Trailer Winch wiring. Do I need to ground the battery?

[The Butcher]

I just ran a quick connect to the back of my dad's new Super Duty (I know it's a bad word on this site, but I have to admit it is a nice truck). I grounded the quick connect on the back to the hitch frame, and then I ran the hot lead all the way up front to the battery. The kit came with an 18" wire that says to ground the battery to the frame, or the engine to the frame (in case the engine is isolated from the frame by rubber mounts). Since it is a diesel, it has dual batteries. I wired the circuit breaker for the winch to the passenger side battery. From what I could see, the driver's side battery was grounded directly to the frame. The two batteries are run in a series (I didn't see an isolator between the two of them). Do I need to ground the passenger's side battery? (I forgot to look to see if it was directly grounded to the frame). If it is grounded to the frame am I fine without running the extra ground wire the kit came with?

BTW, this is a superwinch S4000 utility winch. It is going in the front of my dad's 14' covered car trailer.

 

[AZ79K5Project]

If these batteries are in series, then you are running a 24 volt system.

The the driver's side positive goes to the passenger side gound? If this is truly the case DON'T hook the positive of the winch to the second battery. More than likely the batteries are parallel, which gives you high power for a 12 volt system.

The ground from the battery is established and you grounded the quick connect to th frame. The problem comes into play with the ground from the battery to the frame. Depending on the overall draw of the system when you run the winch, you could over heat the ground at the battery if it is not large enough to handle the overall circuit (winch and accessories).

I would expect it to be OK if it is dual battery system.

 

[73k5blazer]

The bigger winches just have a cable of the same size as the feed, for the ground, run right to the battery.
This winch is a bit smaller,less amp draw, but you need to ensure that the frame to battery ground, if any, is big enough. Most vehicles have a ground from battery to engine (since the largest amp draw is the starter so they run the shortest big wire they can from bat to engine) and engine to body/frame via a ground strap.
If your unsure, I would just hook up the wire in the kit from battery ground to frame. I'm unfamilier with Fords, espcially dual bat setups, you should be able to visibly see the main grounding setup. Follow where the ground goes from battery to someplace.
But, like I said, if you unsure, just hook that wire up from battery to frame.

 

[The Butcher]

Yeah, I guess it is parallel. The positive on one is hooked to positive on the other. I did follow the ground from the driver's side battery, and from what I can tell it is directly to the frame. Those engine compartments are stuffed full, and following the wires is sometimes difficult b/c they snake behind stuff. I'm pretty sure the wire I found tied to the frame was indeed the connected to the negative terminal. I think it should be ok as I have wired it. I would think the Ford engineers would have run a suitable wire from the negative to the frame.

 

[73k5blazer]

Carful, suitable for a factory electrical engineer beat up by bean counters constantly, is the smallest size possible that will carry the load at a certain duty cycle. On a truck, that will include a reasonable amp draw from a large trailer, but a winch may not have been in that plan. But it's probably ok, as the winch isn't really big, and it's only on for a short time.
If you had to guess, what size is that wire you found. 12ga? 10ga? 8ga?
What size is the wire they included in the kit?

 

[The Butcher]

The kit came with 6 gauge. The battery ground looks to be 4 or bigger. I'm guessing it will be ok. If it starts to smoke the wire, we'll know it wasn't big enough, huh?