Cut-Out relay for winch power

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FT_Guest3342

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I have heard horror stories about vandals doing bad things with winches on parked vehicles. So whenever I install a winch the first thing in the power circuit is a 500 amp continuous duty relay. One side of the relay is hooked to the battery and the other is hooked to the winch controller. On the Tremor I used an up-fitter switch as a winch enable to activate the relay sending power to the winch controller. Also, although the installation instructions that come with the winch say connect it to the passenger (main) battery, I connected to the auxiliary battery instead.

To activate the winch requires that you have the key on so no vandal can hook your winch line over the top to your rear bumper and use their controller to reel it in.

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Dealer installed mine and I was surprised I could operate it without turning anything else on. Just walk up, plug in hand control and push the button. I may have to make this mod on mine. Thanks for posting! ?
 
Hi there. I have a question. Am I not able to just hook mine into the Upfitter switch and achieve the same safety result. What does the 500 amp relay do? Is it just to protect the switch? Thanks for the info!
 
Hi there. I have a question. Am I not able to just hook mine into the Upfitter switch and achieve the same safety result. What does the 500 amp relay do? Is it just to protect the switch? Thanks for the info!
Your switch is rated at 20-40A depending on which one. The wiring to the factory upfitter relays can’t handle the full power of the winch in both wire size and relay size. So the upfitter relay trigger this relay as it can handle the load.
with your upfitter the wiring size and relay size are predetermined if you tried to run the winch power off of it directly it would pop the relay/fuse and pull a lot of amps through the tiny wire risking fire.
(Tried to make that as simple as I could.)
 
Your switch is rated at 20-40A depending on which one. The wiring to the factory upfitter relays can’t handle the full power of the winch in both wire size and relay size. So the upfitter relay trigger this relay as it can handle the load.
with your upfitter the wiring size and relay size are predetermined if you tried to run the winch power off of it directly it would pop the relay/fuse and pull a lot of amps through the tiny wire risking fire.
(Tried to make that as simple as I could.)
Said perfectly. Thanks.
 
Your switch is rated at 20-40A depending on which one. The wiring to the factory upfitter relays can’t handle the full power of the winch in both wire size and relay size. So the upfitter relay trigger this relay as it can handle the load.
with your upfitter the wiring size and relay size are predetermined if you tried to run the winch power off of it directly it would pop the relay/fuse and pull a lot of amps through the tiny wire risking fire.
(Tried to make that as simple as I could.)
Thanks for the good info!
 
I am adding to this thread because several people sent me questions. So I will provide my info here.

General description:
The relay has 2 large connections and 2 small connections. The relay acts just like a switch except instead of activating it manually it is activated by a voltage. 1st the 2 small screw posts are how the relay is activated. If you connect a 12 volt signal across these terminals it will activate. One of the small screw posts is connected to ground and the other is connected to a +12 volt signal (connect to any of the upfitter outputs, preferably #1-4). This will let you turn on the relay from inside the truck. The 2 large connections on the relay are for the thing being switched. Connect one of the large screw terminals to the battery (+ terminal), the other connects to the +12 volts (red cable) from the winch controller. Now when you flip the upfitter switch the winch controller will get power.

Some specifics:
1. The winch power cables size are #2 AWG (American Wire Gauge). The cables from ford are way longer than needed if you are connecting to the driver side battery. If you want to shorten them you will need some way to obtain and connect new cable ends. Amazon can help with both.


2. Connecting to the battery. You will need to make a short red cable to connect from the battery + terminal to the relay. The battery terminal on the driver side does not have an extra post to connect to so you will have to modify it. I used a 1/4" drill and a stainless steel bolt to connect the cable. See the photo. I have more than one cable connected, you will probably only have one.
2021-06-01 13.17.32.jpg


3. The connection from the upfitter to the relay does not require a large wire. I used a 16 AWG wire. I put the wire in a red/black wire loom and dressed it along the rear of the engine bay. Drill 1/8" holes in the plastic to use wire ties to hold the loom in place. Any wires that I have going from the upfitter into the cab or under the truck follow the same path in the loom. It is easier to get into the cab on the drivers side and easier to run cables under the truck on the drivers side.

2021-06-01 13.55.25.jpg


4. The black cable (negative) from the winch should connect to ground (the negative battery terminal). On the driver side battery the negative terminal already has an extra cable connection stud. Mine did not have a nut on it and nothing connected to it. The stud requires an M6 nut.
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Last edited by a moderator:
I am adding to this thread because several people sent me questions. So I will provide my info here.

General description:
The relay has 2 large connections and 2 small connections. The relay acts just like a switch except instead of activating it manually it is activated by a voltage. 1st the 2 small screw posts are how the relay is activated. If you connect a 12 volt signal across these terminals it will activate. One of the small screw posts is connected to ground and the other is connected to a +12 volt signal (connect to any of the upfitter outputs, preferably #1-4). This will let you turn on the relay from inside the truck. The 2 large connections on the relay are for the thing being switched. Connect one of the large screw terminals to the battery (+ terminal), the other connects to the +12 volts (red cable) from the winch controller. Now when you flip the upfitter switch the winch controller will get power.

Some specifics:
1. The winch power cables size are #2 AWG (American Wire Gauge). The cables from ford are way longer than needed if you are connecting to the driver side battery. If you want to shorten them you will need some way to obtain and connect new cable ends. Amazon can help with both.


2. Connecting to the battery. You will need to make a short red cable to connect from the battery + terminal to the relay. The battery terminal on the driver side does not have an extra post to connect to so you will have to modify it. I used a 1/4" drill and a stainless steel bolt to connect the cable. See the photo. I have more than one cable connected, you will probably only have one.
View attachment 25051

3. The connection from the upfitter to the relay does not require a large wire. I used a 16 AWG wire. I put the wire in a red/black wire loom and dressed it along the rear of the engine bay. Drill 1/8" holes in the plastic to use wire ties to hold the loom in place. Any wires that I have going from the upfitter into the cab or under the truck follow the same path in the loom. It is easier to get into the cab on the drivers side and easier to run cables under the truck on the drivers side.

View attachment 25050

4. The black cable (negative) from the winch should connect to ground (the negative battery terminal). On the driver side battery the negative terminal already has an extra cable connection stud. Mine did not have a nut on it and nothing connected to it. The stud requires an M6 nut.
View attachment 25055
Thanks for the detailed explanation and write up on how the relay works. I get it now! (y)
 
I am adding to this thread because several people sent me questions. So I will provide my info here.
Awesome write up...very helpful!

One question, sorry if I missed it. Is there any reason to choose one battery over the other? i.e., if cable run to passenger side is easier, can we go that route instead? Or is driver side battery isolated so a power drain from one still leaves a charged battery to start the truck?

Thanks!
 
Awesome write up...very helpful!

One question, sorry if I missed it. Is there any reason to choose one battery over the other? i.e., if cable run to passenger side is easier, can we go that route instead? Or is driver side battery isolated so a power drain from one still leaves a charged battery to start the truck?

Thanks!
From what I can tell the batteries are connected in parallel. My reasoning on connecting to the driver side battery is that the cables are shorter. Shorter cables can carry more peak power.

Normally when 2 batteries are installed there is an isolator between them so you can select when they are connected and so both don't drain down at the same time. Also with an isolator if one battery goes bad it doesn't kill the other.

In this case there is no isolator so it doesn't matter which one you connect to. I did notice that the cables that connect the batteries together are a much smaller gauge, maybe 4 AWG. So that may limit the amount of power you can pull from the main (passenger side) battery and alternators.
 
Planning on adding this relay when I get my truck, and something I've been thinking of: any reason not to hard-wire the relay to ignition power? Just tapping into an existing circuit somewhere?

That would save an up-fitter switch, but I believe give exactly the same benefits otherwise. Only downside I can see is it would activate the relay many more times (every time the ignition turns on/off as opposed to only when the winch is used), but presumably these relays are built to be used.

Edit: to clarify, I'm referring to where the signal side of the relay connects - upfitter switch vs direct ignition power. The main power side will still be connected to the battery and the output side will connect to the winch.
 
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Planning on adding this relay when I get my truck, and something I've been thinking of: any reason not to hard-wire the relay to ignition power? Just tapping into an existing circuit somewhere?

That would save an up-fitter switch, but I believe give exactly the same benefits otherwise. Only downside I can see is it would activate the relay many more times (every time the ignition turns on/off as opposed to only when the winch is used), but presumably these relays are built to be used.

Edit: to clarify, I'm referring to where the signal side of the relay connects - upfitter switch vs direct ignition power. The main power side will still be connected to the battery and the output side will connect to the winch.
You could tap into an existing circuit, however you want to make sure that you don't overload the circuit to turn on the relay. If you have an upfitter it has an ACC wire that you can use for that purpose.

I used an upfitter switch because I wanted to be able to select when the power relay was on. There are several things in my truck that I don't want to be powered all the time. My CB, Ham radio and my Wifi camera all are connected to the output of this relay. The radios really want to be connected directly to the battery to minimize any wiring noise. However If you do that and accidentally leave the radio on you risk running the battery down. So one of the wires from this relay is a 8 AWG hot wire that goes to the inside of the cab. It powers a 6 position fuse panel where all the in cab accessories connect.

30 Amps for Ham radio, 10 Amps for CB, 2 Amps for Wifi camera, ....

Screenshot from 2021-07-06 00-10-24.png
 
Last edited by a moderator:
Planning on adding this relay when I get my truck, and something I've been thinking of: any reason not to hard-wire the relay to ignition power? Just tapping into an existing circuit somewhere?

That would save an up-fitter switch, but I believe give exactly the same benefits otherwise. Only downside I can see is it would activate the relay many more times (every time the ignition turns on/off as opposed to only when the winch is used), but presumably these relays are built to be used.

Edit: to clarify, I'm referring to where the signal side of the relay connects - upfitter switch vs direct ignition power. The main power side will still be connected to the battery and the output side will connect to the winch.
If not for things like winches, what do you propose to wire to the upfitters…what are you saving them for? Just curious what other cool toys you’re thinking of.

I personally don’t like the idea of energizing the winch unless I specifically want it turned on. And I definitely don’t need to use it every time I drive the truck.

My winch came with a manual switch that I put under the hood and I use that for now. I’ve been looking at relays and found a 500 amp on Amazon for $60 with good reviews but haven’t bought yet. Which specific relay are you looking to install?
 
If not for things like winches, what do you propose to wire to the upfitters…what are you saving them for? Just curious what other cool toys you’re thinking of.

I personally don’t like the idea of energizing the winch unless I specifically want it turned on. And I definitely don’t need to use it every time I drive the truck.

My winch came with a manual switch that I put under the hood and I use that for now. I’ve been looking at relays and found a 500 amp on Amazon for $60 with good reviews but haven’t bought yet. Which specific relay are you looking to install?
If you are adding one of these relays, just make sure that it is rated for continuous duty.

As for my upfitter, it is used as follows:
1. Winch/Accessory power
2. Front Light bar
3. (future) Power for Travel Trailer. (connects TT batteries to truck batteries, for solar charging truck, and for powering TT appliances, not fully designed yet)
4. Flux Capacitor
5. Transfer tank pump
6. Air Compressor
 
You could tap into an existing circuit, however you want to make sure that you don't overload the circuit to turn on the relay. If you have an upfitter it has an ACC wire that you can use for that purpose.

I used an upfitter switch because I wanted to be able to select when the power relay was on. There are several things in my truck that I don't want to be powered all the time. My CB, Ham radio and my Wifi camera all are connected to the output of this relay. The radios really want to be connected directly to the battery to minimize any wiring noise. However If you do that and accidentally leave the radio on you risk running the battery down. So one of the wires from this relay is a 8 AWG hot wire that goes to the inside of the cab. It powers a 6 position fuse panel where all the in cab accessories connect.

30 Amps for Ham radio, 10 Amps for CB, 2 Amps for Wifi camera, ....

View attachment 27409
Thanks for all the details! That’s great info, and love the idea of adding a fuse block for everything.
 
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