charging
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Intermediate
Joined: Nov 2017
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charging
got a 78 coupe and at start up the alternator gauge shows a discharge but after a few minutes it swings back to charge
is this just a remove and replace the alternator or is there something else i should be looking for?
Any help would be appreciated
is this just a remove and replace the alternator or is there something else i should be looking for?
Any help would be appreciated
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From: New Or-leens Loo-z-anna
FIRST....Don't start buying parts yet! It could be a DIY fixable problem.
Clean both batter terminals and clean the area where the negative cable bolts to the frame.
(IF there is green corrosion on the battery cables, they may be bad and need replacing.)
Then....Let your local Auto Parts store perform a crank test on the battery to see if it is going bad.
Let us know what you discover.
Clean both batter terminals and clean the area where the negative cable bolts to the frame.
(IF there is green corrosion on the battery cables, they may be bad and need replacing.)
Then....Let your local Auto Parts store perform a crank test on the battery to see if it is going bad.
Let us know what you discover.
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Dont rely on the stock gauge, hook up a multimeter and verify it either isnt charging or is discharging. Could be anything from a bad gauge, loose grounds, loose alternator wires, bad wire plug, bad battery ground or positive cable connection....etc....
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From: Virginia
Post some pictures!
A stock 78 has a voltmeter on the dash. Are you using that as a reference, or is there an ammeter in its place?
If a PO has installed a 1-wire alternator, who knows what's going on now, but sometimes they need to get "excited" by high RPMs before they output anything at all.
A stock 78 has a voltmeter on the dash. Are you using that as a reference, or is there an ammeter in its place?
If a PO has installed a 1-wire alternator, who knows what's going on now, but sometimes they need to get "excited" by high RPMs before they output anything at all.
2026 Loser of the Year
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From: New Or-leens Loo-z-anna
Like the members said...connect a multimeter to the battery terminals before turning the key on.
Check the reading with the key on,
then watch the meter as you turn the key to crank the engine,
and watch the meter as the engine runs for a few minutes.
Let us know the results.
Check the reading with the key on,
then watch the meter as you turn the key to crank the engine,
and watch the meter as the engine runs for a few minutes.
Let us know the results.
Racer
Joined: Oct 2018
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From: England
I have a 78 as well and it does just the same. I just need to give the throttle a blip and it starts charging. It's done this for the past 4 years since I completed a full restoration and I know that all the battery and earth connections are good. I suspect it is some sort of foible of the diode pack.
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Thread Starter
Intermediate
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13.31 battery voltage
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
Racer
Joined: Sep 2011
Posts: 381
Likes: 90
From: Portland, the original!
I have a 78 as well and it does just the same. I just need to give the throttle a blip and it starts charging. It's done this for the past 4 years since I completed a full restoration and I know that all the battery and earth connections are good. I suspect it is some sort of foible of the diode pack.
Race Director
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From: Virginia
13.31 battery voltage
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
Someone may chime in. Does your "Gen" light ever illuminate? As long as you blip the throttle, things seem to be working properly, and your alternator just needs a bit of time to start charging your battery. I wouldn't worry about it just yet.
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Yes, How it should work. Key on but not yet running, gen. light should light up. Turn key to start. As soon as the engine catches the gen. light should go out.
If the gen. light bulb has burnt out or has a bad connection the "Kick start" Voltage isn't being supplied to your Alternator. After a rev of the engine it's exciting itself. But that's not correct.
If the gen. light bulb has burnt out or has a bad connection the "Kick start" Voltage isn't being supplied to your Alternator. After a rev of the engine it's exciting itself. But that's not correct.
Racer
Joined: Oct 2018
Posts: 456
Likes: 131
From: England
Yes, How it should work. Key on but not yet running, gen. light should light up. Turn key to start. As soon as the engine catches the gen. light should go out.
If the gen. light bulb has burnt out or has a bad connection the "Kick start" Voltage isn't being supplied to your Alternator. After a rev of the engine it's exciting itself. But that's not correct.
If the gen. light bulb has burnt out or has a bad connection the "Kick start" Voltage isn't being supplied to your Alternator. After a rev of the engine it's exciting itself. But that's not correct.
Race Director
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Interesting, internal fault in the alternator. Most likely that little resistor. I would put a kit through that Alternator.
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
13.31 battery voltage
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
13.25 ignition on
10.50 engine cranking
12.26 1500 RPM
14.55 1100 RPM
14.30 idle
after a few minutes of running it"s like ukjohn says a little throtle hit and jumps back to show charge
looks as though the alternator is working, must be that dash voltmeter.
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,559
Likes: 7,006
From: New Or-leens Loo-z-anna
The battery then began to drain down in a few days.
Disconnecting the 12V wire to the alt. kept the battery from draining down.
I installed the kit and the alt worked fine....no more battery drain/didn't have to disconnect the alt. while the car was not driven.
Race Director
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From: Virginia
I'm wondering if the behavior is explained by a burnt out "GEN" bulb. It's easy enough to take the alternator in to test. But it works and charges to 14.5V. If it were my car, I wouldn't touch it. I would check the bulb, though.
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
True....always replace the least expensive part first....if you can reach it.
Thread Starter
Intermediate
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Race Director
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From: Sunshine Coast, Queensland, Australia
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A fair few of us don't think that's really a great idea. And DO NOT put a LED in that gen. light socket! Then you may as well leave it as is. Not working.
A LED is a Light Emitting Diode. A Diode flows current one way. This will disable your generator lights function. A REALLY bad place for a LED.
A LED is a Light Emitting Diode. A Diode flows current one way. This will disable your generator lights function. A REALLY bad place for a LED.