Our new truck (picked out from inventory) has dual Alternators and Batteries. I imagine it was intended for a big travel trailer or something.

Seems a bit gratuitous for our use: Towing a race car on a flat bed trailer.

I wonder if I should remove the extra battery and alternator and go to one.

Thoughts?

Thanks,
Russ

What kind of truck please.

I would leave the batteries alone, they are on there for the extra cranking amps needed for diesel motor..

I don't see where it's hurting anything I'd just leave it alone honestly.
The dual batteries are for Cold Cranking Amperage in COLD weather, I dont think i need two in California but better safe than sorry.

What kind of truck please.

Sorry... '08 LMM 2500HD CC/SB

I would leave the batteries alone, they are on there for the extra cranking amps needed for diesel motor..

Ah... This is our first Diesel truck. So all GM Diesel pickups get dual batteries?

Thanks,
Russ

Ah... This is our first Diesel truck. So all GM Diesel pickups get dual batteries?

Thanks,
Russ


Yup. The diesel has mods that gas engines don't. They have glow plugs (you should see the indicator on the dash when you first start the truck for the day), and for best starting, wait until the light goes off then have at it. Next, you also have an air heater in the intake to warm incomming air - again for starting purposes. Last, these engines run somewhere around 22:1 compression ratio, so you need extra ummph (a technical term) to crank them over.

The extra alternator is needed more for campers or snow plowers.

Welcome to world of diesel.

Yup. The diesel has mods that gas engines don't. They have glow plugs (you should see the indicator on the dash when you first start the truck for the day), and for best starting, wait until the light goes off then have at it. Next, you also have an air heater in the intake to warm incomming air - again for starting purposes. Last, these engines run somewhere around 22:1 compression ratio, so you need extra ummph (a technical term) to crank them over.

The extra alternator is needed more for campers or snow plowers.

Welcome to world of diesel.
6.2 and 6.5 run 22:1 dmaz run no higher than 17.5

6.2 and 6.5 run 22:1 dmaz run no higher than 17.5

Thanks. Still higher than gas though....

In cold weather you will need all the cranking power that the 2nd battery will give you to run the glow-plugs, the intake air heater and cold start that diesel. The 2nd alternator will come in handy for campers, travel trailers, snowplows, and any extra electrical accessories you might end up installing.

Compression Ratio for 2001-04 LB7 & 2004.5-05 LLY = 17.5:1
Compression Ratio for 2006 LLY/LBZ & 2007-08 LMM = 16.8:1

Still a lot higher than gassers.:)

Sorry... '08 LMM 2500HD CC/SB

Enter your truck info in your signature when you get chance. That way you won't be constantly asked what kind of truck you have.

BTW - Welcome to the Diesel Place. :)

Ah... This is our first Diesel truck. So all GM Diesel pickups get dual batteries?

Thanks,
RussYes...and Fords and Dodges too.

Do you have a winch on that trailer for the car when it gets FUBAR'd at the track? Second alternator would be real handy to have with a winch. I ran a seperate harness from the front batteries to the rear bumper with quick connects to power the battery and winch on my car trailer.

My truck only has one alternator! The one I test drove had two. Should I upgrade and buy an extra alternator for my truck?????? I dont really pull anything!

There are 2 options on alternators from GM you either get 1-145 amp or 2-105 amp. I prefer to have 1 rather than 2 because if one starts to go bad it will kill the other and then you end up buying 2 instead of 1. Just my .02.

Sweeet that makes since! I thought about this the other day,but yes your right!

woodchuck2: I do have a winch on the trailer. I ran 4 or 6 gauge wire from the battery to the rear bumper of the old truck, much like you did. Luckily, I removed the cabling, fuse and plugs from the old truck before trading it in. Probably $100+ worth of stuff.

The old truck had a couple nice posts at the fuse panel (one powered, the other fused when the big fuse was bolted in) that I placed an OEM 80amp fuse into and ran the wire from the fused post. Unfortunately, it looks like they changed the configuration. Now, there are still 2 posts, closer together and both powered. Not sure if they are fused, and even if they are, I'm sure they're not 80amps. Maybe I'll run directly to a battery with an 80amp inline fuse.

Tubbz71: sounds like you're fine unless you're running a bunch of extra power drawing equipment.

Russ

I'm hoping that this will help with the audio system in my truck.

There are 2 options on alternators from GM you either get 1-145 amp or 2-105 amp.

The K76 option (dual alternator) on the LMM gives you 2 125Amp alternators - more power good !

Ah... This is our first Diesel truck. So all GM Diesel pickups get dual batteries?

Thanks,
Russ
Dodge and Ford diesels all have dual batteries too - becasue of the high compression cranking needs of diesels.

I was wondering how one going out would kill the other are they in a series or ?? I just don't know not trying to be a wise arse lol.;)

There are 2 options on alternators from GM you either get 1-145 amp or 2-105 amp. I prefer to have 1 rather than 2 because if one starts to go bad it will kill the other and then you end up buying 2 instead of 1. Just my .02.

Ender, Let me know if you wanna sell the second alternator. i have airbag compressors , air horns and a huge stereo system and could use the second alternator. Also, can anyone tell me what I need to do on the wiring to upgrade my truck to a dual alternator setup? Someone said the RPO code was K65 but had no part numbers. I have the numbers for the alternator and the bracket and the belt, just cannot seem to find the part number for the harness. The parts guy at the GM counter is trying to say that I have to put a whole new motor harness in my truck, which sounds lame..Any help.Thank you

I installed a second alt on my LMM a couple months ago. Very simple. Tomorrow or the weekend I will list all the PNs and how it's done, if anyone would like the info.

Thanks Greatbear. I have 2 friends at the parts counter at a Chevy dealership and neither seems to know how to add the second alternator without a whole new engine harness for $500..The second alternator is only $159..??..I was thinking of tapping into the 2 wires from the first alternator and running the power to my fusebox on the firewall. i looked at a truck today with dual alternators and I found where the power goes on the fusebox..If you can list those part numbers it would be very helpfull..Yuo would think that chevy would get with the program and allow easy upgrades and add ons..

The 07 6.0 gassers have 2 batteries in them also. nephews 6.0 has them.
Dont know if all 6.0 do, or what options on the truck requires duel batteries.

what is the option code for 1 alternator on the new LMM's??? thanks

If you have 2 alternators you ought to leave it alone...there is a bunch of wiring that you will somehow have to bypass or remove.

The alternators are paralell. The second only comes on if told to do so by the BCM under a load. otherwise, the first is the worker. IIRC.

To put a second alternator in without breaking the bank, Merchant Auto (A vendor here) has a kit...I am pretty sure kennedy does too, and there is a write up in the DIY forum that you could look up.

We've decided to keep the dual alternator setup... a bit of extra weight on a 7000lb rig is worth the extra capacity if we ever need it.

Thanks,
Russ