Still having electrical problem, HELP ! !
Thread Starter
Racer
Joined: Jan 2009
Posts: 462
Likes: 1
From: Westernport Maryland
Still having electrical problem, HELP ! !
1980 model which got a new motor installed. Used a new 140 amp. one wire alternator and can't get the thing to charge. Ran a parallel hot and ground wire to the battery. Once in a while when it starts it will spike the ammeter to 14 v. then drop to under 13 v. Alternator tested good low load 13.7 v. high load 16.2 v. In the car at battery with motor not running 11.77 v. at alt. 11.75 v. Running at bat. 11.57 and at alt. 11.5 v. Running under load at alt. 11.11v reved motor 11.35 v. at alt. Checked the grounds even cleaned the one under the battery on the crossmember. What the ??????? is going on? I don't have that much hair to pull out, help.
Instructor
Joined: Apr 2011
Posts: 161
Likes: 17
From: NW CT
Take your volt meter.
Set it for volts
Take the red probe and stick it on the B+ terminal of the alt. Take the black probe and stick it to the the + of the battery. Stab it right in to the lead terminal on the battery. Dont go to the cable or bolt. Should read zero volts.
Now take the probes and go between the case of the alt and the lead on the - of the battery. Should also read zero.
If you are reading voltage then you have a bad cable or bad connection.
Another check would be to compare the readings between the B+ and case on the alt and the + and - on the battery. They should be the same. If you got 11.something on the battery and 16.something on the alt then you have a bad connection.
IF everything is the same then you have an alt issue
Are you SURE this is set up for 1 wire?
Set it for volts
Take the red probe and stick it on the B+ terminal of the alt. Take the black probe and stick it to the the + of the battery. Stab it right in to the lead terminal on the battery. Dont go to the cable or bolt. Should read zero volts.
Now take the probes and go between the case of the alt and the lead on the - of the battery. Should also read zero.
If you are reading voltage then you have a bad cable or bad connection.
Another check would be to compare the readings between the B+ and case on the alt and the + and - on the battery. They should be the same. If you got 11.something on the battery and 16.something on the alt then you have a bad connection.
IF everything is the same then you have an alt issue
Are you SURE this is set up for 1 wire?
Last edited by ConnecticutJunkman; Jul 9, 2014 at 11:59 PM.
Pro
Joined: Nov 2013
Posts: 730
Likes: 37
From: Catoosa Okla
Take your volt meter.
Set it for volts
Take the red probe and stick it on the B+ terminal of the alt. Take the black probe and stick it to the the + of the battery. Stab it right in to the lead terminal on the battery. Dont go to the cable or bolt. Should read zero volts.
Now take the probes and go between the case of the alt and the lead on the - of the battery. Should also read zero.
If you are reading voltage then you have a bad cable or bad connection.
Another check would be to compare the readings between the B+ and case on the alt and the + and - on the battery. They should be the same. If you got 11.something on the battery and 16.something on the alt then you have a bad connection.
IF everything is the same then you have an alt issue
Are you SURE this is set up for 1 wire?
Set it for volts
Take the red probe and stick it on the B+ terminal of the alt. Take the black probe and stick it to the the + of the battery. Stab it right in to the lead terminal on the battery. Dont go to the cable or bolt. Should read zero volts.
Now take the probes and go between the case of the alt and the lead on the - of the battery. Should also read zero.
If you are reading voltage then you have a bad cable or bad connection.
Another check would be to compare the readings between the B+ and case on the alt and the + and - on the battery. They should be the same. If you got 11.something on the battery and 16.something on the alt then you have a bad connection.
IF everything is the same then you have an alt issue
Are you SURE this is set up for 1 wire?
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Most new alternators are self exciting. Just rev the engine over 2000 rpm a few times.
You battery voltages seems very low. It should be 12.3-12.7 this might explain the 16volts . Drive it for awhile and the alternator voltage should slowly drop to 13 volts over an hour of cruising. If it stays high, above 14.5 volts. I would say try a different battery.
Your battery may be strong enough to crank the motor over but if it can't maintain or get to that 12.3 volts, the alt will think the battery is run down. That causes the regulator to go wide open on the power pumping voltage to it
You battery voltages seems very low. It should be 12.3-12.7 this might explain the 16volts . Drive it for awhile and the alternator voltage should slowly drop to 13 volts over an hour of cruising. If it stays high, above 14.5 volts. I would say try a different battery.
Your battery may be strong enough to crank the motor over but if it can't maintain or get to that 12.3 volts, the alt will think the battery is run down. That causes the regulator to go wide open on the power pumping voltage to it
Instructor
Joined: Apr 2011
Posts: 161
Likes: 17
From: NW CT
Most new alternators are self exciting. Just rev the engine over 2000 rpm a few times.
You battery voltages seems very low. It should be 12.3-12.7 this might explain the 16volts . Drive it for awhile and the alternator voltage should slowly drop to 13 volts over an hour of cruising. If it stays high, above 14.5 volts. I would say try a different battery.
Your battery may be strong enough to crank the motor over but if it can't maintain or get to that 12.3 volts, the alt will think the battery is run down. That causes the regulator to go wide open on the power pumping voltage to it
You battery voltages seems very low. It should be 12.3-12.7 this might explain the 16volts . Drive it for awhile and the alternator voltage should slowly drop to 13 volts over an hour of cruising. If it stays high, above 14.5 volts. I would say try a different battery.
Your battery may be strong enough to crank the motor over but if it can't maintain or get to that 12.3 volts, the alt will think the battery is run down. That causes the regulator to go wide open on the power pumping voltage to it
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
save your hair, install the correct 3 wire alternator.
the point of the 3 wire is so it can properly sense voltage and adjust charging accordingly.
1 wire is made for rods and boats and such, you car has the proper sense wiring built into it,
use it.
the point of the 3 wire is so it can properly sense voltage and adjust charging accordingly.
1 wire is made for rods and boats and such, you car has the proper sense wiring built into it,
use it.
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Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
plug it into the correct alternator. this is the problem.
taking for Diagnostic will be waste of time/money.
any decent electrical repair shop will tell you,
to fix your charging problems put the right alternator on it.
taking for Diagnostic will be waste of time/money.
any decent electrical repair shop will tell you,
to fix your charging problems put the right alternator on it.
Team Owner
Joined: Sep 2013
Posts: 36,415
Likes: 6,905
From: New Or-leens Loo-z-anna
Follow the instructions when installing the new alternator to keep from shorting out the internal wiring....and be sure to charge the battery for several hours BEFORE installing the new alternator.
(don't ask......
)
and be sure to charge the battery for several hours BEFORE installing the new alternator so it will get "excited" and will charge correctly.
(don't ask, again...... )
(don't ask......
)and be sure to charge the battery for several hours BEFORE installing the new alternator so it will get "excited" and will charge correctly.
(don't ask, again......
)
Last edited by doorgunner; Jul 12, 2014 at 03:12 PM.
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
so with this new alternator connected all non-Original wiring removed, test 2 things.
1 what is the voltage on the output of the alternator with the engine running above 1500rpm ?
another easy test on the alternator, on the back in the center where the center bearing is located, if your alternator is working and generating current, the center area will become slightly magnetic, stick a metal something at the back of the alternator does the magnetic field pull metal object, if it does you have an open charging circuit, very possible right at your amp meter in the dash/console.
1 what is the voltage on the output of the alternator with the engine running above 1500rpm ?
another easy test on the alternator, on the back in the center where the center bearing is located, if your alternator is working and generating current, the center area will become slightly magnetic, stick a metal something at the back of the alternator does the magnetic field pull metal object, if it does you have an open charging circuit, very possible right at your amp meter in the dash/console.
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
voltage at alternator ? correct ? not battery.
what is alternator voltage and what is battery voltage to Gnd. not to battery gnd.post.
magntic indicates magnetic feild is being generated = charging.
need schematic to follow I beleive it goes straight to AMPmeter, then thru meter and shunt,
sometimes these open, which would prevent charge from getting to the battery.
what does your ampmeter do ?
what is alternator voltage and what is battery voltage to Gnd. not to battery gnd.post.
magntic indicates magnetic feild is being generated = charging.
need schematic to follow I beleive it goes straight to AMPmeter, then thru meter and shunt,
sometimes these open, which would prevent charge from getting to the battery.
what does your ampmeter do ?
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
voltage at alternator ? correct ? not battery.
what is alternator voltage and what is battery voltage to Gnd. not to battery gnd.post.
magntic indicates magnetic feild is being generated = charging.
need schematic to follow I beleive it goes straight to AMPmeter, then thru meter and shunt,
sometimes these open, which would prevent charge from getting to the battery.
what does your ampmeter do ?
what is alternator voltage and what is battery voltage to Gnd. not to battery gnd.post.
magntic indicates magnetic feild is being generated = charging.
need schematic to follow I beleive it goes straight to AMPmeter, then thru meter and shunt,
sometimes these open, which would prevent charge from getting to the battery.
what does your ampmeter do ?
Not meaning to be a smart a$$...but reading your posts are sometimes really hard to do. You have great tips/advice but maybe reading over them before posting them. UNLESS it is just me.
DUB
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
my mistake I failed to read he had later model C3, thanks for the correction.
it is also why, I suggested following a schematic.
I attempt to assit people asking for help,
instead of trying to see who is the funniest off-Topic poster.
(not referring to you or this Thread)
back to OP
I think your alternator is Charging, I suspect you have an open in the charging circuit,
from the Alternator to the Battery.
it is also why, I suggested following a schematic.
I attempt to assit people asking for help,
instead of trying to see who is the funniest off-Topic poster.
(not referring to you or this Thread)
back to OP
I think your alternator is Charging, I suspect you have an open in the charging circuit,
from the Alternator to the Battery.
