Charging a trailer battery without a geni

[Gold5th]

Sooo I'm not towing an enclosed or anything, or a proper "sled" trailer.. but I figure some of you may know.

On the front of my trailer I have a "tool box" where I store my tie downs and winch and and and... and well a battery for my winch.

My winch connects to the trailer deck to pull whatever I need up. Currently I take the battery out bring inside and charge it. So without completely re-wiring my truck and trailer is there an easy way to charge it? I only winch sometimes so a slow charge is fine, and the winch only needs juice from the battery.. it's a small winch.

I'm wondering maybe if I can some how limit the current like the 5A, maybe 10A, I could piggy back how ever the trailer brake disconnect backup battery charges..

Any ideas would be great.. thanks

 

[fastlane]

Depending on what model truck you have, it should have a 12v power supply back to the trailer plug, you can run that to your battery and it will charge it as you drive, with the breakaway battery, also you can buy 12v trickle chargers/batt minder which would do the same thing, if it is factory wired the truck 12v supply should be fused already. I charge my winch battery this way and have not had to change it out yet, 4yrs old. hope that helps.

 

[Smoothlander]

Make sure you add a battery isolator if you charge using your truck battery as described by fastlane.

 

[Highmarker]

What is the point of a battery isolator? Isn't the 12v supply switched with the key so it wont drain the truck battery while parked?

 

[Gold5th]

My concern is that the trailer wiring harness isn't "beefy" enough to handle the load of a winch, so I would need a limiter. I'm pretty sure my truck does have the 12V on my 7 pin, but the trailer wiring harness is a "1 piece" so I'd hate to splice in/re-do it as the trailer is only 1 year old. The Breakaway box is right next to the the tool box, which is why I was hoping to piggy back it.

My Brother-in-Law's idea was I should run a second cable a 4ga wire or something to the back and have a second "trailer plug" to charge the battery, but that could get annoying, but if I needed the extra "juice" it would be nice.

I guess I'll have to take off the tool box, open up the breakaway box and see what wires are in there for me to use.

Does anybody know a way to "limit" current flow by a means other than a fuse.. like something that; no matter the draw demand will only let through X amount of Amps. Where as a fuse just pops...

Thanks again

 

[Gold5th]

Erm heh... well I posted a big long blurb about I want to do on an Electrical Engineering forum, and just as I clicked "post" I realised there's asuper simple way to do this. It's not automatic like was hoping... but worst case, I see what wires feed the breakaway battery charging circut.. or if it even has a "real" circut to it, splice off from there, and just before I get to the POS terminal on the winch battery put a simple switch.

Not winching: have switch on
Winching: turn switch off..

Heh well if the other forum has a funky answer I'll post it here.. just incase other people have similar needs.

I'd have to find a good spot to put an isolator to prevent trying to crank off the winch battery though..

 

[Gold5th]

Soo I thought about it more.. and a simple switch method won't work, not even with an isolator.. the potential for a huge surge is to high. Either via cranking(isolator fixes this), or reverse if I drain the trailer batt to low the alt may try to sove 100A+ down the 16a wire to charge it quick like.

Grr

 

[I'LL WIN]

Your truck's stock harness should be fine for this. It will only let so much power go through it before tripping the fuse which should be an automatic resetting type. An easy solution would be to simply unplug the trailer when winching if you are concerned the winch will cause a problem. Even if you run the trailer battery dead your truck's harness is designed to charge an RV battery even if the RV battery is totally dead. Just add the wire from your trailers plug to your trailer battery and you are done. If that battery is too small put a bigger battery on the trailer.

 

[Gold5th]

That's where I could run the switch rather than unplug the trailer... most time's it's dark when I'm loading stuff, so I want the lights on the trailer on so I don't get hit type thing..

Hopefully tomorrow I'll get a chance to look and see just what all is run to the breakaway battery box. It would be nicer to do that rather than have to mess with sockets and what not as like i said the trailer is new.

I have a '04 Dodge Durango if that makes a difference, with the factory tow kit/harness and a Prodigy brake controller.

Thanks again