John431 Posted August 4, 2020 Report Share Posted August 4, 2020 Howdy y'all My charging saga continues ! With my 1947 Dodge club coupe 6v pos grnd flat 6 cyl.. In my other post I had mentioned my problem with Generator charging system...so I decided to go with alternator swap. (6v pos grnd) Here are the problems...ammeter reads full negative charge wth engine running...The battery (engine off) reads 6.23v Testing alternator (Engine running) 6.47v at idle...if i disconnect pos battery cable engine still runs fine. with everything connected...i get Fluctuating voltage readings with multimeter....I am at a loss as to what the problem is with such a "simple" system...I purchased the alternator from Bill on Ebay (very helpful guy) but he as well is "stumped" as to what the issue could be...so...any info, suggestions Would be greatly appreciated. Thanks, John Quote Link to comment Share on other sites More sharing options...
50mech Posted August 4, 2020 Report Share Posted August 4, 2020 (edited) How is it wired in? Sounds like the charge wire is run to the battery. Not correct for an ammeter. Edited August 4, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
50mech Posted August 4, 2020 Report Share Posted August 4, 2020 (edited) Anyway the charge wire should be hooked to the wire that used to go on the bat terminal of your VR. Depending on the alternator you may or may not need a jumper on the alternator from the charging terminal over to the #2 terminal in the slot on the side of it. Edited August 4, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
John431 Posted August 4, 2020 Author Report Share Posted August 4, 2020 Thanks for quick response ! Anyway I wired as per the gentleman(Bill ebay)that sold the kit to me : wire from alt to bat terminal on old V.R which goes back to the ammeter. I then eliminated the V.R completely and wired them directly together...with that...the ammeter still reads almost full discharge and when engine is running I get rapid fluctuating voltage readings...my guess is something must be reversed. is it possible that the gauge is wired in reverse ? I also notice that the coil was wired reversed I switched that with no success. Being this is "allegedly" a very simple system I'm stumped...any ideas as to possible problem ? Thanks again for info and quick response !!!! John. Quote Link to comment Share on other sites More sharing options...
50mech Posted August 5, 2020 Report Share Posted August 5, 2020 (edited) Well, might sound dumb but is the positive battery cable running to the block and neg to the starter? I know, I apologise if it seems overly simple but it's one of those " ya never know" questions and looking at your previous thread it really seems like the battery may be hooked up backwards. Edited August 5, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
John431 Posted August 5, 2020 Author Report Share Posted August 5, 2020 Yes...battery cables connected properly for pos grnd system...something wierd going on...I'm thinking maybe ammeter or ign switch ? Thanks, John Quote Link to comment Share on other sites More sharing options...
Sniper Posted August 5, 2020 Report Share Posted August 5, 2020 The ammeter doesn't magically switch polarity, so unless you swapped the wires around something else is amiss, like you didn't get a positive ground alternator or something along those lines. Which, if the wrong polarity alternator was shipped ot you would stop using it immediately. Just spitballing here though, can you confirm with a meter that the alternator is putting out the correct polarity? Quote Link to comment Share on other sites More sharing options...
50mech Posted August 5, 2020 Report Share Posted August 5, 2020 (edited) If it was the ammeter it would just read backwards... wouldn't cause any other issue. Outside of snipers suggestion. Possibly something is tripping the 30 amp breaker, causing the cyclic readings. So something reverse polarity or a dead short. You could disconnect the breaker but leave the two brown ignition and ammeter wires connected together and disconnect cigar lighter from ammeter. That would isolate the charging system. Also check to be certain all wiring is on the proper side of the starter solenoid. Edited August 5, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
50mech Posted August 5, 2020 Report Share Posted August 5, 2020 (edited) Oops wrong year, ignore that part about the CB. I'll look at the right diagram and rethink it. Edited August 5, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
50mech Posted August 5, 2020 Report Share Posted August 5, 2020 (edited) Delete. Edited August 5, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
50mech Posted August 5, 2020 Report Share Posted August 5, 2020 (edited) So if the alt checks out I guess 1. Maybe the ammeter has always been wired backwards, or even just has the bat wire on the same side as the alternator wire. 2. You can start looking for this short causing a 40amp draw. I guess I would start by confirming the correct ammeter wiring then disconnecting the ammeter to ignition switch wire, then running a jumper from bat to ign coil with the coil disconnected and using a jumper to the solenoid to start it. That isolates everything that's on in run position. See how it acts then. Edited August 5, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 Hi everybody, Ok...I think I might have made progress....reversed wires on the ammeter...now showing "plus" when running (hoo-ray) BUT....the needle advances more when I put headlights on (Is that normal?) AND I still get rapid fluctuating readings on multimeter at battery only while running (poss bad battery ?) Another thing I noticed that caught my attention is with engine running, headlights on, if I disconnect the pos battery cable the lights get brighter, and the engine still runs fine. Thoughts, tips comments please Thank you for all the help so far !!!! John. Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 Also....should I have current flowing "to" the alternator lug ? I have alternator wire connected to the old "bat" lead which goes back to the ammeter...just a f.y.i...I only get flucuating volatge readings with multimeter when engine is running...otherwise all "seems" ok John Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 6, 2020 Report Share Posted August 6, 2020 (edited) If you are using a digital multimeter you may get jerky readings. Sometimes the digital meter and alternator voltage regulator don't get along very well. If you have an analog meter it may give a steady reading. The lights may be getting brighter with a disconnected battery because the alternator is trying to charge a very dead battery....... The battery serves as a sump to dampen voltage surges...I wouldn't mess around with a disconnected battery with the solid-state regulator in the alternator. The needle is showing more current with lights on because.......the lights are drawing more current........that is what an ammeter does..... Edited August 6, 2020 by Sam Buchanan 1 Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 I think I'm getting closer to a solution!!! One more "clue" to this mystery... When I put just the black (neg) probe from the multimeter on the neg battery post voltage reading fluctuates rapidly...I find that kinda odd. Thanks again to all I appreciate all the help !!! John Quote Link to comment Share on other sites More sharing options...
50mech Posted August 6, 2020 Report Share Posted August 6, 2020 (edited) 13 hours ago, John431 said: I think I'm getting closer to a solution!!! One more "clue" to this mystery... When I put just the black (neg) probe from the multimeter on the neg battery post voltage reading fluctuates rapidly...I find that kinda odd. Thanks again to all I appreciate all the help !!! John Haha, it's picking up radio noise from the ignition. If you have a fancy schmancy meter make sure it's set to read voltage RMS Edited August 6, 2020 by 50mech Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 Ha...fancy schmancy ??? Nope "Harbor fruit" I hope it something as silly as that, (radio noise) otherwise it seems to be making sense now since I reversed wires on ammeter, just those "wonky" multimeter readings bother me.(only when its running) So I think I might be headed in the right direction, I'm going to rewire the ign switch as per the manual schematic "Fingers crossed" Thanks for that tidbit of info !!!!!! John 1 Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 Well still no luck resolving fluctuating voltage readings(when engine running) reconnected wiring as per manual. It seems to be "working/charging" I'm running out of ideas...nothing hot/ burning, blowing up etc...should I just call it a day and leave it or.....is there more to this "mystery "I'm not seeing ? Faulty gauge, coil, ign switch ? All wires seemn to check out. Go figure...only a handful of wires in the entire car and I have a problem, good grief !!!! Thanks John Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 6, 2020 Report Share Posted August 6, 2020 (edited) I'll say this again......a cheap multimeter (I use the Habba Fright meter all the time) can show flaky voltage readings due to ignition noise on our charging systems. I've seen it and the charging system in my car (alternator) is rock solid. The noise is sufficient to make the little LED I use for the turn signal indicator flicker all the time. I pulled up to my friend's hangar when he had his aircraft radio turned on and you wouldn't believe the racket my P15 was transmitting to his poor radio (non-resistor plugs and solid copper wires). Drive your car. If the battery stays charged the alternator is doing what it is supposed to be doing. Edited August 6, 2020 by Sam Buchanan 1 Quote Link to comment Share on other sites More sharing options...
John431 Posted August 6, 2020 Author Report Share Posted August 6, 2020 I think you are right !!! Outside of the multimeter everything seems to be good ! So "Success"? I think so. Thanks to all of you for your support, info, suggestions and advice !!!!!!! Thanks !!!!!! John (My multimeter) Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 6, 2020 Report Share Posted August 6, 2020 Measure the battery voltage with the engine off and if you see around 6.5v the battery is holding a good charge. Quote Link to comment Share on other sites More sharing options...
maok Posted August 6, 2020 Report Share Posted August 6, 2020 What is your idle speed? Are you showing charge on the ammeter at idle? The alternator may not be spinning faster enough at idle, you may need a smaller pulley on the alternator. Quote Link to comment Share on other sites More sharing options...
John431 Posted August 7, 2020 Author Report Share Posted August 7, 2020 Not sure of rpms BUT ! at the moment charging system seems to be functioning properly. (Hallelujah) Thanks ! John Quote Link to comment Share on other sites More sharing options...
John431 Posted August 7, 2020 Author Report Share Posted August 7, 2020 Next is Pertronix install hopeing to clear up a "stumble above idle, smooth at idle then starts to sputter above that (God help me!) : ) John Quote Link to comment Share on other sites More sharing options...
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