Carburetor fan possibly drains battery below 12v - ever happen to anyone else?

tvmaster

True Classic
Good information. Now, if you reconnect the red connector to the D+ terminal on the alternator, does the "G" light turn on when you turn on the ignition? If you tug gently on the PRP/WHT wire, move it around a bit etc, does the light flicker / turn off / turn on?

Do you own a test light? Something like this? Note that this is the kind that does not use a battery (the type with a battery looks similar, but is usually called a continuity tester). If you do, unplug the red connector from the D+ terminal on the alternator. Clip the alligator clip on the test light to the fat B+ output on the back of the alternator, and touch the tip of the tester to the D+ terminal on the alternator. The test light should light up, and if it does not you can be quite certain the voltage regulator has gone bad.
Thanks - I do not own a test light, but if this isn't the dandiest reason to buy one, I don't know what is :) Wiggling the wire around didn't seem to do much, although, the connector attached to the B+ terminal feels a little suspect, possibly broken metal under the plastic sheath.
If the B+ wire were broken, would the result be as it is now, really low charging numbers and a dead 'G' light?
There's no heat shield near the alternator (original long since gone I guess). I was mildy concerned engine heat may damage the internal regulator. Time will tell. Thanks
 

Dan Sarandrea (Phila)

Waitin' On Parts...
Touching the red connector to ground and having it light the lamp proves that the side of the circuit from the connector thru the wiring to the lamp, thru the lamp, thru the ignition switch, and back to the battery is in reasonable enough condition.

(Essentially what you did was use the G light as a test light.)

I would submit that the next test would be, after acquiring a test light, is to confirm that you have good connectivity between the battery and the B+ stud on the back of the alt. Even though you'll do this one with the ignition off, this is an always-hot circuit, so just keep that in mind and be careful. Clip the neg side of the test light to a handy ground and then touch the test probe to the B+ stud. The test light should illuminate, demonstrating that there is electricity flow from the battery that's making it all the way back to the B+ stud.

Extra credit tests
Now do the same thing with your multimeter set on volts (20v DC if you have that range). Red to the B+ stud on the back of the alt and black to a handy ground. The resulting voltage number will tell you how many volts are getting thru the wiring from the batt back to the B+ stud on the alt. Compare to a direct reading from the battery itself to find how much of a voltage loss you have.

Theoretical example:
Reading directly from battery posts: 12.7v
Reading from the B+ stud on the back of the alternator: 12.3v
Voltage loss = 0.4v

The voltage drop tests you see on help sites and YouTube are oriented to testing starters, so don't pay attention to that just yet, let's just see what your numbers are for the batt to B+ wire path.


If you had really long leads, another test would be to set the meter for resistance (Ohms) and connect one multimeter lead to the battery Pos terminal and the other to the B+ stud on the alt, which would measure the resistance in that particular leg of circuit. The lower this number the better.

IMO, now you're ready to do Bjorn's test in post #100 above.
 
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tvmaster

True Classic
Good information. Now, if you reconnect the red connector to the D+ terminal on the alternator, does the "G" light turn on when you turn on the ignition? If you tug gently on the PRP/WHT wire, move it around a bit etc, does the light flicker / turn off / turn on?

Do you own a test light? Something like this? Note that this is the kind that does not use a battery (the type with a battery looks similar, but is usually called a continuity tester). If you do, unplug the red connector from the D+ terminal on the alternator. Clip the alligator clip on the test light to the fat B+ output on the back of the alternator, and touch the tip of the tester to the D+ terminal on the alternator. The test light should light up, and if it does not you can be quite certain the voltage regulator has gone bad.
Test light DOES NOT light up.
:(
 

tvmaster

True Classic
Touching the red connector to ground and having it light the lamp proves that the side of the circuit from the connector thru the wiring to the lamp, thru the lamp, thru the ignition switch, and back to the battery is in reasonable enough condition.

(Essentially what you did was use the G light as a test light.)

I would submit that the next test would be, after acquiring a test light, is to confirm that you have good connectivity between the battery and the B+ stud on the back of the alt. Even though you'll do this one with the ignition off, this is an always-hot circuit, so just keep that in mind and be careful. Clip the neg side of the test light to a handy ground and then touch the test probe to the B+ stud. The test light should illuminate, demonstrating that there is electricity flow from the battery that's making it all the way back to the B+ stud.

Extra credit tests
Now do the same thing with your multimeter set on volts (20v DC if you have that range). Red to the B+ stud on the back of the alt and black to a handy ground. The resulting voltage number will tell you how many volts are getting thru the wiring from the batt back to the B+ stud on the alt. Compare to a direct reading from the battery itself to find how much of a voltage loss you have.

Theoretical example:
Reading directly from battery posts: 12.7v
Reading from the B+ stud on the back of the alternator: 12.3v
Voltage loss = 0.4v

The voltage drop tests you see on help sites and YouTube are oriented to testing starters, so don't pay attention to that just yet, let's just see what your numbers are for the batt to B+ wire path.


If you had really long leads, another test would be to set the meter for resistance (Ohms) and connect one multimeter lead to the battery Pos terminal and the other to the B+ stud on the alt, which would measure the resistance in that particular leg of circuit. The lower this number the better.

IMO, now you're ready to do Bjorn's test in post #100 above.
Test 1: light lit, so there’s theoretically flow from the battery to B+ stud.

Test 2: 12.27v at battery, with surprisingly the SAME number at the B+ stud, therefore no loss of voltage. Checked it twice.

Test 3: Ohm resistance test. Meter set at 20k ohm. Readout = 0.87

Bjorn’s test did not produce a lit lantern. Just to make sure the tool worked I touched the tip to ground, and yes, the tool lit up then. But not when touched to the D+ terminal.

thoughts?
 
Test 1: light lit, so there’s theoretically flow from the battery to B+ stud.

Test 2: 12.27v at battery, with surprisingly the SAME number at the B+ stud, therefore no loss of voltage. Checked it twice.

Test 3: Ohm resistance test. Meter set at 20k ohm. Readout = 0.87

Bjorn’s test did not produce a lit lantern. Just to make sure the tool worked I touched the tip to ground, and yes, the tool lit up then. But not when touched to the D+ terminal.

thoughts?
Test 2 should show the same reading if it is a half way decent meter that has a high input impedance. You measured the resistance at 0.87 ohms. Using Ohm's Law, V=IR, you can see that if the meter is drawing in the microamp range, the difference in voltage is going to be microvolts. However, if the circuit is in operation with 0.87 ohms resistance, it will have a problem. For example, drawing 10 amps through 0.87 ohms gives you an 8.7V drop! Your wiring from the battery to the alternator looks to be a problem. If the motor cranks well, that could eliminate the wire from the battery to the starter from being the issue. That leaves the wire from the starter to the alternator as the possible culprit. I recommend getting the following resistance readings"

1. Battery + to starter stud resistance (disconnect battery)
2. Starter stud to alternator stud resistance (disconnect battery)

With that much resistance, your alternator may actually be trying to charge the battery but cannot due to the series resistance and the resulting voltage drop.
 

tvmaster

True Classic
Test 2 should show the same reading if it is a half way decent meter that has a high input impedance. You measured the resistance at 0.87 ohms. Using Ohm's Law, V=IR, you can see that if the meter is drawing in the microamp range, the difference in voltage is going to be microvolts. However, if the circuit is in operation with 0.87 ohms resistance, it will have a problem. For example, drawing 10 amps through 0.87 ohms gives you an 8.7V drop! Your wiring from the battery to the alternator looks to be a problem. If the motor cranks well, that could eliminate the wire from the battery to the starter from being the issue. That leaves the wire from the starter to the alternator as the possible culprit. I recommend getting the following resistance readings"

1. Battery + to starter stud resistance (disconnect battery)
2. Starter stud to alternator stud resistance (disconnect battery)

With that much resistance, your alternator may actually be trying to charge the battery but cannot due to the series resistance and the resulting voltage drop.
Car cranks and starts well, although I am having the starter, which was replaced last december, replaced again, as the gears usually grind when trying to engage. Mr. Old Fiat Guy, who sold and installed it, heard it last month and said "that doesn't sound good - I'll put in another one"
Sorry if I don't follow your math, it was never my thing. Wish it were though, as that's where all the money is these days....math.
All I know is I set the meter to 20k ohms (since Dan didn't specify a setting, merely "ohms"), and the number that came up was 0.87
The meter is by Ideal I believe. Hasn't given me trouble before...
 

Dan Sarandrea (Phila)

Waitin' On Parts...
The leads on my Craftsman meter aren't long enough to do the resistance check I suggested, so I would have to add an "extension" (in the form of temporarily rigged up 16- or 14-ga primary wire if I were going to do that test here. In that case, prior to doing the resistance test, it would be necessary to measure the resistance of the leads and the extension by touching the + and - lead together. The resultant number would be the baseline resistance that I would deduct from the number read when doing the batt-to-alt wire resistance check.

If you've ever worked in a field where things were weighed, you could call this the equivalent of a "tare" weight.
 
Car cranks and starts well, although I am having the starter, which was replaced last december, replaced again, as the gears usually grind when trying to engage. Mr. Old Fiat Guy, who sold and installed it, heard it last month and said "that doesn't sound good - I'll put in another one"
Sorry if I don't follow your math, it was never my thing. Wish it were though, as that's where all the money is these days....math.
All I know is I set the meter to 20k ohms (since Dan didn't specify a setting, merely "ohms"), and the number that came up was 0.87
The meter is by Ideal I believe. Hasn't given me trouble before...
You would likely get a more accurate reading if you set the resistance scale to as low a range as possible and measure the resistance of the cable from the battery to the alternator again. Hopefully, you will get a much lower number than 0.87 ohms. It is asking a bit much for that meter to resolve less than an ohm on a 20K ohm scale.
 

tvmaster

True Classic
The leads on my Craftsman meter aren't long enough to do the resistance check I suggested, so I would have to add an "extension" (in the form of temporarily rigged up 16- or 14-ga primary wire if I were going to do that test here. In that case, prior to doing the resistance test, it would be necessary to measure the resistance of the leads and the extension by touching the + and - lead together. The resultant number would be the baseline resistance that I would deduct from the number read when doing the batt-to-alt wire resistance check.

If you've ever worked in a field where things were weighed, you could call this the equivalent of a "tare" weight.
Good point. Of course I had to use alligator clips on the positive battery lead to reach. Probably 12/14 gauge wire three feet long.
 

tvmaster

True Classic
You would likely get a more accurate reading if you set the resistance scale to as low a range as possible and measure the resistance of the cable from the battery to the alternator again. Hopefully, you will get a much lower number than 0.87 ohms. It is asking a bit much for that meter to resolve less than an ohm on a 20K ohm scale.
Okay, what setting then?

6CE18EF4-2395-45B1-8BF1-C943C3B6E90A.jpeg
 

tvmaster

True Classic
Are you going to the 40-mile-away tech? How are you getting the car there without a functioning alternator?


View attachment 53864
Lol. Well that will be interesting, won’t it. No plans on stopping. No headlights, blower or a/c. How far do you think I can get? It charges to 12.07 volts at 3k rpm, and I can get the battery up to 12.65 with my charger in about an hour before I plan to leave. The trip takes about 40 minutes if all goes well.
 

ng_randolph

Bjorn H
Lol. Well that will be interesting, won’t it. No plans on stopping. No headlights, blower or a/c. How far do you think I can get? It charges to 12.07 volts at 3k rpm, and I can get the battery up to 12.65 with my charger in about an hour before I plan to leave. The trip takes about 40 minutes if all goes well.
Sounds dicey to me. Your last journey that ended with a stall in the driveway was what, 12 miles round trip? Had the battery been on a charger prior to that trip?
 

tvmaster

True Classic
Sounds dicey to me. Your last journey that ended with a stall in the driveway was what, 12 miles round trip? Had the battery been on a charger prior to that trip?
No, but that was two trips separated by an hour of the carb blower going. It is worth considering though. If the engine is running, being cooled by 65 mph speeds, what’s the alternator doing, essentially? The battery will get the car started, after that, I don’t think anything but the radio may be used?
 

ng_randolph

Bjorn H
No, but that was two trips separated by an hour of the carb blower going. It is worth considering though. If the engine is running, being cooled by 65 mph speeds, what’s the alternator doing, essentially? The battery will get the car started, after that, I don’t think anything but the radio may be used?
The ignition system draws a fair amount of current while driving. And I think once you have a working alternator, the carb fan problems will prove to have been a red herring.
 

tvmaster

True Classic
The ignition system draws a fair amount of current while driving. And I think once you have a working alternator, the carb fan problems will prove to have been a red herring.
hmmm. well, okay. I still have the 33 amp in a box. Maybe I’ll stick it back on first.
 

Dan Sarandrea (Phila)

Waitin' On Parts...
Lol. Well that will be interesting, won’t it. No plans on stopping. No headlights, blower or a/c. How far do you think I can get? It charges to 12.07 volts at 3k rpm, and I can get the battery up to 12.65 with my charger in about an hour before I plan to leave. The trip takes about 40 minutes if all goes well.
Do you have one of those rechargeable jumper boxes?

That plus a charged battery should get you to the mechanic. And lay off the stereo for this trip :)

https://www.harborfreight.com/630-peak-amp-portable-jump-starter-and-power-pack-58979.html
 
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