From: @.   
      
   On 5/11/2023 8:47 PM, Snag wrote:   
   > On 5/10/2023 7:33 PM, 😎 Mighty Wannabe ✅ wrote:   
   >> 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.   
   >>   
   >>   
   >   
   >   It must be quite difficult to blow smoke up somebody's ass with your   
   > head so far up your own .   
      
      
   Do you have a better explanation for a DC ammeter not registering any   
   amperage at the alternator other than the alternator is outputting AC?   
      
   The OP should try using AC ammeter to confirm that the alternator had   
   been rewired to output AC, and external germanium bridge rectifier is used.   
      
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