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Dual Alternators

5K views 13 replies 10 participants last post by  nutdriver 
#1 · (Edited by Moderator)
I am very new to the diesel world. Just purchased a 2019 3500 (High Country) SRW. It came with dual alternators. I pull a Reflection 303. What is the advantage ( if any) to having dual alternators?
 
#3 ·
I ordered my 2018 with dual alternators. I snow plow and have a 9.5' Fisher plow which is why I went with two alternators. These larger plows are quite demanding on the electrical system. I don't see many ordered with two.
 
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#4 ·
The funny thing is that almost all mid trim and up F250’s are ordered with them. I think the reason is that most F250’s are seen as a more work oriented truck. I can tell you from personal experience they are more setup for work type use but they are not as comfortable to drive on a day to day basis. This is my first GMC and love it but it does have short comings if your looking for a dedicated work truck. I decided on comfort this go around and glad I did.


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#5 ·
Dual alternators have the ability to handle a much higher electrical load like snow plows, winches, etc. If you were to run a larger size wire to your trailer, it would help charge your batteries faster or if you find your batteries need a fast charge when dry camping, hook up your truck to the trailer batteries with a heavy duty set of jumper cables and you will be able to charge your trailer batteries quickly.
 
#6 ·
Alternators are not as efficient at lower engine speeds. Having two allows you two recover power faster when running high-amp draw accessories like a plow, spreaders, winches, compressors, etc., basically things that are used at low engine speeds or even at idle. Since it is highly unlikely you are charging your RV batteries with your truck, having two alternators has no advantage for you.
 
#7 ·
The alternator capacities being installed in these trucks has increased greatly over the years.

FWIW, the currently offered combinations are:
Standard - 150A
Optional - 220A (included with snowplow prep on gas or diesel)
Optional duals - one of each (and only available on dmax)
 
#8 ·
I agree, but I don’t know what the longevity of the higher amp alternator would be, it must be harder on the bearings.
 
#9 · (Edited)
Bearings are available in lots of sizes, load ratings and speed ratings.

I'd expect the alternator designer and belt drive designer(s) to have done their homework.
In the '80's when I was designing belt drives and picking bearings for equipment the OEM also tested the design to be sure I didn't miss something....
 
#10 ·
So your saying that Nick has 370 amps of charging capacity available to him, wow. I’m not even close with my lowly 145 amp. Almost sounds like you could blow something up, like in a racing engine for example.
 
#11 ·
Yes, and no. Amp ratings for alternators are peak at ideal temps and speed. At idle or there abouts they put out about half. So a plow rig with duals could produce as much 180 amps. A plow or winch can easily draw more than that, so lifting a plow for example may pull the max the alternators can put out plus a little from the batteries, but having the large capacity will fill the batteries back up in a hurry. No add in an array of lights, stereo and so on and you can see where it goes in a hurry.
 
#12 ·
�� Good info
 
#14 ·
My truck also has the dual alternator option. I am not planning to run a snow plow but will the dual alternator feature also provides some redundancy if one alternator failed. Is that a real benefit? Seems like that might depend on how the alternator fails?? For example, a bearing failure would not be saved by the second alternator.
 
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