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The truck I just got is on its 3rd alternator in a couple years according to previous owner, all have had diode failures causing the TC lock/unlock condition. Assuming that a quality high amp alternator is going to last longer than a over the counter replacement unit..

 

I was looking at nations alternators but the one for the 24v diesel looks to have a 2 pin plug on the back of it but mine has 2 ring terminal studs. Im new to dodge and cummins. What am I missing here? Does the 98 24v have one off parts or something??

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I think for 98s you have to call them, might not be on website. Sounds like something else is wrong though.

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The biggest killer for alternators is starting the truck on a cold morning and leaving just idle with the grid heater banging against the alternator. The alternator can't keep up and the idle speed is too slow to cool the diodes so they fail. Alternator failures are more common in the winter time than summer time hence from the cold start load on the batteries, 190 amp or 95 amp load of the grid heaters and idle speed that only gives partial charging ability. Even if you get a bigger alternator you still going to put a lot a stress on it if you continue the same habit.  

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This truck is new to me I haven’t even been able to put it in to service just a couple little drives to try to diagnose problems.

 

Winter temperatures around here generally stay above freezing except for maybe a couple cold snaps that are just below freezing. I’m thinking of just disconnecting the grid heater except for the odd cold snap I get here. Good idea or not?? 

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My grids are and have been disconnected going on 3 winters now. I typically see the temps you describe and dont have any issues. I do plug mine it on a timer to come about an hour before I leave when the temps get near 20f. The truck is happier starting and warning up then. It will start without plugging it in below that but it can be pretty angry at those temps. So in my opinion no harm no foul. 

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I could not agree more that the grids are hard on the alternator and AC noise output. That's why I put them on a switch. It get too cold here to do without. I turn them on to start the truck, then simply turn them off once it's running.

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That's why I like Mikes high idle switch, I always leave it on MPG mode theta way grids only cycle little bit and if it's cold out I turn it off and it's back to factory. I used a resistor with a relay for few years to do same thing but wanted something more simple and clean, it's very well made and I like it. But certainly if you leave in wormer climate disconnecting grids all together is the way to go.

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I do the same as @Dieselfuture. My truck doesn’t like the cold so typically when I see temps anywhere in the 30’s I plug the truck in, 40’s I’ll use factory grid cycling and anything else is always in MPG mode for minimal grid cycling.

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46 minutes ago, Dieselfuture said:

That's why I like Mikes high idle switch, I always leave it on MPG mode theta way grids only cycle little bit and if it's cold out I turn it off and it's back to factory. I used a resistor with a relay for few years to do same thing but wanted something more simple and clean, it's very well made and I like it. But certainly if you leave in wormer climate disconnecting grids all together is the way to go.

Interesting. I was under the impression that the battery temp. sensor had more to do with grid cycle than IAT and coolant temp.

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7 hours ago, dave110 said:

Interesting. I was under the impression that the battery temp. sensor had more to do with grid cycle than IAT and coolant temp.

Iat and ect take care of grids and 3/6 high idle. In summer grids only cycle for few seconds if you fool iat alone in winter it will only cycle few seconds also. 

Battery sensor is for volt regulator in pcm, colder it is more it charges.

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1 hour ago, Dieselfuture said:

Iat and ect take care of grids and 3/6 high idle.

 

Partially correct. Battery temp sensor also plays a roll in grid heater control. Take notice that both ECT could be 195*F and IAT above 100*F and still get grid heaters. This is because the last check is done against the battery temp sensor and if the temperature is below +60*F then the grid heaters will still fire. 

 

You are correct on the 3/6 CYL run mode that is strictly only ECT and IAT control.

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Buy a brand other than Nippon Denso or Napa, Bosch, Nations etc.  The Nippons an clones often have too much AC out of the box.

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5 hours ago, bigfish95971 said:

Buy a brand other than Nippon Denso or Napa, Bosch, Nations etc.  The Nippons an clones often have too much AC out of the box.

 Sorry I’m a little confused. Your saying to stay away from Nippon Denso AND all those other brands or those other brands are okay to use?? I didn’t think there was any alternative besides the standard denso/clones..  

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I'm looking at it from another angle of attempting to find a solution to the issue instant of limiting parts or pushing towards expensive solutions. I can provide that the diode failure is caused by excessive high amp draw on the system at idle. Like the majority of diode failure is caused by people in the cold country firing up and leaving the truck idle to warm up. This places large load again the alternator and the diodes get overheated from attempting to hold the grid heater at an idle. I'm doing some testing right now to see about resolving this issue.

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I'm pointing at a sticky post above :thumb1::thumb1: Thank you.

 

Beside an alternator with double capacity, what other recommendations do you have to help upgrade the system?

 

Are you speaking about what is called a true triple K alternator? Is that the one?

Edited by JAG1
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@W-T I've converted your post into an article to keep for all to see thank you for the wonderful explanation of the alternator function.

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No, I am saying that the Bosch and Nations are better options than Nippon or Napa.  I once tested several Nippon's and Napa's and they were all over .03v in the box, and one was even not charging at all tool.  The Bosch was the only one that tested around .02v ac.  Never messed with Nations, but others have said they  like them.

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@W-T Wow!! Thanks a lot for that. Have you been able to find an alternator that meets the criteria you spoke of?

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I bought the Bosch, but there are others.  The thing to is test for AC before purchase or immediately upon installation.

Edited by bigfish95971

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I’ve been trying to search without luck but is a Bosch alternator actually a different design than the denso unit? I imagine most commonly reman units are denso? What’s the difference between the two?

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12 minutes ago, skyhigh4by said:

What’s the difference between the two?

 

Denso is simple to rebuild with basic hand tools where the Bosch has all the diodes soldered in place. 

 

Denso diode pack. Easy bolt on part. Brushes and everything else is easy to replace. 

diodes.JPG.75934d4fd5a872402af434fba5540

 

 

6 hours ago, W-T said:

ALSO...guys I lurk around out here...I've seen photos you have all taken "under the hood" of your beloved vehicles...gosh golly!!! The appearance of the battery terminals and cable connectors...it is pretty sad. You can't transfer billions and billions of electrons (with NO heat) through the scum I have viewed. 

 

 

Something like this?

I posted a bad battery here before but this ones pretty nasty too

  • Haha 1

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