Single wire 100 Amp Alternator

Discussion in 'The Projects Forum' started by Duane P Wetick, Oct 28, 2013.

  1. Duane P Wetick

    Thread Starter Active Member

    Apr 23, 2009
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    This 100 Amp Alternator replaces a 3-wire 55 amp unit on a boat engine and I am concerned about the field (flashing) requirement. The Alternator output stud is connected to an Isolator Diode Anode, Cathode to the +12 VDC Battery post.
    - terminal to engine block. Do I need to add a separate 12VDC line to the Alternator output stud? There are no other connections on this Alternator...and no instructions either. I may be running my engine on battery power alone with the Alternator idling and not charging the battery. Comments, anyone?

    Cheers, DPW [Everything has limitations...and I hate limitations.]
     
  2. cornishlad

    Member

    Jul 31, 2013
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    what is the purpose of the diode ? Is there a cranking battery connected directly to the alternator ?
     
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
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  4. Duane P Wetick

    Thread Starter Active Member

    Apr 23, 2009
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    Distributor is RareElectrical Devices, a large supplier of electrical devices...
    No electrical diagram is available...but I'll try again...Alternator has only one terminal, besides case lug.
    I am most concerned about the field flash...doesn't the field have to be flashed momentarily before the Alternator starts sourcing power?...Alternator delivering 14.6 VDC to Isolator diode...14.0 VDC on Battery + terminal at the dock.
    Batteries appear to be charging...but, next day, traveled 7 miles with boat, shutdown engine...tried to re-start after several minutes and engine refused to crank...both batteries were flat! Came home on auxillary engine. No idea what caused this, but apparently, Alternator was not delivering power...I'm concerned about field flashing now.

    Cheers, DPW [Everything has limitations...and I hate limitations.]
     
  5. bwilliams60

    Active Member

    Nov 18, 2012
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    The 1 wire alternator has been around for years and is based on a self exciting principle. In a regular two or three wire alternator, there is an input to the voltage regulator from your ignition via the "idiot" light which turns on the voltage regulator. As you may or may not know, the voltage regulator is in charge of turning the rotor(field) on and off very rapidly(400 times per second) to control voltage. Effectively what you are doing is creating an electromagnet and turning it on and off very quickly. By doing so, over the course of time, the iron core will retain some "residual magnetism". In a single wire unit, it is imperative to have this residual magnetism to turn on a specially designed voltage regulator. If for some reason, you lose this magnetism, you must reflash the unit to get it to turn on. If you are indeed getting 14.0 volts, then the alternator is turning on and you may be having other issues. It almost sounds like you may have flat batteries but without more information, it is hard to make that conclusion. First, lets get the make, model and rated output of this alternator and if you have a picture of the alternator, even better. Next, lets get the working voltage of this when it is running and we will go from there.
    Note: I had an auto electric business for a number of years and have built many of these units.
    Question: You said this is marine. Is this a marine alternator or automotive alternator put on a boat?
     
  6. Duane P Wetick

    Thread Starter Active Member

    Apr 23, 2009
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    I think I've got a handle on the problem now...Alternator Mfgr. says to connect the output directly to the battery + terminal. I am going thru an isolator diode first and that is not allowing the field to flash. ie;the isolator diodes prevent Battery No. 1 from discharging into the Battery No. 2, but allow the Alternator to charge both. The solution may be to either remove the isolator (unlikely) or add a separate +12VDC line from the circuit breaker upstream(battery) side back to the Alternator + output stud.
    This a marine rated Alternator...

    Cheers, DPW [ Everything has limitations...and I hate limitations.]
     
  7. bwilliams60

    Active Member

    Nov 18, 2012
    722
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    I'm not sure you or your supplier quite understand this alternator. If it has been built right using the right parts, the residual magnetism in the rotor should be enough to start producing current right away(induction). I know what a battery isolator does and I also know that there are a lot of issues with battery isolators. Not sure where you are going to jump your output post to, but I suspect disaster lies ahead. Have at it but not a recommendation you seen here. Good luck. I'm out.
     
  8. JoeFromOzarks

    Active Member

    Apr 14, 2010
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    +1 There is more: http://forum.allaboutcircuits.com/showthread.php?t=90462


    Wouldn't that configuration effectively/electrically bypass the isolator?



    :) joe
     
  9. JoeFromOzarks

    Active Member

    Apr 14, 2010
    95
    27
    @Duane P Wetick

    What model/manuf is the isolator you're using?


    Have a look at this, for example. http://www.yandina.com/c160Info.htm

    This unit works with 1-wire alternators. This is just an example, I have no experience with this specific offering.

    :) joe
     
    Last edited: Oct 29, 2013
  10. Duane P Wetick

    Thread Starter Active Member

    Apr 23, 2009
    408
    19
    This unit is no cheap date either and without a detailed explanation of how it works, I'm reluctant to put it on a boat. I insist that everything on a boat related to propulsion be completely understood, or I will not install it.

    Cheers, DPW [Everything has limitations...and I hate limitations.]
     
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