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??

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

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.  

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?? 

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. 

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.

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.

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.

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.

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.

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.

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.

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..  

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.

Mike is correct...the large current load on these 3 phase hairpin stators in conditions where all the available current is delivered does tax the design of the factory alternators. The diode's are all created on a single silicon substrate to assure uniform junction characteristics. This method allows for the PIV (peak inverse voltage) to closely match across all six diodes in a "three phase" rectified bridge. The old school would be to use individual large stud mounted diodes however; they would have to be curve traced to create a matched set of six diodes with close PIV and forward current avalanche voltage drops. All silicon diode junctions have a .6 volt drop turn-on when forward biased or conduction. Variations of these characteristics cause a dirty wave-form of the desired sinusoidal wave appearance. Hence; we have "ripple" witch is what Mike has explained so many times and why we must avoid this situation. 

 

Our trucks arrived with a "bare minimum" alternator design to get the vehicles off the sales lot. The grid heater configuration along with head lights and a fan blower for heat or defrost on early cold mornings takes the demand for these wimpy alternators to their design limits. Once we begin to "pound or beat" these diodes into forward and reverse current conduction we begin to see changes in the silicon junctions. It is cumulative and in time between hot summer and cold winter conditions our diode bridges become "leaky" and the "ripple" (AC component) becomes excessive and certain electric system devices begin to balk or react strangely with the imposed "ripple" floating on the DC(direct current) rail.

 

Excellent mil-spec electronic devices or space-bound instruments MUST HAVE bullet proof power supplies. PURE DC hard-core power supplies are normal components and can be built without much effort today. Our alternators and dual batteries ARE the DC supplies for our trucks. The error is budget on Daimler/Chrysler's decision to put these 135 amp alternators into the Cummins platform. 

 

The standard rule of thumb for all electronic design regarding power supplies is, "If you have a demand of 100 amps maximum in a given system, you build a supply with 50% more headroom minimum. Now, take conditions into consideration...heat, cold and perhaps a poor matched battery in a dual battery (paralleled batteries) storage supply and the occasional "starter" operation (the Cummins starter is INSANE on current demand!) and WE have a real MONSTER to feed!

 

Boys and Girls...if you want bullet-proof DC, double the available current at idle. Yes...this is correct...go with a 6 phase (twelve diode pack) and a hand-wound "square wire" hairpin-stator. The six-phase stator and companion rotor  will cut the ripple to near zero in conjunction  with proper storage capacity (really good paralleled batteries) you will have the power supply for your Cummins. The "square" wire wind is best for current demand when an "AC field wave-form" is cutting the coil to impose current into the inductive system. It is the cutting edge in design for transformers with high efficiency and LESS HEAT. Heat is "loss" and also destroys the surrounding aspects of the generating device.

 

BTW...not even Nations builds to these specifications....they buy their upper-end higher current devices from a source in Riverside California.

 

Just for grins... 1 Amp...what is this? Electronics 101:

 

Current flow is "electrons" ( remember 5th grade science?) the Atom is composed of three elements the Proton, Neutron and the little Electron flying around the other two elements like an orbiting satellite. It is the "electron" we are interested in when it comes to DC (direct current) when we refer to "current flow" in a circuit.

 

SO...the question is? When we measure "current flow"  the term Amps is used....how many "electrons" flow through a piece of wire at a given point in "one second" ???

 

One Amp is (physics term "Coulomb" ) equals 1x10 to the eighteenth power....hence; when you start your mighty Cummins you are transferring 1x10x18 x 600 electrons in order to spin the Beast into run condition ! Take a look at the size of this number ! This is why you need "FAT" wire to allow all those little (minions) electrons to race at the speed of light through the wire to the given load. 

 

As you can see...current flow is from "negative" to "positive" in our world. The battery has a "positive" terminal and it is "sucking" to become satisfied. It attracts ("sucks") electrons off the frame-rail of your truck "as current flow" in order to spin the armature of the starter motor.

 

SO..."negative" (electrons) flow towards the "positive" (hole or sucking-action)....seems we have an "upside down" world !!!!

 

Now this leads us to another interesting Physics observation...you see...lights Do Not Give Off Light ! They suck "dark" and you will notice when a light bulb "burns out" and no longer provides luminescence....we say "it is burned out" however; we now know that is not true!.... IT IS FULL of Dark and we need a new bulb ...Look at the bulb...it's "dark".

 

Sorry...had to share this funny tid-bit...none the less...our Cummins platforms were not produced with Mil-Spec in mind. Sorry, our ECM and PCM's must be provided "clean" stable DC in order to function correctly. The design guys never considered 6 millivolts  of "ripple" to be critical for converter "lock and unlock" syndrome and yet we see the result and unwanted operational characteristics. 

 

I build killer DC power supplies for various electronic devices...you need a shop oscilloscope to even see the minor "AC ripple" and as for regulation, from zero to 100 Amps at 14.8 volts there is NO DC drop in voltage. It is like taking and engine from "zero" to "red line" in a heart-beat and you don't even see a fraction of a voltage drop...this is called a "Stiff DC Regulated Supply".

 

Build your DC Supply...the Cummins platform is a Nobel Beast....feed it a good stiff DC diet with NO sag and Zero ripple and all will be well.

 

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. 

 

Again...No worries...we are all in this together... I share this respectfully as intellectual content with just a touch of humor  

 

Cheers

 

 

  

         

I'm pointing at a sticky post above  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 January 15, 20187 yr by JAG1

So with all that said. Where do we find such an alternator that is up to the task

@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.

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.

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

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

Edited January 15, 20187 yr by bigfish95971