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Technical Alternator Question

Discussion in 'The Hokey Ass Message Board' started by Dooley, Sep 13, 2017.

  1. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    I have a large amp at idle GM alternator that is chrome have 2 issues with the internal regulator.
    Alternator was putting out 17.5 volts...not good, this was checked by my voltmeter in the car and a meter on the post on the back of the alt while running. I have a regular non chrome GM alt that I put back on and had no issues. I bought a replacement regulator and changed it. Put the chrome one back in and worded fin until it started only putting out 12 volts per my voltmeter and verified at the alt with a handheld meter.
    Pulled the trusty gm alt and reinstalled it. no problems

    Her is my questions, since I have no issue with the non chrome regular GM Alt I assume that my wiring is correct.

    what could cause the failure in the chrome high amp alt?
    Chrome attracting too much heat? engine bay does get hot
    Or is the high amp output that may not be needed causing an issue?

    I bought it because I had wired my electric fan outside the charging circuit with the ammeter and had an issue losing my lights at night at idle with the fan on, that was corrected when I changed to a voltmeter.

    Thanks
     
  2. Blues4U
    Joined: Oct 1, 2015
    Posts: 1,550

    Blues4U
    Member
    from So Cal

    Don't think the chrome has anything to do with it. BTW, chrome would reject heat, not attract it, right?
     
    carolinakid and INVISIBLEKID like this.
  3. 325w
    Joined: Feb 18, 2008
    Posts: 4,716

    325w
    ALLIANCE MEMBER
    from texas

    Chrome might hold heat in and not disburse thru the aluminum. Had an alternator ceramic coated and it ate diodes. Tech guy thought it was from the ceramic holding heat.
     
  4. jimmy six
    Joined: Mar 21, 2006
    Posts: 1,932

    jimmy six
    Member

    Chrome alternator?
     
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  5. tfeverfred
    Joined: Nov 11, 2006
    Posts: 14,766

    tfeverfred
    Member

    Maybe it's bad. It happens. How sure are you it has an internal regulator?
     
  6. e1956v
    Joined: Sep 29, 2009
    Posts: 1,061

    e1956v
    Alliance Vendor

    What do you do when you bake a potato? Wrap it in foil.
    Chrome does trap the heat, we sell chrome alternators but I don't warranty them.
    If the inside also has plating the ground may not be good under the regulator, take it back apart and file the area where the regulator grounds. It's the outer most post next to the plug. Give that a try.

    Sent from my SAMSUNG-SM-G890A using The H.A.M.B. mobile app
     
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  7. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 4,900

    scrap metal 48
    Member

    I think the problem is the electric fan.. Put a mechanical fan back on and I bet the problem goes away....
     
  8. Budget36
    Joined: Nov 29, 2014
    Posts: 1,180

    Budget36
    Member

    You replaced the internal regulator?

    Interesting.

    The setup, should give you around 14 volts at idle, as checked at the battery, most prefer 14.2 volts, regardless of what you want to run, that is what you should be running....assuming a charged/god battery.
     
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  9. Blues4U
    Joined: Oct 1, 2015
    Posts: 1,550

    Blues4U
    Member
    from So Cal

    Yeah, but when you do that you put the shiny side IN, and the dull side OUT (or you should).

    A chromed surface will not release heat as well as a black surface, but it does not attract heat. So a chromed alternator theoretically COULD hold onto more self generated heat, but with all the chromed alternators out there, I don't think it is a common problem. Maybe if the load on the system approached the capacity of the alternator and it was always working near max output. Otherwise, I think there's something else going on with this guys machine besides the chrome.
     
  10. Truck64
    Joined: Oct 18, 2015
    Posts: 1,258

    Truck64
    Member
    from Here

    Like hell I do. Poke holes in it, slather it in butter, or bacon grease. Foil will cause it to "steam" cook, don't want that.
     
  11. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    it is chrome
    it was fine, then read 17.4. I changed the regulator and after it read 14 again...then a few weeks later it went down to 12 volts. The non chrome alt was and is used as a replacement and is working fine and has been
     
    Last edited: Sep 14, 2017
    simpsonrl likes this.
  12. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    i did read elsewhere that if using a high amp alt without any real draw could cause issues, other than the fan i have lights and an electric fuel pump ad the fan only runs on and off when needed.
     
  13. manyolcars
    Joined: Mar 30, 2001
    Posts: 6,758

    manyolcars

    no one has suggested that he see if the brushes are worn out???
     
  14. I would make sure all the grounds are good first. Have you had the chrome one checked out by an auto-electric shop? I had the 63A one done over in my car, was great for a year then the volts started spiking all over the place. Took it back and they put a new regulator in it and that fixed it. In cases like yours a pro can narrow it down fast.
     
  15. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    its only a year or so old....could be. Its a power master maybe I should have used a different regulator when I changed it?
     
  16. e1956v
    Joined: Sep 29, 2009
    Posts: 1,061

    e1956v
    Alliance Vendor

    If you have a local rebuild shop they can test the regulators. Powermaster uses standard Delco parts nothing special.
    I could test the regulators for free but It still isn't worth the shipping.
     
  17. porknbeaner
    Joined: Sep 12, 2003
    Posts: 38,561

    porknbeaner
    Member

    This is solid logic here. A chrome part does not dissipate heat as a non chrome piece, but if it is shiny it would reflect heat not absorb it.

    What makes an alternator put out more amps is the stator primarily. But you need the proper diode plate and regulator. I built a 110 amp alternator for an old project that used lots of electricity from a stock 65 amp 1 wire back in the '90s. I still own it and it still works well. I did loose a regulator in Texas in about '02 and picked up a regulator at the Zone for a stock 1 wire and repaired it to get me home. It was showing improper voltage before I got back to KC so I called the catalog speed shop where I got the parts originally to soup it up and they sent me the proper regulator. What they told me was that the higher amperage was taking the stock regulator out. I don't know how true that statement is but it makes sense and I have not replaced a regulator in it since. Lots of miles on that alternator, its due for bushings now but it still does what it is supposed to.
     
  18. e1956v
    Joined: Sep 29, 2009
    Posts: 1,061

    e1956v
    Alliance Vendor

    My point was that it traps heat from the alternator charging and does not dissipate it like natural aluminum does.
    We have more chrome alternators in for rebuild issues than natural case alternators. They are pretty but I stand by my foil wrapped analogy.
     
  19. I really doubt temperature is your problem. If your stock alternator isn't frying, neither should your chrome one. There are three modes of heat transfer; 1) radiant heat transfer is heat being transferred from a hot body to a cold one by radiation. This is the heat you feel standing in front of a campfire or standing out in direct sunshine on a 115F Bakersfield summer day, 2) conductive heat transfer is heat transmitted by a hot body touching a colder one. This is the heat you feel when you grab your hot exhaust headers, finally 3) convective heat transfer which is heat being transferred by a fluid of a different temperature flowing over a body. This is the heat transfer you feel on those rare times when the A/C is working in your hot rod or from the heater blowing warm air at you.

    Those are external sources of heating. The only other thing that can be heating your alternator is internal heat generated during electrical generation but that is proportional to the power the unit is making and the stock alternator should be generating the same power as the chrome one so you should be able to eliminate that cause of overheating.

    Getting back to heat transfer problems, you should be able to eliminate conductive heat transfer from an external source since an alternator is not in enough contact with any other engine part to be significant. Also eliminate heat gain from radiant sources since the shiny chrome surface has very low radiation coefficient and doesn't absorb or re-radiate heat much at all. Even though the chrome surface doesn't radiate internal heat very well, compounded by the fact that chrome has less than half the thermal conductivity of aluminum so internal heat conduction through the case is inhibited very slightly, neither of these mechanisms are significant in an alternator. Copper which may be a layer of plating in the chrome process is twice as thermally conductive as aluminum so it isn't a suspect.

    That leaves the 800# gorilla in the room, convective heat transfer. Remember that all alternators are equipped with copious vents in the case and with a really efficient and relatively large cooling fan. ANY heat generated internally and/or absorbed externally is extracted by the air convection inside and outside the unit. The only two things that overcome this thermal protection is if the air being blown over the alternator is too hot to extract the necessary amount of heat generated by the unit or the unit is generating so much heat that even the relatively cool air stream can't extract it fast enough.

    In view of the above I am pretty sure your problems are electronic. One or two dead diodes in a set are really hard to detect and cause really weird problems. Better to have the whole set of diodes blow. In my experience 99.99999% of my electrical problems it seems have been grounding problems but I don't know how that would contribute to the problem you describe.

    GM alternator rebuild kits are (used to be?) really cheap, I would try a full set of replacement diodes and regulator.​
     
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  20. Alaska Jim
    Joined: Dec 1, 2012
    Posts: 130

    Alaska Jim
    Member

    replacement voltage regulators for the internal regulated alternators are not as good as they used to be. you may have just got a bad one. I used to rebuild these alternators all the time back in the '70's through the '90's. I always replaced the diode trio, and the regulator at the same time . called it insurance , when doing it for a living. never had one come back. I think you just got a junk off shore made part.
     
  21. Yes, rebuild kits are available for less than $20 with diodes, VR, new bearing, & brushes. I would dump in all new parts and that should do it.
     
  22. Alaska Jim
    Joined: Dec 1, 2012
    Posts: 130

    Alaska Jim
    Member

    one other thing, if you decide to rebuild it , test the rectifier bridge, these rarely go bad ,but if you have it apart, you should test it. .
     
  23. Mr48chev
    Joined: Dec 28, 2007
    Posts: 21,196

    Mr48chev
    ALLIANCE MEMBER

    I agree with Alaska Jim right there. Pull the thing apart an start checking the pieces to see what you have. It isn't rocket science to check the diode bridge, tri diode, rotor or stator. Most parts houses have regulator testers.
    Did you coat the hell out of the regulator with dialectic grease? They don't last long if you don't.
    I used to get rebuild kits for my big frame Cad alternators from Napa an I imagine they have kits for the smaller frames.
    I'm not well versed in how chrome effects heat transfer but guys have run chrome alternators for the past 50 years or so and most don't have any more problems than guys who don't have a chromed one. Good thing is that if they do crap out you can do just as you did and pull a regular one off the shelf and go again.
    I'd check it out, buy a quality regulator and slather the dialectic grease on the back of it put it back together and go again.
     
  24. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    no grease..
    thanks for the tips, some good advice that I plan on following
     
  25. I'm guessing you actually meant thermal paste, not dialectic grease like you'd use in spark plug boots. Also check that the bearings aren't dry while you've got it apart. If you can feel any roughness when turning the bearings by hand they should be replaced. A worn or dry bearing can produce plenty of heat.
     
  26. Dooley
    Joined: May 29, 2002
    Posts: 2,225

    Dooley
    Member
    from Buffalo NY

    I'll check the bearing when I get it apart, ordered a new kit with diodes this am, I'd like to know about the grease or paste part...
     

  27. https://en.wikipedia.org/wiki/Thermal_grease

    Thermal paste (or grease) promotes thermal conductivity between surfaces. Some of the main usages are for the processors on computer motherboards, and the mounting surface of ignition modules in electronic ignition systems.

    Dialectic grease is a high-silicone lube usually used in electrical connectors and spark plug boots to seal out moisture, prevent corrosion and allow for easier disassembly. It is well suited for the job since the silicone base lube will not attack or degrade plastic or rubber as petroleum based greases can.
     
  28. porknbeaner
    Joined: Sep 12, 2003
    Posts: 38,561

    porknbeaner
    Member

    I think it is a good analogy it at least gives the reader something to ponder which is what an analogy is for, right?

    Here is the deal, chrome parts on a motor have always caused problems that painted or bare parts have not. There is a reason that OEM parts are not plated, I admit that part of that is cost, but the other part is reliability. In any Engine bay heat is your enemy.
     

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