Passing on some info about second battery option.

64BAwagon · September 18, 2023

I opted for the 2nd battery ($135) along with the 220a alternator ($150) on my 2024 3500 L8T gas truck. When I got it I noted that there were a couple of relays on the side of the battery as well as a bus bar and fuses on the top. It was much more than just another battery connected to the main one. I was told yesterday that the components on the 2nd battery are actually part of whats included in the plow package. The system will sense a large power draw from something like a hydraulic pump on the plow and then puts the alternator into a full output mode rather than shutting it off when the battery is charged and the load is low. This apparently prevents the system from having large loads placed on it when its in low consumption mode.

I bought this option because this truck is used mostly for towing and I wanted extra capacity since the trailer increases the 12v demand. For the money it was a worthwhile option but now I have the added value if/when I sell it and it can easily be used for a plow truck. (it also has the "camper" heavier front torsion bars)

kf9yr · September 18, 2023

If you buy part # 84669070 it comes with the fuses that connect to the bus as well as the fasteners that are fit for the 2nd battery tray.

Makes it easy to connect high amperage cables.

Dunn · September 20, 2023

Well worth the money....if I ordered one 100% I would get it, I usually buy off the lot and rarely do you find them

64BAwagon · September 20, 2023

Thats one of the reasons I like to order mine. I get all the options I want and none of the ones I dont want.

Ausslo · September 20, 2023

On 9/18/2023 at 12:35 PM, kf9yr said:

If you buy part # 84669070 it comes with the fuses that connect to the bus as well as the fasteners that are fit for the 2nd battery tray.

Makes it easy to connect high amperage cables.

That kit is actually a plug and play for the primary fuse block though you could use it on the auxiliary block with some modifications. I just installed it on mine.

Another JR · September 21, 2023

Part of the assembly that comes on top of the second battery in a gas truck is a battery isolator. Loads you connect to the aux battery are isolated from the starting battery when the truck isn’t running so they won’t deplete your starting battery. This is different from the diesel, which has the batteries directly connected at all times because they both are needed for starting.

Ausslo · September 22, 2023

On 9/20/2023 at 3:50 PM, Ausslo said:

That kit is actually a plug and play for the primary fuse block though you could use it on the auxiliary block with some modifications. I just installed it on mine.

GMC4Zee · September 25, 2023

I have plow option but be aware that it also includes the striffer front springs which does affect the ride somewhat. I did get the dual batteries also.Harness was included with the option.

revrnd · January 16, 2025

On 9/20/2023 at 10:29 PM, Another JR said:

Part of the assembly that comes on top of the second battery in a gas truck is a battery isolator. Loads you connect to the aux battery are isolated from the starting battery when the truck isn’t running so they won’t deplete your starting battery. This is different from the diesel, which has the batteries directly connected at all times because they both are needed for starting.

That's what my brother & I have been trying to figure out since I got my 2024 L8T w/o the plow prep. I've had 5 gassers GMT400 & up w/ the VYU, but none of them had an auxiliary battery.

revrnd · January 16, 2025

On 9/25/2023 at 9:14 AM, GMC4Zee said:

I have plow option but be aware that it also includes the striffer front springs which does affect the ride somewhat. I did get the dual batteries also.Harness was included with the option.

Having been around 3/4 tons since the 70s, I hadn't really noticed the stiffer front suspension on them. Seldom have I driven a 1/2 ton. I have driven my brother's 3/4 ton Dmaxes, that is a different story though.

T Slave · January 22, 2025

I ordered my 2022 with 2nd battery plow truck package, thought it was a great buy for extra battery and 220 amp charging system. I put the front 10,000 lbs. receiver hitch on the front to be able to put my winch in and made a bull bar with lights to go in when winch is not being used. Installed quick connect plug like on fork truck battery chargers on truck and winch. Just load the winch in receiver plug into truck and ready to use. I have a 13,500 lbs. winch pulls great. Though one day I might get one of them Home Plows for the driveway in the winter. It's got a stiffer front suspension than my older 1 ton had but not all that bad.

gemarsh · January 23, 2025

12 hours ago, T Slave said:

I ordered my 2022 with 2nd battery plow truck package, thought it was a great buy for extra battery and 220 amp charging system. I put the front 10,000 lbs. receiver hitch on the front to be able to put my winch in and made a bull bar with lights to go in when winch is not being used. Installed quick connect plug like on fork truck battery chargers on truck and winch. Just load the winch in receiver plug into truck and ready to use. I have a 13,500 lbs. winch pulls great. Though one day I might get one of them Home Plows for the driveway in the winter. It's got a stiffer front suspension than my older 1 ton had but not all that bad.

I'd love to see the bull bar setup!

T Slave · January 28, 2025

Here you go. Little dirty from the winter roads.

3500L8T · February 13, 2025

I have the same factory option dual battery in my 2021 Silverado 3500 Gas L8T. I would like to know if there is any isolation between the two batteries so that when the auxiliary battery starts to drain it does not affect the first battery. Or do both batteries just charge and discharge equally with no protection in between?

Edited February 13, 2025 by 3500L8T

Another JR · February 13, 2025

26 minutes ago, 3500L8T said:

I have the same factory option dual battery in my 2021 Silverado 3500 Gas L8T. I would like to know if there is any isolation between the two batteries so that when the auxiliary battery starts to drain it does not affect the first battery. Or do both batteries just charge and discharge equally with no protection in between?

See my September 20 post up above in this string. Yes there is an isolator. I have a 2021 3500 gas truck with dual batteries and 220 amp alternator.