Charging while towing

[Miriam C.]

I am fixin to make a sticky for ways to charge the TD battery through the tow vehicle. Please feel free to post your way and please add pictures of the steps.

This is a kit that Susann posted in the Ladies forum. It is probably expensive because of the 40' wiring harness.
http://www.lslproducts.com/TC_Broch.pdf

[len19070]

You can do this several ways, But I use a simple method that has been used on towing rigs for decades with no problems. This is the way an RV dealer will do it

A wire (#10) off of the hot terminal of the battery, to a 30amp fuse/breaker then back to the trailer.

On the tow vehicle side Beef up the ground on the plug to a #10 wire, and on the trailer side extend those hot & ground wires to the trailer battery.

Unplug it when your not towing.

I generally use a Bargman 7 prong plug (for tow vehicle and trailer), but any plug with more than 4 prongs will work.



Happy Trails

Len

[lisasweetie]

Thanks Auntie M, you are the best.

[iplay10us2]

Len:

I have the 7 round on my trailer already and an adapter on my car to convert my 4-way flat to a 7 round so I can make the turn signals, etc work. Would I just run a wire from the battery to the unused battery lead on the 7 round on my car and upgrade the ground wire (if needed) and just plug them together to charge?

Oh, and I would wire in the 30amp fuse, too.

Thanks.

[Nitetimes]

Gotta agree with Len here. This tends to get way over complicated around here. I don't believe it's all that difficult to disconnect your plug at night or when you stop for an extended period of time. Like he said, travel trailers have done it that way since....well pretty much since forever and it works!
If you like all the fancy dodads and can wire them in then go for it, if not just run a wire, stick in an inline circuit breaker at each end and just 'pull the plug'.

[madjack]

...there are lotssa ways to do this but unless you are into spending extra for stuff you just don't need, Len's way is an industry standard and is hard to beat...I would look in the fuse box and find an unused, switched circuit...most newer cars will have several......run a 10ga power lead from the fuse box (or the battery + terminal) to rear of vehicle...you will need a 10 ga ground wire as well...since I tow several different trailers, which all have 4-flat plugs, I like to take the charge and ground wire and run them to a 2-flat plug similar to to a trolling motor connection...this allows me to keep the standard 4-flat plug and not worry about 4to7 adapters. On the trailer, run your 2 10ga wires to the battery and put an additional inline fuse(on the + side) as close to the battery as you can...this setup will work quite well and keep ya protected as well......
madjack

[Nitetimes]

...there are lotssa ways to do this but unless you are into spending extra for stuff you just don't need, Len's way is an industry standard and is hard to beat...I would look in the fuse box and find an unused, switched circuit...most newer cars will have several......run a 10ga power lead from the fuse box (or the battery + terminal) to rear of vehicle...you will need a 10 ga ground wire as well...since I tow several different trailers, which all have 4-flat plugs, I like to take the charge and ground wire and run them to a 2-flat plug similar to to a trolling motor connection...this allows me to keep the standard 4-flat plug and not worry about 4to7 adapters. On the trailer, run your 2 10ga wires to the battery and put an additional inline fuse(on the + side) as close to the battery as you can...this setup will work quite well and keep ya protected as well......
madjack

Simple, ain't it??

On another note....most pickups and some SUV's already have a fused charging wire running to the back, it will most likely be orange and may not be connected up front or possibly just not have the fuse installed yet. They started doing this sometime in the 90's and it's now pretty much standard even if it doesn't have a tow package.

[madjack]

YEP, it ain't rocket science...just be sure the charge wire(+ side) is fused on both sides (at trailer battery and car/truck battery) for safety...don't want any smoke escaping...by the way, the orange wire on our Pontiac Aztek is designated for the brake controller and is not heavy enough to use for charging............
madjack

[Nitetimes]

YEP, it ain't rocket science...just be sure the charge wire(+ side) is fused on both sides (at trailer battery and car/truck battery) for safety...don't want any smoke escaping...by the way, the orange wire on our Pontiac Aztek is designated for the brake controller and is not heavy enough to use for charging............
madjack

You will consider that I did say 'most likely' and not beat me too bad right??

Most pickups have a blue wire for the brakes so it should be the other heavy wire in the harness (except white=ground). We didn't do a lot of lighter SUV's so I can't say for certain on them.
It would probably be helpful if anyone that's found an OEM charge wire in a particular vehicle would post the vehicle (and year), wire color and where found. Might save some folks a headache or two.
As always, when you are playing with your vehicle wires it's a good idea to have a 12v wire tester on hand, they don't need to be expensive and they can potentially save you a lot of fuses and $$$!

[madjack]

YEP, it ain't rocket science...just be sure the charge wire(+ side) is fused on both sides (at trailer battery and car/truck battery) for safety...don't want any smoke escaping...by the way, the orange wire on our Pontiac Aztek is designated for the brake controller and is not heavy enough to use for charging............
madjack

You will consider that I did say 'most likely' and not beat me too bad right??

Most pickups have a blue wire for the brakes so it should be the other heavy wire in the harness (except white=ground). We didn't do a lot of lighter SUV's so I can't say for certain on them.
It would probably be helpful if anyone that's found an OEM charge wire in a particular vehicle would post the vehicle (and year), wire color and where found. Might save some folks a headache or two.
As always, when you are playing with your vehicle wires it's a good idea to have a 12v wire tester on hand, they don't need to be expensive and they can potentially save you a lot of fuses and $$$!

...naw Rich, it would be way to much trouble and effort ...I'll have to check the schematic since I am going by an 8 yr old memory...and I am easily confused ...at present, i don't even remember a blue wire........
madjack

[wlooper89]

My arrangement is a 25A inline fuse at the tow vehicle battery positive terminal and #10 wire back to a 7-pin connector at the hitch. The wire is always hot as I did not want to make any other changes under the hood. There is also a fuse in the line from the trailer battery. In addition to this minimal setup I put in one bell & whistle, an automatic charging relay from Blue Sea Systems installed in the trailer electrical compartment. This permits leaving the trailer electric cable hooked up to the tow vehicle while camping as it will automatically disconnect the two batteries if there is no battery charging from either the tow vehicle or in the trailer. It is totally unnecessary. I added it just for fun.

Bill

[Senior Ninja]

Madjack,

I'm planning to add another deepcycle battery to the one I already have to provide power for Field Day in June where I will be using the batteries to power my Ham radios. Can I still charge them from the battery terminals in the car.
Thanks,
Steve

[madjack]

Madjack,

I'm planning to add another deepcycle battery to the one I already have to provide power for Field Day in June where I will be using the batteries to power my Ham radios. Can I still charge them from the battery terminals in the car.
Thanks,
Steve

I will say PROBABLY...you might wanna charge only one at a time if they are severely depleted to avoid over-stressing the alternator...part of that would depend on the size of the ALT...if it's oversized, it would probably be OK...if not, one extra at a time would be the way to go....
madjack

[Senior Ninja]

Great Idea Sir. I'll try it.
Thanks,
Steve

[madjack]

Steve, just make sure you are running at least a 10ga wire with a 30A fuse as close to the battery as possible...BOTH the tow vehicle battery and the 2nd battery.............
madjack