From: @.   
      
   On 5/11/2023 11:11 PM, Snag wrote:   
   > On 5/11/2023 9:49 PM, 😎 Mighty Wannabe ✅ wrote:   
   >> 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.   
   >>   
   >>   
   >>   
   >   
   >   The simplest explanation is that the slip ring brush isn't making   
   > the circuit to excite the rotor windings . That alone would explain   
   > the voltage reading 12.8V while running - and slightly higher when   
   > stopped and there is no current draw for stuff like ignition and   
   > instruments .   
   >   The next simplest would be that the internal regulator is bad , also   
   > resulting in a lack of charging .   
      
   Your explanation cannot explain the phenomena the OP had observed:   
      
   "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."   
      
   Apparently the alternator is charging the battery. My explanation,   
   albeit convoluted, can explain exactly how it is possible. The previous   
   owner didn't want to buy a new alternator and used this convoluted way   
   to get by. The previous owner wired the alternator to output AC, and   
   used external germanium bridge rectifier to get DC. My thought   
   experiment can explain all the observed phenomena in this case.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)