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Possible alternator issue

Rice154

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I have a 73 Charger with a stock 340 4 barrel. I am on my second battery in two years. I’ve noticed after driving the battery is weak. Car randomly dies when turning at low rpm’s, but starts up again right away ( no sputtering or choking out, dies as of key is turned off) I’ve put a multimeter to the alternator while running and get a little over 14 volts, but like I said above the battery does not seem to be getting a charge. I used a circuit tester and did not detect any shorts. I have also noticed that the battery drains while sitting in the garage. The headlights brighten when applying the gas and dim after letting off. I’ve recently replaced the voltage regulator and ECU. Not sure where else to look other than the alternator. Thanks in advance!
 
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If it's draining over night you have something drawing power off the battery. Pull the positive lead off the post and put an ammeter between the two to detect current draw.
 
That’s what I was thinking. If that’s the case, would I be able to detect that using a circuit tester?
 
What kind of circuit tester? Like a Power Probe? You should be able to use any multimeter in the DC current mode.
 
Yeah, i was using a probe. I didn’t make any progress. I think I’ll probably just swap out the alternator and see what happens.
 
I guess you could charge up the battery then disconnect the alternator overnight to see if that is the source of the drain.
 
Shorted diode might show a good charge when revved up, but not going slow. Trunk light,glove box, dome staying on?
 
Shorted diode might show a good charge when revved up, but not going slow. Trunk light,glove box, dome staying on?
Yeah, everything works, but headlights and dash lights do brighten and dim with acceleration which also makes me think alternator
 
Yeah, everything works, but headlights and dash lights do brighten and dim with acceleration which also makes me think alternator
That’s the way they all worked back in the day, w/o a bad diode!
 
If it's draining over night you have something drawing power off the battery. Pull the positive lead off the post and put an ammeter between the two to detect current draw.

That’s what I was thinking. If that’s the case, would I be able to detect that using a circuit tester?
Follow Chargers advice (you can even use a simple 12v test lamp between the battery cable and the post). Then pull the fuses one at a time. The fuse that extinguishes the test lamp is the offending circuit.
 
Follow Chargers advice (you can even use a simple 12v test lamp between the battery cable and the post). Then pull the fuses one at a time. The fuse that extinguishes the test lamp is the offending circuit.
Quite right,BUT have the doors shut when you do it or the door switch will turn on your test light.
 
Also, you can continue to check the voltage when increasing rpm and see what it does when rpm increases.
Not sure what alternator and regulator you are using, but max. voltage should be 14.4 volt at higher rpm's.
 
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