Wire a winch to truck system?

Hagar68 · February 9, 2023

2020 GMC Sierra 2500 gasser, base 170 amp alternator, 1 battery as built.

Want to install receiver winch but hesitant to wire it into all these computers. I know the truck measures total amp load thru a doughnut at the negative terminal, and that computer will actually increase idle rpms if alternator can't keep up.

Winch draws almost 400 amps full load, which would seem to look like a dead short to the computer.

How are folks powering these winches in these newer trucks without damage or setting a CEL?

asilverblazer · February 9, 2023

I ran a set of jumper cables, I cut the clamps off and added terminals so that I could connect it straight to the battery. I added Andersen connectors at the front and rear bumpers to plug the winch in to.

I also have a set of jumper cables with clamps on one end and an Andersen connector on the other - I can jumpstart other vehicles off those plugs at the front or rear.

Haven't had a problem with any of it yet.

Hagar68 · February 9, 2023

Thanks. The jumper cables are a good way to get the heavy wire. I did something similar with Andersen plugs as well.

Did you connect negative cable to battery, or to the negative stud on passenger side of hood?

Any codes set when you run the winch?

asilverblazer · February 9, 2023

6 hours ago, Hagar68 said:

Did you connect negative cable to battery, or to the negative stud on passenger side of hood?

Any codes set when you run the winch?

Battery, there was a ground stud nearby - it all goes back to the battery so that's where I went.

No codes.

I bought 25' cables and it took essentially all of it to go from the battery to the back. I had to buy more to go from the battery to the front (and made another set of jumper cables with the left overs).

Dr1ft3r · February 10, 2023

It all comes down to the duty cycle. If you are constantly using your winch at maximum load (400 amps?), then it's not going to take long before you kill your battery and/or your alternator.

An 80 amp hour battery is just that. It will provide 80 amps for 1 hour, or 160 amps for 30 minutes, etc. However, stock lead acid batteries are not designed to be discharged below 50%. That means it's really only a 40 amp hour battery. At 400 amps that gives about 6 minutes of usage.

The alternator will be providing some of that amperage as well, which will help the battery. The amount of amps provided by the alternator will be determined by its rpm. But it will never provide it's full rated amount to the winch because there are other electronics in the truck drawing current as well.

Anyway, in most cases the winch will likely not be drawing the maximum amperage. But repeatedly draining the battery to 50% charge will cause it to fail sooner than normal and overtaxing the alternator by often forcing it to recharge deeply discharged batteries will also cause it to fail sooner. How soon? That depends on the duty cycle and on how well they were built.

This is why I had the 220 amp alternator installed in my truck (versus the 170 amp alternator) and also why I will be adding a 2nd battery for my 15k winch thar draws 460 amps at maximum load. It should last longer than the 170 amp alternator and help keep the batteries from discharging nearly as much.

Dr1ft3r · April 11, 2023

Now that I've started planning my winch installation I have given this a lot of thought. I have decided to install another battery in the auxiliary battery location and run the winch off of that. However, it will be completely isolated from the primary system. I will keep it charged with a 40A dc-dc charger, most likely from Redarc, along with a nice Odyssey AGM battery. A good AGM battery will provide enough power to winch at max load for 15+ minutes, which is also most likely more than the duty cycle of the winch. (The charger is still supplying 40A of power at this time as well).

This way the primary system will never be subjected to 400+ amp loads from the winch (500+ amp loads max with my 16.5k Warn winch under full load, which will never happen to me... snatch blocks are your friend...). The primary system may or may not be able to handle it, but why take the chance? I know it can handle 50 amp loads with no problem. I have the snow plow prep package and a snow plow can draw up to around 200 amps on it's own.

The downside is if the winch needs to be used a lot in a short period of time then the battery may run out of juice. But with a 40A charger the battery should be able to be charged from empty to full in about 2.5 hours. So the drain would have to be significant to run out of juice. But if it becomes a potential issue, the battery bank can be doubled by using 2 batteries in parallel.

I may upgrade to the Redarc 50A charger instead. I'm still on the fence.

Be sure to research your batteries if you go this route. Some AGM batteries around this size (100 AH) may not be able to handle charging at this rate. Odyssey batteries require a 40A charger at the minimum for cyclic operations. Using a battery to power a winch this way is certainly considered a cyclic operation.

Some AGM batteries cannot be deeply discharged either (i.e. below 50% capacity). Be sure to use batteries that can be discharged to 80%+.

I would not use LiFep04 (Lithium Iron Phosphate) batteries under the hood, they can't handle the heat nor the cold (but otherwise would be ideal). The Odyssey batteries I'm looking at are rated for temps between -40 and 176F.

The Redarc chargers are rated for 14 to 175F. So if it's too cold the charger will stop, but the battery will still work. I'm more concerned with heat as the engine bay should be warmer than outside temps when the engine is hot. The Redarc chargers are also waterproof, dustproof, etc... as they are completely sealed and are used on vehicles that go under water while overlanding.

Clearly this route is more expensive than running the winch off of the primary system. But I believe that you will get what you pay for.

Edited April 12, 2023 by Dr1ft3r

Hagar68 · April 12, 2023

Thanks for your updated thoughts Dr1ft3r. I also had decided to stay segregated. I currently just have 2 big traditional batteries in the bed and tie them together but separate from the truck and keep them AC charged at the house (I'm don't keep the receiver winch on the truck except when it might be needed). The DC/DC charger is a really good idea to get on-board charging while protecting the truck systems.

I would love to have a bigger alternator or even the 2 on the snow plow pkg, but you don't find many of those options here in the south.

Dr1ft3r · April 12, 2023

19 hours ago, Hagar68 said:

Thanks for your updated thoughts Dr1ft3r. I also had decided to stay segregated. I currently just have 2 big traditional batteries in the bed and tie them together but separate from the truck and keep them AC charged at the house (I'm don't keep the receiver winch on the truck except when it might be needed). The DC/DC charger is a really good idea to get on-board charging while protecting the truck systems.

I would love to have a bigger alternator or even the 2 on the snow plow pkg, but you don't find many of those options here in the south.

It's no problem. I'm happy to help. There's not much info on this stuff to be found here on these forums. I don't know everything, but I'm happy to share what I know.

If that method works for you then there's nothing wrong with that route either. Some people do that for winches they keep on their trailers. Some also run a dc-dc charger for the winch batteries on their trailers or even for their campers (which is where I go the idea). At some point I may mount a winch in the front of the bed of my truck as well and run it off of the aux battery bank I already have for the front winch.

I had also considered a battery isolator, but there are other issues that arise in that situation. Such as issues with properly charging both battery banks (starter and aux). Plus, with a dc-dc charger the amperage from the alternator is controlled and kept low. I believe this is better for the alternator in the long run. Not to mention that with a charger the proper charge profile can be selected for the aux battery being used to ensure that it is charged properly, which will give the battery it's best chance for a long life.

Running 2 batteries in parallel, such as how they come from factory, would be a better route than an isolator. But that doesn't solve the problem of high amp loads on the system and both batteries would have to be identical in every way, including level of charge when installed (preferably both be charged to 100%).

I much prefer to keep my power sources separated.

Edit: I was just reading up on battery separators. Those are another option that may work for some people. They have certain advantages and disadvantages over isolators and parallel options. I still prefer the dc-dc charger method for this situation though.

Edited April 12, 2023 by Dr1ft3r