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2025 chevy 2500hd 6.6 gas crew cab
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Joined: May 2025
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2025 chevy 2500hd 6.6 gas crew cab
Question. This truck has a secondary battery compartment. I went to 3 dealers to ad a second battery in parallel to give more starting power etc. All dealers tell me they do not know how. All upfitters will not also. Chevrolet says the dealers has to do the work or the warranty Will be void. Even calling in to adviser unable to find info. But I have a wiring kit for a plow. Can anyone give me input. I want 2 batteries for more power to start up
Thread Starter
Junior Member
Joined: May 2025
Posts: 2
Likes: 1
2025 chevy 2500hd 6.6 gas crew cab
Question. This truck has a secondary battery compartment. I went to 3 dealers to ad a second battery in parallel to give more starting power etc. All dealers tell me they do not know how. All upfitters will not also. Chevrolet says the dealers has to do the work or the warranty Will be void. Even calling in to adviser unable to find info. But I have a wiring kit for a plow. Can anyone give me input. I want 2 batteries for more power to start up
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True Car Nut
Joined: Feb 2015
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From: Earth
There was technically no question. 
Yes, for the diesel.
I can't see a good reason for this for starting power. It will start fine on one battery. The "etc." might need a second battery though.
Dealerships are not usually good at custom work besides the odd dealer that will do lifts and big tires and stuff like that.
I can see why: They don't want any liability for breaking your brand new truck and they likely don't have an exact diagram and procedure blessed by corporate'* risk-management department.
This is not true. They commonly say this though. The Magnussen Moss Warranty Act covers this. If your modifications cause an issue, that won't be covered by warranty.
Like a service adviser at a dealership? Yeah they're likely never going to know how to do this.
How is this related to starting?
I'd use the second battery just for the plow. If you do insist on having two batteries for starting, they need to be the same exact make/model/age as each other. This job would have them wired in parallel, not in series. You're talking about custom electrical work on a brand new vehicle filled with electronics. Be careful with whatever you do.
I can't see a good reason for this for starting power. It will start fine on one battery.
Yes, for the diesel.
Dealerships are not usually good at custom work besides the odd dealer that will do lifts and big tires and stuff like that.
I can see why: They don't want any liability for breaking your brand new truck and they likely don't have an exact diagram and procedure blessed by corporate'* risk-management department.
Like a service adviser at a dealership? Yeah they're likely never going to know how to do this.
How is this related to starting?
I'd use the second battery just for the plow. If you do insist on having two batteries for starting, they need to be the same exact make/model/age as each other. This job would have them wired in parallel, not in series. You're talking about custom electrical work on a brand new vehicle filled with electronics. Be careful with whatever you do.
I can't see a good reason for this for starting power. It will start fine on one battery.
Last edited by CathedralCub; May 3, 2025 at 02:41 AM. Reason: Exchanged a space for an apostrophe
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