Majestic
Well-Known Member
Ok found it had a bad connection going to coil. Started and drove down road with new regulator hooked up and came back and have 14.49 volts on battery while running.
A 12 volt draw on battery from a one wire alternator
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Majestic
Well-Known Member
Alternator is putting out 15
Majestic
Well-Known Member
15 volts at idle on battery. Gonna leave it tonight and see if the battery stays charged.
Majestic
Well-Known Member
Battery stayed charged but worried it may be overcharging. It is reading 15.3 volts while idling. I think this is gonna fry the battery. Any ideas
67Dart273
Well-Known Member
I hate to complicate this as much grief as you've had but the no1 cause of overvoltage is that the VR is getting too LOW voltage through the harness, in other words "voltage drop."
In an original car/ original harness, the voltage feed from battery to VR goes: (function, not electron flow)
battery.........starter relay........fuse link.........bulkhead connector (RED).......ammeter........out ammeter on BLACK........branch off to ignition switch connector........through switch.......back out connector on IGN 1 "run" (DARK BLUE)........out bulkhead connector.........branch off to ignition, VR, alternator field
Each one of those terminal points.........bulkhead connector......ammeter terminals and ammeter..........switch connector and switch..........etc. etc
is a place for a voltage drop, and can be one or all of them.
To find out...........Turn key to "run" with engine off
Stab one probe of your meter onto the battery POS post. Hook the other probe to "same as" VR "ign" wire, IE where your ballast branches off, or the blue at the alternator field. Don't disconnect anything, hook this up "ready to run."
Measure that, on low volts. You are hoping for a VERY low reading the lower the better. each tenth of a volt you read ADDS to the charging voltage
This means...........that if the VR is properly regulating (warm) at 13.8---14.2, the voltage drop you read there (say .8V) ADDS to the charging voltage, IE 14.2 + .8V is 15V!!!!!
The other issue can be GROUNDING. The VR mounting (ground) MUST be at the same potential as battery NEG post. Same deal........voltage drop.
To measure this, check with engine running to simulate "medium cruise" and check with all loads shut off, and with loads, like headlights, heater, etc, running.
Stab one probe of your meter onto the battery NEG post, and the other onto the VR mounting flange. Be sure to stab through paint, rust, etc. AGAIN, you are looking for "the lower the better," zero volts would be perfect
In an original car/ original harness, the voltage feed from battery to VR goes: (function, not electron flow)
battery.........starter relay........fuse link.........bulkhead connector (RED).......ammeter........out ammeter on BLACK........branch off to ignition switch connector........through switch.......back out connector on IGN 1 "run" (DARK BLUE)........out bulkhead connector.........branch off to ignition, VR, alternator field
Each one of those terminal points.........bulkhead connector......ammeter terminals and ammeter..........switch connector and switch..........etc. etc
is a place for a voltage drop, and can be one or all of them.
To find out...........Turn key to "run" with engine off
Stab one probe of your meter onto the battery POS post. Hook the other probe to "same as" VR "ign" wire, IE where your ballast branches off, or the blue at the alternator field. Don't disconnect anything, hook this up "ready to run."
Measure that, on low volts. You are hoping for a VERY low reading the lower the better. each tenth of a volt you read ADDS to the charging voltage
This means...........that if the VR is properly regulating (warm) at 13.8---14.2, the voltage drop you read there (say .8V) ADDS to the charging voltage, IE 14.2 + .8V is 15V!!!!!
The other issue can be GROUNDING. The VR mounting (ground) MUST be at the same potential as battery NEG post. Same deal........voltage drop.
To measure this, check with engine running to simulate "medium cruise" and check with all loads shut off, and with loads, like headlights, heater, etc, running.
Stab one probe of your meter onto the battery NEG post, and the other onto the VR mounting flange. Be sure to stab through paint, rust, etc. AGAIN, you are looking for "the lower the better," zero volts would be perfect
BillGrissom
Well-Known Member
I tried to wade thru the posts, but a bit confusing. The OP never told us the year of his car. It has a later (1971+) voltage regulator and square-back alternator.
I didn't see the thick ALT wire connected to the alternator's big output stud in any of the photos. This is the insulated stud. One alternator has a second ground stud and I saw a wire bolted to that. I hope that isn't the ALT wire since that would short BAT+ to ground, via the bulkhead connector and dash ammeter.
But, he is getting >15 V while driving, so the alternator must be outputting to BAT+ and not shorted. Re using a multimeter and basic electricity, there are many youtubes and wikipedia pages. Re monitoring while driving, get a cigarette-lighter voltmeter to use in addition to the dash ammeter (if that still works).
I didn't see the thick ALT wire connected to the alternator's big output stud in any of the photos. This is the insulated stud. One alternator has a second ground stud and I saw a wire bolted to that. I hope that isn't the ALT wire since that would short BAT+ to ground, via the bulkhead connector and dash ammeter.
But, he is getting >15 V while driving, so the alternator must be outputting to BAT+ and not shorted. Re using a multimeter and basic electricity, there are many youtubes and wikipedia pages. Re monitoring while driving, get a cigarette-lighter voltmeter to use in addition to the dash ammeter (if that still works).
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