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Discussion Starter · #1 ·
Looking to upgrade my wimpy 100amp alternator. I don't think I need the dual set-up, and it seems a bit pricey. Just something to help out while plowing this winter and to run my 1500 watt inverter that I occasionally use.

What's the rating on the one that comes with the snow plow package? I feel like its 145amp?? Where's a good place to find a deal on a 145-160amp alternator?


91 Posts

My Sierra 2003 2500HD D/A has the snow plow prep package and comes standard with a 145 amp alternator. Which is


89 Posts

You may want to check a company called AlterStart. I purchased a new 2nd alternator for my dual setup from them. They are very knowledgeable about correct applications and can custom build heavy duty alternators to you specifications.



334 Posts
I finally got around to installing my new dual PowerMaster Alternators. I wanted to pass along some installation tips as well as posting photos of the finished results.

In the beginning I did several searches for this mod. I only found one or two posts on the internet that really went over the installation of the dual alt mod. mdrag really help with his insight. I first want to post the correct part numbers and the newest part numbers for the serpentine belts that are available. There is a Service Bulletin that was issued by GM in regards to the belts sizes and the squeaks associated with this factory or aftermarket modification.

Here are the part #'s needed for 6.6L Duramax trucks:

1) Second alt bracket: 97212348 approx $45
2) Idler pulley: 97233352 approx $10
3) Idler pulley bolt: 11515769 approx $3
4) Alt upper mounting bolt: 94009975 approx $2
5) New Bracket to engine bolt 94009975 approx $2
6) Alt lower mounting to engine bolt 11516360 $1.50
7) Micro-pak terminals: 12084913 (for position C1-32 on the ECU - charge
indicator control 01-03)
8) Alt 4 position connector (for use with OEM alternators only) 15306071 approx $10
9) Fusible link for alt output 15321209 approx $13

***NOTE*** Part# 94009975 bolt is for
quantity TEN bolts, only TWO are needed.

For Serpentine Belt #’s and proper lengths please refer to the GM TSB below

When installing either one or two PowerMaster Alternators you will need to get different connectors to control the alternators. These are available at any part store under the Help/Motormite name or as a Dorman’s part#.

4-Wire GM Voltage Regulator Module:

Dorman Part # 643-123

Help/Motormite Part # 85118

OEM Alternators available:

AD230 46A 105amp #10464438
AD244 67A 130amp #10464453

PowerMaster Alternators Used

PowerMaster Part # 48202 (2)

When installing two PowerMaster Alternators you will need to modify the EGR coolant line behind the primary OEM Alternator by bending it in an upside-down “U” shape to allow proper clearance. It is time consuming but it can be done.

It is also recommended that the power cables from the alternators to the power block be upgraded with a thicker wire. I have not done this yet due to time constraints. But it will be done and posted here as soon as it is completed.

After all was said and done I did some tests on the new installation and here are my conclusions:

Major amperage improvement to the electrical system at idle. We went from 35-40 amps at idle with OEM alternator to well over 115 amps at idle.

The lights are WAY brighter at any engine speed with any load on the system

Major COOL factor when I pop the hood to show off the new alternators.

Found the secondary alternator rarely comes on unless a HUGE load is placed on the batteries. (We had the load machine smoking to get the 2nd alt to work) this just means I have a killer back up unit waiting to be used.

I hope all of this information is useful to you all. Please feel free to post any questions or comments about the installation and I will be happy to assist you with you mod.

Click on the photos below for larger images

<A href="http://members.cox.net/ssmoky/dscn1927.JPG" target="_blank"> <IMG
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