What is normal voltmeter reading?
Thread Starter
Racer
Joined: Apr 2002
Posts: 353
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From: Tuscaloosa AL
What is normal voltmeter reading?
My voltmeter reads 13.9-14.0when it first starts ('88 with a whole bunch of upgrades including MSD)then as the motor warms it creeps down and usually ends up fluctuating between 13.2-13.5 volts. This is with the radio and the headlights off. Is this normal? My alternator and battery are new (140 amp alt.).
Also, I had it up on jack stands for about 2 months putting in new suspension and brakes, and I forgot to disconnect the battery. I had the drivers door open alot when I was doing the brakes. When I went to start it the first time, the battery went dead while it was cranking. Could interior lights drain the battery that much?
Is there any simple way to find out if I have some kind of abnormal battery drain? thanks for the help fellas
Also, I had it up on jack stands for about 2 months putting in new suspension and brakes, and I forgot to disconnect the battery. I had the drivers door open alot when I was doing the brakes. When I went to start it the first time, the battery went dead while it was cranking. Could interior lights drain the battery that much?
Is there any simple way to find out if I have some kind of abnormal battery drain? thanks for the help fellas
Pro
Joined: Jun 2001
Posts: 509
Likes: 5
From: Edmonds WA
Sounds like you are dealing with a very similar problem to mine. See this thread: http://forums.corvetteforum.com/showthread.php?t=884013
And, yes, if your battery is on its last legs, interior lights can drain it down. Also, the ECM draws a slow drain... it killed my battery (deader 'n a doornail) last year when it was on stands for a couple of months for repairs. It's been running OK since, but now I'm having problems which might be battery related. Good luck!
And, yes, if your battery is on its last legs, interior lights can drain it down. Also, the ECM draws a slow drain... it killed my battery (deader 'n a doornail) last year when it was on stands for a couple of months for repairs. It's been running OK since, but now I'm having problems which might be battery related. Good luck!
Team Owner
Joined: Sep 2001
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From: Athens AL
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Interior lights do drain the battery.
I think your voltage readings are within spec, nothing really to worry about until the voltage drops into the 12s.
But you can NEVER trust a GM voltmeter, you need to check it with an external meter. Mine reads what yours does in the dash, but an external meter shows its off by 0.6V.
I think your voltage readings are within spec, nothing really to worry about until the voltage drops into the 12s.
But you can NEVER trust a GM voltmeter, you need to check it with an external meter. Mine reads what yours does in the dash, but an external meter shows its off by 0.6V.
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Joined: Jul 2003
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[QUOTE=Also, I had it up on jack stands for about 2 months putting in new suspension and brakes, and I forgot to disconnect the battery. I had the drivers door open alot when I was doing the brakes. When I went to start it the first time, the battery went dead while it was cranking. Could interior lights drain the battery that much?
Is there any simple way to find out if I have some kind of abnormal battery drain? thanks for the help fellas[/QUOTE]
If it turned over at all after two months with the int. lights on at times, your battery is fine and you have no unusual drains.
Is there any simple way to find out if I have some kind of abnormal battery drain? thanks for the help fellas
[/QUOTE]If it turned over at all after two months with the int. lights on at times, your battery is fine and you have no unusual drains.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Your electrical system is normal. Cold, the alternator puts out 14.7 volts and because of the 0.3 volts drop across the ignition switch contacts, the dash voltmeter will read 14.3 volts. As the alternator gets warm its output drops 1 volt to 13.7 volts and the dash will read 13.3. Car batteries lose 1% of their charge each day, so with the doors open and sitting for 2 months, you should consider yourself very lucky that the starter cranked at all. Always periodically charge your battery when it won't be used for long periods (4+wks) because as the battery discharges the plates collect lead sulphate and lead sulphate is a good insulator. Fully sulphated, you have a door stop. If you have a battery charger, buy an interval timer (turns your lights on when you aren't home) and have it charge your battery each day for its minimum interval (usually 15 mins). You can tell the state of charge in your battery by measuring the battery terminal volts under no load (underhood lights are ok). 12.0 volts or lower, discharged. 12.9 volts or higher, fully charged. ALWAYS use a battery charger to charge your battery up, NEVER use the alternator!
