From: @.   
      
   On 5/10/2023 9:39 AM, 😎 Mighty Wannabe ✅ wrote:   
   > On 5/10/2023 12:55 AM, Xeno wrote:   
   >> 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.   
   >>   
   >   
   > If the alternator really has DC output, then the car's [DC] ammeter   
   > and external [DC] ammeter should register DC current.   
   >   
   > I believe somehow the alternator burnt the internal diodes, and the   
   > owner rewired it as single phase [AC] output and used external [bridge   
   > rectifier] after the car's dashboard [DC] ammeter. That means the   
   > dashboard [DC] ammeter has not been working properly ever since   
   > [because it was AC coming from the alternator]. A germanium [bridge   
   > rectifier] was used so some reverse current is flowing back into the   
   > alternator when the engine is not running but the key is on auxiliary.   
   > That's when and why the dashboard ammeter registers negative.   
   >   
      
      
   I've some made minor corrections in square brackets [    ] above to   
   clarify my points.   
      
   I think I have the correct line of thinking.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)