Voltmeter needle seems too high

[stevolwevol]

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My voltmeter in my 77 right after starting is almost to the line before the red zone. When I drive for a while it drops down a little, but it's beyond 13 volts. I do have an Accel Super coil, and maybe this requires more volts, but I don't know. Any input would be great.

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[Antz81]

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My voltmeter in my 77 right after starting is almost to the line before the red zone. When I drive for a while it drops down a little, but it's beyond 13 volts. I do have an Accel Super coil, and maybe this requires more volts, but I don't know. Any input would be great.

Its nothing to do with the coil.
first thought is the voltage regulator in the alternator is allowing the voltage to go too high.
but could also just be the gauge is faulty.
what's your battery voltage when you're getting this reading?

 

[LLC5]

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My voltmeter in my 77 right after starting is almost to the line before the red zone. When I drive for a while it drops down a little, but it's beyond 13 volts. I do have an Accel Super coil, and maybe this requires more volts, but I don't know. Any input would be great.

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Antz81 is spot on. Take a quality voltmeter and clip the leads to your battery terminals and check the voltage at idle and 2500 rpm's with the vehicle cold and hot. The factory gauges are not that accurate, they just tell you when you need to check a system properly. Good luck with it.

 

[Vettehead Mikey]

The readings sound perfectly normal to me (?)

 

[stevolwevol]

Well, I don't know if this is related to this issue, but after sitting a couple of days, the starter is slow as if my battery has been drained. After running, it starts fine. maybe I have something draining the battery when the ignition is off, or the new battery I bought in the spring is bad. The volt meter is still between 12 and 13 before I start the engine, but the starter sounds slow.

 

[stevolwevol]

Well, I don't know if this is related to this issue, but after sitting a couple of days, the starter is slow as if my battery has been drained. After running, it starts fine. maybe I have something draining the battery when the ignition is off, or the new battery I bought in the spring is bad. The volt meter is still between 12 and 13 before I start the engine, but the starter sounds slow.

Just to update the low battery issue, I discovered a 3/4 volt drain when ignition is off, and I haven't the faintest clue why.

 

[LLC5]

Just to update the low battery issue, I discovered a 3/4 volt drain when ignition is off, and I haven't the faintest clue why.

A 3-4V drain is not the correct way to check for a battery drain, you need to be testing with an ammeter for a parasitic drain, anything over 50 ma should be investigated. Vetthead Mikey is correct, the gauge reading does sound normal but you should verify with the vehicle running with a known good voltmeter on the battery terminals. You might just have a bad battery, have it properly load tested to make sure it is good.

 

[stevolwevol]

A 3-4V drain is not the correct way to check for a battery drain, you need to be testing with an ammeter for a parasitic drain, anything over 50 ma should be investigated. Vetthead Mikey is correct, the gauge reading does sound normal but you should verify with the vehicle running with a known good voltmeter on the battery terminals. You might just have a bad battery, have it properly load tested to make sure it is good.

I need to correct what I wrote: I have a 3/4 amp drain, not volt.

 

[LLC5]

I need to correct what I wrote: I have a 3/4 amp drain, not volt.

That's a little high. With an ammeter installed in series with the negative battery cable, start pulling fuses one at a time and see if any of the fuses get rid of the drain. If one does you will know the circuit of the drain, and one by one disconnect that circuits components until you find the cause. Aftermarket stereos and alarms are big culprits if you have any installed, in fact any aftermarket electronics would be the first thing to inspect. Good luck with it.

 

[stevolwevol]

Thank you both for your input. I'll get back to this thread when I find the gremlin.

 

[stevolwevol]

One more question. I suspect the alarm that goes to the keyhole on the side of the front fender could be the culprit. Is it ok to disconnect it? If it is, how do I disconnect this?

 

[GTR1999]

Also check the light in the rear compartment. Sometimes they don't switch off when the door is closed and will drain the battery.

 

[stevolwevol]

Also check the light in the rear compartment. Sometimes they don't switch off when the door is closed and will drain the battery.

I don't believe I have a light in the rear compartment. If I do I'd like to know where it's located.

 

[GTR1999]

I don't believe I have a light in the rear compartment. If I do I'd like to know where it's located.

I believe you should have one in the center compartment.

 

[stevolwevol]

I believe you should have one in the center compartment.

I looked, and looked, for the life of me I can't find a lamp anywhere in the back. Could it be that you are thinking of a different year? The 77 doesn't have a fast back. It was the last year of the perpendicular rear window.

 

[GTR1999]

Guess you're right. shows for 68-76

https://www.paragoncorvette.com/p-355679-rear-glove-box-lamp-switch.aspx