Bugly87

hello
1987 Vette Auto 49,000 miles recent purchase

The previous owner never drove it. Got the fuel filter replaced, fresh gas, cleaned TB, etc now it runs fine. I was driving the other day and noticed that at 2000 rpm my volt meter only read 13.3. On the way home it was 13.3 also.. It was raining so wipers on defrost on and headlights on...volts down to low 12's actually went to 11.8 at a stop. I got home and with the car running and everything off it read 13.3. I searched and it seems as though I may be boarderline but I am pretty sure it should charge at high 13 or low to mid 14 volts. The alternator is probably original so I will replace it. What voltage should the battery be charging at? I also have a voltage draw that I am tracking down but thats a later issue.

Thanks for any direction

Kevin

jfb

Alternator cold, the dash voltmeter should read 14.3 volts and the alternator output voltage drops with increasing temperature and at its operating temp, the dash voltmeter will read 13.3 volts. This is normal. With a high current draw, the alternator cannot generate its rated current at idle rpm and you can expect the dash voltmeter to drop until you get underway. But with the load you describe, I would expect the alternator to keep up even at idle and maintain 13.3 volts.

navy_vette

Start her up and check the actual voltage at the battery with a voltmeter. It's a common thing to loose about .5 volts on it's way to the cluster. Compare it to the gauge and you'll know how much it's off.

The voltages sound about right though. Don't worry about it.

Congrats on the new car!

Let's see some pics!

Bugly87

Thanks for the quick replies. I did check the voltage at the battery and did see about a .5 difference at the battery as compared to the dash. The battery being higher. I became concerned driving home and seeing the volt meter dip below 12 volts for a sec. I do have a draw at the battery also. With the engine off the battery read 12.34 volts. It slowly began losing voltage to the tune of about .25 volts in a half hour. It began to rain so I stopped the check. The battery is new and discharges in 3 days. What is the best way to check for this draw...to pull the fuses one at a time to see if the draw stops, or is there a better, easier, and more accurate way to check? I will post pics soon. It is my third Vette..Having a 84 and a 80 earlier,

Thanks again
Kevin

navy_vette

Parasidic battery draw is a common problem with all older cars. It could be something as simple as the center console gravity switch not turning off, or as bad as a short in the wiring harness. As an Electronics Tech, I say pulling fuses to hunt for a draw is a bad idea. As a C4 owner, I say it's a good option...

First, make sure that when you shut the car off and close the doors, every single light, gauge, display and every single other minor detail of the interior turns off. Double check things you don't normally see, like the center console lid light, under-hood lights (both of which run on gravity switches) and the visor lights.

RWDsmoke

I have a clamp on meter that has a DC amps setting. I found an automatic circuit breaker for the power seat circuit that was shorted. It would trip then reset several minutes later. It would discharge the battery in two days if I didn't drive the car. I Would still be looking if I didn't use that meter.