From: xenolith@optusnet.com.au   
      
   On 10/5/2023 3:05 am, 😎 Mighty Wannabe ✅ wrote:   
   > On 5/9/2023 10:39 AM, Xeno wrote:   
   >> On 9/5/2023 11:34 pm, 😎 Mighty Wannabe ✅ wrote:   
   >>> On 5/8/2023 11:58 PM, Ivan Vegvary wrote:   
   >>>> 1948 Pontiac, 12V battery, one wire alternator (was working when   
   >>>> parked 12 years ago).   
   >>>> No amperage reading even at 2000 rpm.  Battery voltage 12.6V.   
   >>>> Battery voltage with car running 13.8V, however amp meter only reads   
   >>>> 0 or negative with headlights on.  Placed an after market ammeter   
   >>>> between the alternator and the battery.  Same reading as ammeter in   
   >>>> the dash.   
   >>>> How could this be?  Alternator supplies voltage but no current.   
   >>>> After idle for 12 years maybe residual magnetism is gone. Needs to   
   >>>> be excited.  Can't find a YouTube that shows me which terminals to zap.   
   >>>> All help is appreciated.  I can certainly buy a new unit, but   
   >>>> possibly have other problems.   
   >>>>   
   >>>> Thank you   
   >>>   
   >>> If you get 13.8V when the car is running, that means the alternator   
   >>> is providing output.   
   >>>   
   >>> The alternator output is AC. You need to use AC ammeter to measure   
   >>> the AC current output from the alternator.   
   >>>   
   >> Correction, the alternator output is DC. The 6 internal power diodes   
   >> provide the necessary rectification. The 3 exciter diodes are meant to   
   >> excite the field coils and set the generation process into gear.   
   >>   
   >   
   >   
   > Are you sure that's true for 1948 Pontiac?   
   >   
   > Maybe that alternator had been modified to use external rectifiers and   
   > regulator.   
   >   
   Then it wouldn't be a single wire alternator, would it? Think about that   
   for a moment. Alternators are, typically, 3 phase. That means 3 +ve   
   power diodes, 3 -ve power diodes and 3 exciter diodes. If there is only   
   one output wire, then all *rectification* and control has to be on-board.   
      
   --   
   Xeno   
      
      
   Nothing astonishes Noddy so much as common sense and plain dealing.   
          (with apologies to Ralph Waldo Emerson)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)