I am putting a winch on my trailer and I got an optima marine battery to run the winch. I would like to wire it into my trailer wiring so that it will charge off the truck while its running, but so that it won't draw off the truck's wiring while I'm winching... I'm worried about the size of the wire and the fuse on the factory hitch wiring. I'm probably not going to be doing any extended winching, just pulling things up on the trailer. I may just unhook it from the wiring whenever I'm winching? What do you guys think?

 

btw the trailer already has a small battery to run my trailer breakaway system.

 

The wire between your truck and trailer only needs to be about 12 or 14 gauge since you only want it for charging.

The wire between your battery and your winch should be at least 8 gauge but your winch instructions should give you guidance on the wiring requirements under full load.

I STRONGLY recommend you get a solar powered battery charger as well. If that Optima goes flat for an extended period of time it'll kill it beyond resurrection and you'll be out of luck.

Here's a selection of cheap one's from HF:

Harbor Freight Solar Battery Chargers

I've got the 5watt model on my trailer w/Warn 3700DC connected to a BlueTop that matches the size I use in my race car and when the trailer is plugged-in to the truck and engine is off it charges three batteries. The one on the trailer and the two in the truck!

Here's some more styles from NorthernTool if you're in a NE state:

NorthernTool Solar Battery Chargers

 

The 7 pin on the truck has a switched 12V source. When the key is on and engine running the wire puts out 12v to the trailer plug which can charge batteries and whatnot. Turn the key off and the 12v is switched off I believe by relay. It is fused at 30amps so it won't allow a huge draw.

 

You're right, and that's a good point. I wasn't clear when I said "engine is off". I normally leave the key turned to the accessory position to charge radio's and keep the wireless access point running for timing/scoring access and data-logging while we're at the race track and why I went with the 5 watt charger otherwise I would have picked the 1.5 watt version just to keep the trailer battery topped off.

 

interested ! - can u 'splain your setup ? where mounted and how connected ?

appreciate it

 

So if I wire the 12 volt off the plug its not on when the key is off? thats good to know, that means I can wire that straight to the battery and just make sure I shut the truck off...

the solar charges are nice but not in the budget and there is no where for one on my trailer, but I will make sure the battery gets charged with my battery charger/maintainer after its used and topped off before use.

My winch is only a 3000 lb one so the current draw isn't huge, but it still will pull a good bit more than 90 amps. The wiring on the winch is like 10 gauge but based on my experience with a similar winch on my flatbed, I know I can get a bit more power out of it if I upgrade to some 6 gauge I have laying around. the good thing is that it will only be a run of maybe 18" to the battery.

when I have more cash I may wire the battery up with an isolator so I can use the winch without fear of it popping fuses regardless of key position.

 

Thats how my TT is wired up with its batteries. I have two deep cycle batteries on my TT to power pumps, lights, outlets, and whatnot. I have it wired to the plug to the truck so when I drive it charges the batteries and when I am at the campground and shut the truck off the trailer runs off the trailer batteries. Works like a charm!

I want to put a box with a battery and winch and whatnot on my car trailer some day and wire it the same way.