Dual alternator conversion?

FirstAscent · September 23, 2020

Hey everyone,

So I know that you can get dual alternators from the factory, mine only has the single, does anyone know what is required to add a second alternator?

Is there an existing mounting point for it or does it require a bracket?

I’d imagine a longer belt and the actual alternator as well of course.

I’m looking into a not so normal scenario but want a 24v alternator that would charge some 24v lithium batteries completely independent of the truck, so I wouldn’t be tying this into the trucks electrical system whatsoever.

First step is to see what it would take to mount the alternator.

Oh and if anyone that sees this has the factory dual alternators, post up any photos of where they’re located, thanks!!

I have the duramax too btw.

September 23, 2020

On my 12 I added a second alt but used it too combine with the factory. The newer gm ones use the bcm to tell them when to charge. Yes I had to get bolts and a bracket, idler and longer belt. Also charge wires and i tied into the stock harness with a factory connector to make it charge.. your setup will be different... maybe easier to tie into the stock charging and use an adapter like milwaukee makes for power tools.

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Campthewestcoast · September 23, 2020

Look into redarc dc to dc chargers out of Austria they do a lot with 12 volt and 24volt systems for charging

I used dcbc1240 to charge my trailer batteries and run may 12 volt refrigerator while towing

Campthewestcoast · September 23, 2020

The problem with 2017 Silverado was the variable voltage alternator I needed full voltage from the alternator all the time to be able to charge my batteries to 100% and send 25 amps to my 12 volt refrigerator

I used the redarc dcbc1240s and also added solar panels to the travel trailer since I don’t have the option of running propane on the refrigerator while towing

Stand By · September 24, 2020

Not to hijack the thread, but similar concern, maybe brainstorming will help all of us. I have the 6.6 custom which has the 120 amp alt. At a minimum, I'm thinking of adding a dual purpose group 29 in the 2nd battery location for rec use or possibility of a plow down the road. I have a group 31 deep cell I could use, but probably wouldn't fit in the OEM location. Was planning on just running them together off the 120. Now, also wondering about adding the 2nd alternator to the engine. Thinking if an earlier version, not requiring input from the ecm could be added, then have it feed the second battery, independant of the primary system. Wondering if an earlier alternator case and pulley might fit in, or if a later one would have to be custom built to eliminate the need for a control module?

September 24, 2020

I added a DC power 270 xp. 270 amps max i think 200 at idle. When the computer turns on the factory both turn on and run... it works great. No complaints. I had a new charge wire made 2 Gauge (my bad thought 0 gauge but rated for the amps) but looks factory and added the on battery fuse panel. One alt is hooked up to each battery and with the factory line above the radiator together. I guess you could find an old one wire and run it... dc power can make anything you want... they even have 300amp and more... mine is the hairpin stator model. A local place can make them as well for less. I also have two new agms now... x2 power from batteries plus. Also added a larger ground from the engine.

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September 24, 2020

Group 48 in my dmax... two of them...

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redwngr · September 27, 2020

On 9/23/2020 at 8:34 PM, Stand By said:

Not to hijack the thread, but similar concern, maybe brainstorming will help all of us. I have the 6.6 custom which has the 120 amp alt. At a minimum, I'm thinking of adding a dual purpose group 29 in the 2nd battery location for rec use or possibility of a plow down the road. I have a group 31 deep cell I could use, but probably wouldn't fit in the OEM location. Was planning on just running them together off the 120. Now, also wondering about adding the 2nd alternator to the engine. Thinking if an earlier version, not requiring input from the ecm could be added, then have it feed the second battery, independant of the primary system. Wondering if an earlier alternator case and pulley might fit in, or if a later one would have to be custom built to eliminate the need for a control module?

They keep bumping up the size of standard and available alternators.

2020 HD's the standard alternator is 170A on gas, 220A on diesel (up from 150A standard on all HD engines in 2019)

KW7 Alternator, 170 amps
--- Requires (L8T) 6.6L V8 gas engine.

KW5 Alternator, 220 amps
Trims other than custom -- Included with (L5P) Duramax 6.6L Turbo-Diesel V8 engine or (VYU) Snow Plow Prep/Camper Package. Free flow on (L8T) 6.6L V8 gas engine.
On Custom - Included with (VYU) Snow Plow Prep/Camper Package.

KHF Alternators, dual, 220-amps primary, 170-amps auxiliary
On Trims other than custom - Requires (K4B) auxiliary battery with (L8T) 6.6L V8 gas engine.
On Custom - Requires (K4B) auxiliary battery.

September 27, 2020

Try these people. I used to live in Tucson but in phoenix now.... i used my 2012 as an example.

https://www.tucsonalternator.com/MPartDetails.aspx?IDNum=131964

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Stand By · October 1, 2020

On 9/27/2020 at 12:27 PM, redwngr said:

They keep bumping up the size of standard and available alternators.

2020 HD's the standard alternator is 170A on gas, 220A on diesel (up from 150A standard on all HD engines in 2019)

KW7   Alternator, 170 amps
--- Requires (L8T) 6.6L V8 gas engine.

KW5      Alternator, 220 amps
Trims other than custom -- Included with (L5P) Duramax 6.6L Turbo-Diesel V8 engine or (VYU) Snow Plow Prep/Camper Package. Free flow on (L8T) 6.6L V8 gas engine.
On Custom - Included with (VYU) Snow Plow Prep/Camper Package.

KHF      Alternators, dual, 220-amps primary, 170-amps auxiliary
On Trims other than custom - Requires (K4B) auxiliary battery with (L8T) 6.6L V8 gas engine.
On Custom - Requires (K4B) auxiliary battery.

Thanks for the correction. I meant I had the 220 since mine came with the plow prep.

FirstAscent · October 4, 2020

Thanks for all the comments so far everyone! I had to head out of turn for work and was crazy busy but back to normal life again. I’ll check out these options to see if I can make something work.

I know 24v alternators exist, and dual alternators on these trucks exist, so just need to find the right application for my project

TXGREEK · October 4, 2020

I too have been looking into adding a second battery and was recommended RedArc https://redarcelectronics.com/collections/in-vehicle-battery-chargers-isolators/bcdc1250d

I’d seriously look into these folks.

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Bigwalker · October 11, 2020

As mentioned previously give REDARC a look, sounds like the BCDC 2440 or 2450 would give you what you need with out adding a special alternator. These units are designed for modern variable voltage charging systems. So when your engine battery charge drops to a low voltage the bcdc keeps charging you Auxiliary batteries at A higher level to maintain a full charge, they also work with solar and shore power, and. An automatically switch and cover all battery types. You can mount the charger close to your li batteries and simply run a large gauge hot lead from your existing battery to the unit. I have used them on my other trucks for several years to solve the variable alternator issues when charging aux batteries. I will be installing one on my 2020 this winter.