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Hot Rods 1 wire alternator help

Discussion in 'The Hokey Ass Message Board' started by john mullen, Feb 12, 2015.

  1. I have 2 hot rods that have 1 wire alternators on them. on both cars when the car is started up the belt to the alt will slip and squeal no matter how much I tighten the belts One is 100 amp and the belt will stop squealing after about 60 seconds it doesn't do it if the battery is at 100 present charge only when it is at a point that it starts to charge is when it squeals . the other is a 150 amp alt and it squeals all the time and I can't get it to stop. I can live with the 100 amp but the 150 amp seems to be very hard to turn when hooked up and charging ' I can take the 8 gauge wire off the back of the alt and it doesn't slip at all . the belt is new and I have it so tight I am afraid it will eat up the alt bearings and it still slips.

    Ok now for the QUESTION .... anyone having this problem with the 150 amp or the 100 amp 1 wire alternators ???
  2. Yeah but changing the pulleys to a tandem [2] belt setup will fix it. So will a serpentine belt setup but that wouldn't be traditional.
    I had this problem at work with a ford truck we installed an inverter and 2, 150 amp alternators, each with it's own V-belt...had to double up on belts for both alternators.
  3. V-belt drive? Those large alternators are really designed to use serpentine belts with plenty of 'belt wrap' and more surface area on the pulley. It takes over 2.6 HP to produce full power on that big one...

    Yep, run two belts.
  4. Fabber McGee
    Joined: Nov 22, 2013
    Posts: 1,042

    Fabber McGee

    Why in the world do you need such big alternators? Is your hot rod a motorhome, or a school bus? Sell the big ones, put a 50 amp on them instead and forget it. Smaller, lighter, cleaner with single belts and less expensive.

  5. I was thinking the 2 pully2 belt was what needs to be done but I do not have the room on the 150 amp set up... how about a bigger diameter pulley? the one on it now is approximately 2.5 " in diameter .I saw on in the summit catalog for racing app..
  6. jseery
    Joined: Sep 4, 2013
    Posts: 743

    from Wichita KS

    I was getting ready to ask the same question, why such big alternators? Their just eating up horsepower and causing problems unless you really need them for something. Some big ass over sized stereo? Hot Rods should run on 35 to 50 amp alternators easily. Tightening up the belts is going to cause no end of problems. If you must have the monsters then then you are going to have to add a drive that can handle them.
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,210


    I don't run one-wire alternators, but I do run a 100A one in my Falcon (AC, EFI, huge stereo). No issues.
  8. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 27,741

    Jalopy Joker

    post pics of motor/belt set up. even if both pulleys V-belt style there may be a difference in the width of them - need to match. running a racing pulley? what does removing the primary wire have to do with belt slipping? pulleys painted or polished - can add to slip factor.
  9. Been running 1 wires for years without any of the mentioned problems..... You don't need two belts or anything else..... it's the same as the lowely 45 amper back in the 60's..... Correct pulley alignment,and correct pulleys/belts are the problems..........
    running a 1 wire and the alt is flipped backwards= body is in front of the engine! 130 amp SI,and have never experienced the mentioned problem(s).
    Just a bigger (amps) alt, can keep up( read into this),draw from the drain from your electrical system.....So much more to the story with alt's,but, sort some things out first.
    And- reading the above above post's.... Just say you run an electric fan,possibly an electric fuel pump,with headlights on,possibly a heater..... maybe in the rain..... ummmmm- how many amps does that pull?
    You'll be fine with what you have,just have to sort some things out... If you have an alt/gen shop around,speak to them. By-pass the chain stores for your own sake.

    Attached Files:

    26 roadster likes this.
  10. A bigger diameter pulley may help by giving more surface area for belt contact, but it will also slow the alternator; you may not have enough RPM to get needed output at slow engine speeds. Unless you need that monster, swap it for a lower-output version.
  11. gas & guns
    Joined: Feb 6, 2014
    Posts: 370

    gas & guns

    V belt pulleys can also wear out so they re not making full contact with the new belts.
  12. A pic of your belt drive, I just run an a 1 wire 140 amp, and works fine. You need enough of the belt wraped around the pully.
  13. I added all the amperage needed for my car with every thing on at one time... head lights, wipers, heater, radio, electric fan, electric fuel pump, dash lights, map light, and I came up with 90 amps used.
    my alternator size data in the original post was incorrect. they are 100 amp and 80 amp units..
  14. jseery
    Joined: Sep 4, 2013
    Posts: 743

    from Wichita KS

    Something doesn't sound right, how can the amp total be that high. My kids drive Fox body mustangs with stereos in them and electric everything on 50 amp alternators. Some headlights can be 35 amps, but don't need to! Other than the fan the rest of that should be little to nothing amp wise, unless it has a big stereo amplifier. Well, the 100 and 80 are better sounding. IMHO it is still oversized, you just don't run all of that stuff at once. But there may be other problems such as why is the battery pulling such a charge on the alternator. Something does seem strange. My biggest concern would be over tightening the belts. Here's a suggestion, LED lights!

    Just looked up some fans, 5 to 9 amps, fuel pumps 5 to 10
    Just ran everything you listed through an online automotive amperage calculator, came up with 38 amps. So I'm guessing you may have over estimated your requirements.
    Last edited: Feb 12, 2015
  15. Fabber McGee
    Joined: Nov 22, 2013
    Posts: 1,042

    Fabber McGee

    Fullblast may be on the right track here. You need as much belt contact as possible. More is better. If you can get up close to 180 degrees of contact, the belt will actually be wrapping into the groove and sort of self tightening. 90 degrees or less and you don't have much chance of stopping the squeal. If there is no other choice, you could run an idler on the back of the belt and on the slack side of the pulley to get more wrap. You may even get past 180 degrees that way. Let's see some photos.
  16. If you arrived at that number by adding up your fuses, the actual load is less. Fuses are sized (or should be) at 125% of the actual load. So actual load would be 80% of your total fuse values. If that's 90, the actual load is 72 amps or less. Now, you should also 'derate' the alternator. They don't like being operated at 100% either; again, 80% is the preferred number your looking for. Your 100 amp unit is big enough, as would be a 90 amp unit, anything smaller may be too small.
  17. jseery
    Joined: Sep 4, 2013
    Posts: 743

    from Wichita KS

    As a side note I understand crazy amperage in car. One of my kids had a Blazer with stereo gear in it (competitive type). It had two 140 amp alternators and six batteries in that stupid thing.
  18. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 685

    Jack E/NJ
    from NJ

    >>> I can take the 8 gauge wire off the back of the alt and it doesn't slip at all .>>>

    Doesn't matter how many amps the alternator can allegedly put out. You either got a big drain (short or bad battery) or bad internal regulator. What does the voltmeter or ammeter read with lights off while running? What is battery voltage not running?

    Jack E/NJ
  19. Yeah jseery I can relate to the stereo gear, I did a nice build for a guy who latter installed some very heavy amplifiers and set the truck on fire.. Burnt it to the ground . anyway thanks for your input...
  20. fordflambe
    Joined: Apr 9, 2007
    Posts: 556


    ditto some of the comments above regarding belts and pulleys.........the v-belt is supposed to ride on the sides of the v inside the pulley, and not on the bottom of the v. Older pulleys will actually show a groove on the sides where the belt has actually worn away the metal..........inspect your pulley and make sure your belt is not bottoming out on the pulley.
  21. the battery is new with a full charge showing 12.6 volts on the tester. No draw when I remove or install the battery cables ( no visible discharge or spark )
    I'm thinking when I start the engine all that the alt should be doing is replenishing the voltage used at start up and the voltage being used by the ignition. .....Please comment some more on how the internal regulator works....
  22. Thanks fordflambe, I will check that out ...
  23. jseery
    Joined: Sep 4, 2013
    Posts: 743

    from Wichita KS

    Where did the alternators come from, any chance there not setup properly? Something is causing the alternators to be loaded heavy when their connected to the battery. They shouldn't have that much draw on them.
  24. Belt squeal right after starting isn't uncommon; the alternator will go to full charge to quickly replace the large draw. But if it keep up more than a few minutes, then you probably do have a problem with either the alternator or the drive system.
  25. I think of all the GM cars I drove for eons with a 37A or 63A alternators if it had AC.
  26. I purchased the alt at the Charlotte auto fair from a vendor. not cheep but not expensive ether. I'm sure it is installed properly. Can I check the output of the alt with nothing hooked to the 12v out post but a tester of some sort
  27. BobMcD
    Joined: Jan 25, 2013
    Posts: 322


    I've had issues with some belts that stretch like a rubber band and would squeal no matter how much you tightened them. I now use Gates belts, from Napa
    and have not had anymore issues with squealing.
  28. Ditto on the gates belts, that's what I have
  29. 55Brodie
    Joined: Dec 15, 2008
    Posts: 746


    Backside idlers are not recommended on v-belts. You might want to try a belt having notched construction (sometimes called cogged) on the v side. This allows the belt to conform to the smaller diameter sheaves and provide greater contact. Increasing center distances by moving the alternater farther away from the other sheaves also increases the arc of contact.
  30. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    if the sheaves had any rust on them and you put the belt on without removing it first it will embed itself into the face of the belt and cause it to slip ( ruining the belt ) , also a one wire shouldn't fire up immediately after cranking it should kick in about 800-900 rpm and then shut off at 450 rpms , sounds like they put a standard or cheap regulator in it and are looping it to turn off/ on ( you can check this by turning the key on/motor off and placing a screw driver near the rear bearing housing , if the screwdriver is pulled to it the unit is turning on with the key , not by the self excitation voltage . and the alternator is going to kick in hard after starting as it has to charge the battery back up from the high draw of cranking .

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