Second battery connection for winch install

jderbabian · April 21, 2022

I have installed a second battery for use for only my winch. I made up the cables and purchased an isolator. My question is about the hookup to the primary battery. I removed the cover from the primary battery and was astounded by the mess of plates, terminals, and other stuff there (far different than my 09 2500HD DMAX). I have been researching where to connect my second battery to and really have not found anything on the topic. I have seen several videos where people have installed a 'snow plow' terminal post with a 200amp fuse off one of the existing posts. I cannot find any info on this post/terminal or the 'Little Fuse' and my dealer is no help. Can someone provide info or part numbers for these two items? The pic is taken from a video I saw and the parts I am looking for are in the yellow circle. Pic 2 is where I have it hooked up for now so I can keep the second battery charged.

Another JR · April 21, 2022

I have a 2021 3500hd gas truck with the second battery from the factory. I assume your truck is gas or it would have had the second battery for starting.

That 200 amp fuse you have circled is present but unused on my truck. I believe that fuse, the 60 amp fuse next to it, and the associated bus bar were part of the upfitter switch kit that I ordered with the truck. I have not done the full installation to connect the switches, but i believe i installed those pieces on the battery shortly after i took delivery.

My truck’s wire to the aux battery has a 100 amp fuse at each end. Here are pictures of the main and aux battery fuse blocks. Everything is stock except for the connection to the main battery via the 80 amp fuse with the red shrink tube and the upfitter switch fuses. That red wire goes to the dc to dc charger in my camper.

Edited April 21, 2022 by Another JR

Another JR · April 21, 2022

I’d suggest putting fuses on that temporary wire at each battery. The consequences of a hot short if either end is not fused could be a fire.

I can provide my VIN to help you search for parts if you decide you want to replicate the factory configuration.

Edited April 21, 2022 by Another JR

jderbabian · April 22, 2022

That would be great Jon. You can send it to my email: [email protected]

Thanks!

John

Another JR · April 22, 2022

6 hours ago, jderbabian said:

That would be great Jon. You can send it to my email: [email protected]

Thanks!

John

The VIN is in this photo of my weight stickers.

The more I think about it the more certain I am that those fuses were added by me as part of the upfitter switch kit of parts. The 60 amp fuse is for direct wiring to the kit’s relay box and the 200 amp fuse is for supplying any larger load passing through a separate user supplied large relay controlled by an upfitter switch. I don’t know if they sell just those fuse block parts separately.

gemarsh · April 23, 2022

GM upfitter switch fuse kit...

https://www.ebay.com/itm/154570859174?fits=Year%3A2020|Make%3AGMC&hash=item23fd2422a6:g:KeEAAOSwlg9hGZY0

Another JR · April 23, 2022

42 minutes ago, gemarsh said:

GM upfitter switch fuse kit...

https://www.ebay.com/itm/154570859174?fits=Year%3A2020|Make%3AGMC&hash=item23fd2422a6:g:KeEAAOSwlg9hGZY0

He’s going to be happy you tracked that down. I think it’s exactly what he’s looking for. Nice job.

jderbabian · April 23, 2022

Awesome - Thanks all, I ordered the fuse kit.

mobilelists · April 23, 2022

This discussion has been very helpful.

So if I understand correctly, the 200 amp circuit has no electrical connection to the 5 upfitter switches. The upfitter switches are accessed through the added installed internal fuse box when the upfitter kit is installed. And to use the 200 amp connection one should connect to it to an external relay (say a BlueSea 9012) that could be controlled by powering it's coil through an upfitter switch by connecting it's coil to the fuse for that switch in that internal fuse box.

Edited April 23, 2022 by mobilelists

jderbabian · April 23, 2022

My understanding is the post with the 200amp fuse is originally intended for the snow plow option. I'm going to use it to power a winch. My aux battery will be wired to it with a isolator between batteries.

Another JR · April 23, 2022

9 hours ago, mobilelists said:

This discussion has been very helpful.

So if I understand correctly, the 200 amp circuit has no electrical connection to the 5 upfitter switches. The upfitter switches are accessed through the added installed internal fuse box when the upfitter kit is installed. And to use the 200 amp connection one should connect to it to an external relay (say a BlueSea 9012) that could be controlled by powering it's coil through an upfitter switch by connecting it's coil to the fuse for that switch in that internal fuse box.

The upfitter switches, when all wired up, control relays in a relay pack that you install under the dash. You would connect your loads to the connector from that relay pack. That relay pack gets power from a wire that is connected to the 60 amp fuse that is near the 200 amp fuse. The upfitter switch relays are only rated for 20 or 30 amps (I think 3 are 20 amp and 2 are 30 amp). If you want to switch and power anything that draws more current than the kit relay can handle, you would use the upfitter circuit to in turn control a user supplied larger relay on a user supplied wire from the battery. Don’t forget to install an appropriate fuse at that big battery connection if you do that.

Edited April 23, 2022 by Another JR

DWM NM · May 26, 2022

I am installing a 12000 lb electric winch on my 2020 Chev Silverado 3500 HD. The winch reportedly could draw up to 300 amps for a short time under maximum load. In looking at the battery distribution panel in the battery compartment i see a terminal marked 500 A. My winch came with a circuit breaker (rating unknown) that presumably would be in the 300 A range. i would like to run a battery lead off that 500 A terminal to my circuit breaker. There seems to be no other terminal rated above 200 A. Any comments on this idea would be appreciated.

Also, I have not found any wiring information regarding the factory second battery and its purpose. I assume it is auxiliary for starting my big diesel. I would like to be able to use both batteries to run the winch when needed but, not risk ending up with both batteries dead and not being able to start my truck. Your thoughts are appreciated. Thanks, Don

Another JR · May 26, 2022

If you have a diesel then your batteries are wired in parallel with no isolator. You are correct that the two batteries are required for sufficient starting current. I have not looked at the battery fuse blocks on a diesel, but my guess is the 500 amp fuse is the main connection between the two batteries. Just a guess, though.

mobilelists · June 7, 2022

I have the upfitter switches installed and working. Now I am trying to figure out how best to fasten a t-fuse holder and a relay in the engine compartment. From there to the truck bed is not a problem.

Which locations and mounting methods have worked best for other? I am using a Blue Sea Systems 5502 Class T Fuse Block and relay.

Thanks