Larger Alternator for Cummins QSB 380

[Brent Thorkelson]

Hello

We have just installed 500 ah of lithium batteries along with a Wakespeed500 external regulator. Our alternator was checked and found to be in excellent condition when shop removed the internal regulator. We are considering changing the alternator which has the small 2″ mount (19si) we believe to a Delco 24si or 28si. I have attached some pictures for clarification.

SN on the QSB 380 is 46560020

The thought is we will need the j180 mount and appropriate arm. Change over the pulley from the original alternator to the new one, and have the internal regulator removed.

Any guidance would be appreciated.

Brent

Topic

[Clark Leighs]

I have a different engine  the old Cummins V555  so  the 28 would have fit.    I just didn’t need it so went with the 24.    Now I am sort of kicking myself.   Not hard but still I should have done some more checking.    

THe max temp would have been worth it but I won’t change now unless I burn the 24.

 

[Brent Thorkelson]

This is helpful Gene. Good to know the differences in the sizing.  <br />W I’ll confirm this. <br /><br />

Brent

[Gene Fuller]

I considered the 28SI instead of the 24SI. I do not remember all the reasons I chose the 24, but I did not really need more than 160 amp capacity. I do not have lithium batteries either.

 

The main heavy connections are not a problem for the 24SI. They are both easily accessible on the non-engine side of the alternator. The connections that are somewhat buried in the oil filter plumbing are for the remote sense, lamp, tachometer, etc. Since you are having the internal regulator removed I have no idea what wires will be used. However, I expect they would exit the case at the same location.

 

The 24SI is a little bit larger than the 19SI, but it fits without problem. I believe the 28SI is the same size as the 24SI, but I would certainly verify that if you decide to “go big”.

 

Gene

[Brent Thorkelson]

Clark<br />Biggest question I have right now is whether or not the 28si will fit from a size perspective. <br />Not sure if you also have the remote oil filter lines that you had to contend with. <br />maybe a person could modify the lines to make more room. <br />can’t move the filter back to its original location as I installed an Amsoil 2 micron remote oil filter so the space is already taken up. <br /><br />

Brent

[Brent Thorkelson]

Tony

Thanks for the link. I searched through them and couldn’t find anything relevant. Would like to see a diagram of measurements to compare the 19 to the 24 to the 28si so that I can be confident that the choice I make will fit. <br /><br />

Brent

[Brent Thorkelson]

Gene

Thanks for the response. The 24si seems to be the easier choice rather than the 28si. I do have the remote oil filter lines that run to the filters at the front of the engine. <br />Do you have the same set up. <br />Also we have 2.0 cables ( positive and negative) running directly from the alternator to the house lithium’s with an ACR. Fitting the cables to the new alternator might be a challenge. 

Thoughts

Brent

[Clark Leighs]

Take a look at the $ difference between the 24SI    AND THE 28SI  

I too changed my older 22SI to a 24 SI.   last year.    THe 24 has a higher temp rating than the 22.

It is fine BUT the 28SI has a higher temperature rating then the 24SI by about 50 oF.    If you are charging Li batteries that means you can set the alternator regulator to allow the alternator to operate as a higher output without cooking the alternator.       Take a good look at the spec. sheets.     

 

NOt turn the amperage up   but simply allow the alternator to operate at a high temp than the 24 which will still mean in most cases a faster recharge. 

[Tony Athens]

QSB 5.9 Large Frame Alternator Mounting

Pic attached……………

[Gene Fuller]

I made a switch from an old and failing 19SI to a 24SI about a year ago on my engine that is just a few serial numbers lower than yours. The new mount and arm are needed, but they fit right onto the existing engine mounting locations. Very easy.

 

The only wrinkle I found was that the secondary connections to the new alternator are deeply buried in the area of the remote oil filter plumbing. The 19SI had those connections on the side away from the engine while the 24SI moved the connections to the engine side. It is only a one-time hassle.

 

I also needed to change the end lug on the main output cable because the bolt on the alternator was a different size. The secondary connections are also different, but since you are going to a different regulator scheme a change will be required in any case.

 

The new alternator starts charging at idle, and it has worked great for the past year.

 

Gene

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Tony Athens

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