From: xenolith@optusnet.com.au   
      
   On 12/5/2023 1:37 pm, 😎 Mighty Wannabe ✅ wrote:   
   > 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.   
      
   Ah, a thought experiment! That explains why you don't get it.   
      
   --   
   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)