69 corvette ammeter question?
Thread Starter
Instructor
Joined: Jul 2004
Posts: 232
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From: Langley B.C Canada
69 corvette volt meter question?
My ammeter seems to always jump up to about 42 volts, and fluxuates with the rpm of the motor, but never drops down. Is the regulator supposed to regulate the charge, so when the battery reaches full charge, then the volt meter will read slightly more than 12 volts during driving? 
Last edited by darrentpi; Mar 8, 2005 at 12:57 AM.
Team Owner
Joined: Jul 2004
Posts: 40,405
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From: Redondo Beach, California
My first guess has to be that your ammeter wiring has been modified. Has someone altered the wiring?
Let's say that you car is sitting in the driveway with a fully charged battery and the engine is not running and the ignition is off. Start the car. Immediately afterwards you will see the ammeter reading a positive current. That is the current that is recharging the battery after it cranked the engine that you just started. After the battery has been recharged, the ammeter reading will be "0". Even if you turn on your air conditioning, etc, the ammeter should continue to read "0" since the alternator will supply the required current.
There's a "fusible link"... a wire with a small resistance built in that runs from the alternator to the battery. (Actually the wire itself runs from a lug on the horn relay ..the lug is directly connected to the alternator output...and the other end of the fusibible link is on a starter solenoid terminat that is directly connected to the battery.) The "ammeter" is really a voltmeter and one end of the "ammeter" is connected to the horn relay lug (alternator output) and the other end of the "ammeter" wire is connected to the starter solenoid terminal that is connected directly to the battery.
When the ammeter is wired in it's factory configuration, it only measures battery charge current and battery discharge current. If you've got a sufficient alternator current output (amps), you can be driving with both electric SPALS on, the air con blower can be on high, the headlights can be on high, your radio can be on full blast, ...and the ammeter will be reading "0". .... If the alternator is supplying full electrical power and the battery is charged, the ammeter will read "0."
Let's say that you car is sitting in the driveway with a fully charged battery and the engine is not running and the ignition is off. Start the car. Immediately afterwards you will see the ammeter reading a positive current. That is the current that is recharging the battery after it cranked the engine that you just started. After the battery has been recharged, the ammeter reading will be "0". Even if you turn on your air conditioning, etc, the ammeter should continue to read "0" since the alternator will supply the required current.
There's a "fusible link"... a wire with a small resistance built in that runs from the alternator to the battery. (Actually the wire itself runs from a lug on the horn relay ..the lug is directly connected to the alternator output...and the other end of the fusibible link is on a starter solenoid terminat that is directly connected to the battery.) The "ammeter" is really a voltmeter and one end of the "ammeter" is connected to the horn relay lug (alternator output) and the other end of the "ammeter" wire is connected to the starter solenoid terminal that is connected directly to the battery.
When the ammeter is wired in it's factory configuration, it only measures battery charge current and battery discharge current. If you've got a sufficient alternator current output (amps), you can be driving with both electric SPALS on, the air con blower can be on high, the headlights can be on high, your radio can be on full blast, ...and the ammeter will be reading "0". .... If the alternator is supplying full electrical power and the battery is charged, the ammeter will read "0."
Team Owner
Joined: Jul 2004
Posts: 40,405
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From: Redondo Beach, California
Originally Posted by darrentpi
then the ammeter will read slightly more than 12 volts during driving?
Melting Slicks
Joined: May 2004
Posts: 2,501
Likes: 510
From: Willowbrook IL
St. Jude Donor '13-'14-'15-'16
The ammeter really does not read amps. It is a differential volt meter. It shows the diffeence between the alternator output voltage and the system voltage.
Thread Starter
Instructor
Joined: Jul 2004
Posts: 232
Likes: 2
From: Langley B.C Canada
Sorry guys, you are all right I guess I ment volt meter, I don't know where I got the ameter from. It just seems to always be charging at full scale deflection, almost 42 volts all the time, when it should back off as the batttery becomes charged.
Thanks,
Darren
Thanks,
Darren
Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
The ammeter does not read volts.
What is does read is a differential voltage that is expressed as amps. This shows the relative amount of charge or discharge going in the system.
After you start the engine, the ammeter will read high as the battery is being recharged. It should then drop down close to zero or a slight charge. If your's is showing a constant charge, then I would do the following:
1) Check your connections
2) Have battery tested
3) Have alternator tested
4) Replace bad components.
What is does read is a differential voltage that is expressed as amps. This shows the relative amount of charge or discharge going in the system.
After you start the engine, the ammeter will read high as the battery is being recharged. It should then drop down close to zero or a slight charge. If your's is showing a constant charge, then I would do the following:
1) Check your connections
2) Have battery tested
3) Have alternator tested
4) Replace bad components.
