (+/-) wire/cable from my tow vehicle’s battery to the charger and couldnt use the existing 7-pin connector. Just curious if that’s kinda what ur doing?? Thanks for the video either way!!

[@JasonTheMunicipalMechanic]

I’m using the 7 pin connector positive wire to charge the battery. The smaller factory wire might not carry enough amps to work with your setup but for my dump trailer it works fine. I’ve had it for around 3 years and I haven’t needed to charge it. I’m not familiar with your charger so I’m not sure why it would require that size wire, but it might burn up the factory wire if it requires a high amp load. I’ve installed a 7 pin connector with a charging wire that came from etrailer, and the instructions required a 10ga wire to the plug. A 10ga wire will carry 30 amps and a 4 ga wire will carry 70 amps. I guess if you had a really dead battery it might draw a lot of amps. If they told you to use a 4gauge wire then I would recommend you use what they told you to use. Something to take into account is the size of your alternator depending on what the vehicle draws to run it can only send what’s left to the trailer, but a bigger wire would be better.

[@appliancerepairshorts]

What wattage solar charger you have? Also your solar charger should come with the required wire for its intended application. I have 2 -a 35 watts and it charger for a battery and running a fan. The other is a 20 watts works a a battery maintenance charger on my flat bed trailer.

[@kw4jm699]

Hello Jason. I have a 14.4 a lithium battery in my camper, so I have been told that I should disconnect the alternator from the camper because it could overheat the alternator and burn it up. So.... how do I disconnect the alternator from the camper in a 7 pin arrangement? Thx! Good video. Scott

[@JasonTheMunicipalMechanic]

If you are looking at the terminals on the trailer connector from the front, the upper left wire is the 12volt power wire from the vehicle. That is the one you should disconnect if you mean you want to disconnect the charging from the vehicle. Depending on your vehicle there is probably a fuse for the charging wire on the vehicle. You can probably just pull the fuse in the fuse box too

[@kw4jm699]

Thx Jason. So it’s just a matter of disconnecting one wire. I think I can do that. Thx again. Scott

[@thisismyalt9010]

you need to use a dc to dc charger on the lithium battery. lithium batteries have lower internal resistance than lead acid. lower resistance pulls way more amps.

[@scotsmanofnewengland7713]

Why can’t someone sell the connectors with the pin locations color coded or at least numbered. Thanks for the video

[@hikerJohn]

Do you think the truck limits the amperage so you don't melt your wire? I see people say that a low trailer batter will draw too much but that wont happen if the alternator is limiting how much is going down that plug wire. Some people are saying we need to buy a $100.00 DC to DC charger. I did not have a DC to DC charger on my Airstream but now I'm trying to wire a cargo trailer that has a 100A Battery. I'm driving a 2010 F-250 Diesel with what I think has a 135amp alternator.

[@JasonTheMunicipalMechanic]

I don’t really think the vehicle will regulate the power to the trailer plug, but I guess it’s possible. The vehicle uses power to run everything on the vehicle and also put power back into the battery so you more than likely won’t be sending full power to the trailer battery anyway. I think if it was burning up wires and starting fires then they wouldn’t be wiring trailers like this from the factory. There is a 30-40 amp fuse on my trailer so I know it isn’t getting more than that, and if for some reason it was getting enough power to melt a wire (providing it is the correct size) then it would blow the fuse in the fuse box or trip the breaker on the trailer. I could be wrong so I would recommend not doing anything your not comfortable with. I’m not sure about any special type of battery though. I’m using regular lead acid battery’s so there may be differences there.

[@hikerJohn]

@@JasonTheMunicipalMechanic A read a few more posts in a Ford F-250 forum and they all were saying there's just enough current to barely charge a trailer battery so it's more a maintenance current so now I think the truck MUST be limiting it. I have full battery voltage at the trailer plug. The brake controller also uses that wire along with a blue break wire (in the 7 o'clock position in the plug on the truck) I already wired it into the trailer but I have not connected it to the battery so I will leave it disconnected until I think I need it (like if my generator wont start) or to do a test . . . Fun . . . LOL If only I had a proper truck wiring diagram.

[@JasonTheMunicipalMechanic]

I’ve gotten a few manuals from Emanuel.com and they were pretty good. Not very expensive either.

[@ceciliachan4361]

Can it over charge the trailer battery? Is there a way to discharge when it maxes out? Thanks! :)

[@JasonTheMunicipalMechanic]

I don’t believe it would over charge, but I’m not sure. I haven’t had any trouble with mine. It doesn’t send much power to the battery, it depends on the vehicle but my gmc basically just connects the battery to the electrical system by tying it to the main battery on the truck. With the vehicle the battery is used for storage to start the vehicle and for power with the engine off. The alternator actually runs all the electrical when the vehicle is running unless it can’t keep up with the load, but charging power is always supplied to the battery at least in older vehicles without smart charging systems. If it’s not over charging the truck battery why would it over charge the trailer battery. As for discharging the battery they don’t really get overfull like a pot of water. I guess it would depend on what your using the battery for on your trailer if this is a practical thing for you. My camper uses this method and my dump trailer does too and I haven’t had any problems with it. But like I said with my truck it just ties this battery in parallel to the electrical system on my truck through the fuse box

[@moctezumavelazquez1615]

What’s the blue cable

[@JasonTheMunicipalMechanic]

The break away switch for the brakes use this main battery instead of a small battery to activate the brakes if the trailer comes off the truck.

[@joshanderson8690]

huge help thank you

[@brandon-cz9tm]

now it all makes since 3:41

[@johnnynelson7853]

Jason, Excellent video Thank you! I am trying to duplicate the setup you show but I cannot find the small Vetomile unit you have mounted to your trailer. Could you tell me the model #, please? Thank you, again, John Nelson, Pasadena, TX.

[@JasonTheMunicipalMechanic]

Thank you. It’s just a trailer junction box. I think the vetomile is a brand or something. Here is one from amazon www.amazon.com/dp/B07PT5Y29V/ref=cm_sw_r_cp_awdb_imm_MZZBZK64D7SF3ZED3222 you can also search trailer plug junction box on eBay and will find some too. You can search around for some pricing. I seen them around 30 dollars and up to 60ish I would just make sure the brake wires are bigger like the 10ga in the one from the link.

[@mikeg3584]

How do I wire interior camper trailer to the battery on the tongue for power?

[@mikeg3584]

Helped so much thank you

[@JasonTheMunicipalMechanic]

No problem.

[@dustinrowley6739]

So all u need is a braker fuse and it work

[@JasonTheMunicipalMechanic]

On the trailer side that is how it’s wired from brimar and has worked since I owned it. Your tow vehicle needs to be set up to send power to the trailer plug though as well.

[@richardbaer711]

I mean my left. I mean your left. No way it's got to be your bowl okay if I want you.... Let's go to the vehicle your other.

[@gregoryford4705]

Thank you

[@JasonTheMunicipalMechanic]

No problem. Thank you for watching

[@johnnyluvsongwriter3260]

What if I have a four pin on the trailer?

[@JasonTheMunicipalMechanic]

You will have to add a 7 blade plug to it. You can remove the 4 pin plug and wire it into the 7 blade connector and add the wiring for the power and possibly a ground depending on how it’s wired.

[@dalechalkey3729]

The 4 pin connector doesn't offer a 12v feed like the 7 pin so you can't charge with the style.

[@jrcurtis12]

Very hard to understand and follow

[@BOONESVLOG]

🤦🏽‍♂️🤦🏽‍♂️🤦🏽‍♂️I thought it was just me would’ve gotten better instructions from a deaf person….my gooooddddd

[@jrcurtis12]

Watch the video u never did ever say how it worked or how it charged. To many hmmm and pauses . Alot better videos from a 1 yr old my goddddd

[@JasonTheMunicipalMechanic]

It works fine nothing to report. It’s the same method etrailer gives and it’s the same way brimar wires them. Pretty sad you keep coming back to give bad comments. Go figure it out for yourself somewhere else then. I don’t scrip my videos sorry it wasn’t to your liking. It was free and cost you nothing. Move on buddy.

[@interpinto]

You should take your confusion as a sign...Do not touch trailer wiring. Future mechanics will thank you later.

[@tomholskey992]

So take your ass to someone else's video and not have a clue what you are doing. Idiots like you are a dime a dozen online.

[@paulmartinez9409]

Thank you