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|    rec.autos.tech    |    Technical aspects of automobiles, et. al    |    117,728 messages    |
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|    Message 117,342 of 117,728    |
|    =?UTF-8?B?8J+YjiBNaWdodHkgV2FubmFiZ to Xeno    |
|    Re: One wire alternator question    |
|    13 May 23 07:18:57    |
      From: @.              On 5/13/2023 7:05 AM, Xeno wrote:       > On 13/5/2023 8:39 pm, 😎 Mighty Wannabe ✅ wrote:       >> On 5/13/2023 5:33 AM, Xeno wrote:       >>> 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.       >>>       >>       >> Then how do you explain the alternator can charge the battery with no       >> apparently DC current output?       >>       > I can explain it but the issue is with you understanding it. A WOFTAM.       >                     It is very simple that you are full of shit. If the alternator has DC       output then inserting a DC ammeter like the OP did should register DC       current. You simply cannot think outside the box.              Come on. Make my day. Explain why there is no apparent DC current coming       out of the alternator but it can charge the battery.              Take you time, here =====>              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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