Intermittant Voltage Drop. Battery & Alternator are OK.?

Question

I have a '95 Buick Skylark GS with a 3.1. The alternator is 3 years old and the battery is an 84-month battery by Exide.

When I start-up cold, everything works great and the voltmeter guage goes past 13, almost to 15 volts no matter what load is on like the radio, A/C, rear-window defogger, lights, signals, etc. Occasionally and usually after the car is warmed-up, I'll have a drop in voltage, almost down to 10 volts. It will go up a bit when I rev the engine; it will drop way down when it's under load from the aforementioned electrical items. I've had the battery and alternator both check-out OK.

Thanks for your assistance if you have any ideas about this.

The car hasn't conked-out because if this, but it may....

Answer 1

No, that's normal. When you crank the engine over, you use some of the battery's energy so the alternator tries to replace that energy and you'll see the voltage go up (up to 15 is good, anymore can hurt the battery) After the alternator replaces the energy that was used by cranking, the voltage regulator brings the charging voltage back down to 12 volts or so.

Answer 2

Check the ground wire between the engine and the frame. If it's loose or missing you'll have wild voltage fluctuations.
The alternator and battery are grounded to the engine, but everything else is grounded to the chassis, so you need a good connection between the two.

Answer 3

check the ground wire from the battery to the frame. if it is making a good connection, check the voltage drop when turning the car over. this will tell what the starter draw is, and whether or not you have a short there. if all is good here take your ignition module to your local napa auto parts to have it checked

Answer 4

each and every thing that contributes to rotational mass places extra stress on the battery... eg, No ability guidance and a/c and or no followers ability extra ability. no longer that that's the case. Aslong as your no longer popping fuses and your vehicle starts off no problem you need to be positive.