I had a question about my Voltmeter. It was explained to me 2 different ways on how the voltmeter works. First, is basically displays the battery's current voltage. Two, it display the current charge/amount being charged back to the battery. The first one sounds correct. Either way the issue is when i first start my '88 IROC LB9 the voltmeter read about 15-16volts. After it operates at normal operating temperature for about an hour it'll go down to about 12-14 Volts. These are ranges it usually falls somewhere in between but I've seen go as far as listed above. I'm concerned that either I just don't understand what exactly is happening in that circuit or maybe my voltage regulator isn't controlling the charge back to the battery properly? Any suggestions would be appreciated.

 

When cold, the engine idles at a higher rpm, thus alternator is charging slightly higher amounts, thus the difference.

Voltmeter measures voltage being supplied by alternator to the battery, not the battery voltage. You'll see the voltmeter raise slightly during accelleration - higher rpms = faster turning alternator = more charging of battery.

 

Right, I'm following you there. My concern is that the voltmeter is staying high a little too long after the engine is already warm. At this point I've been driving around for about 30-45mins on a warm engine. I'm thinking that maybe the internal voltage regulator isn't adjusting the voltage back down after the alternator charges the battery after startup. What do you guys think? Is there anyway to test the output voltage to the battery, or just measure the voltage at the battery when i see this?

 

Run to advance, autozone, oreilly, whatever - they all test alternators for free in the car.

 

Thanks, i'll have to do that. I appreciate the help.