Correct running volts?

[highwaystar]

Volt reading with radio on, parking lights on, ac on medium. Looks ok??

 

[smdk2500]

I wouldn't trust the gauge. My 95 will show that then I can lightly tap the dash and it will raise or lower. To be sure put a voltmeter or scan tool on to double check. Should read anywhere between 13.5v-14.5v if I remember correctly.

 

[Schurkey]

Thousands and thousands of years ago, when vehicles had voltage regulators that could actually be adjusted, we were trained to set them between 13.5 and 15.5, with the higher voltage in the winter.

Now I expect to see something in the 14-ish volt range--14.2--14.7--at the alternator output terminal. Due to voltage drop, somewhat less farther away from the alternator.

The dash gauge on my '88 is dreadfully inaccurate, and nearly always reads low.

 

[GoToGuy]

The truth is at the alternator output and the battery.

 

[GoToGuy]

DC volts drops over distance, by using larger diameter wire can reduce the drop, but not eliminate it.
AC drives long distance.
Edison lost.

 

[Komet]

Looks fine to me, you could double check with a voltmeter on the battery when it's running.

 

[highwaystar]

Thanks. It reads 14V running with all accessories off.

 

[Schurkey]

It reads 14V running with all accessories off.

Where? At the dash gauge? Or at the alternator output?

"I" would want to know what voltage is at 2000 engine rpm, and with every electrical load in sight turned on--bright headlights, AC compressor, radio, turn signals, HVAC fan, and anything else you can think of.

 

[L31MaxExpress]

Remember that GM voltage regulators have been temperature compensated for decades. When you first start the vehicle, you will see 14+ volts. As the engine, engine compartment and alternator heat up it is completely normal to see the voltage drop down to as low as 13.2ish and after hours on the road, I have seen them output as little as 12.8V and still be functioning within design specification. Remember after all a fully charged battery is like 12.6 volts and charging at a high voltage for a long period of time can cook the electrolyte right out of the battery.

This was my 97 van tonight after it was well heat soaked and had run for more than 30 minutes. Weirdly my OE voltmeter is right on the money with what my DMV shows at the battery.

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[highwaystar]

So, I was having intermittent starting issues. Threw parts at it: battery, starter, battery cables, still no joy. Just a click at the starter several times then it would crank. Just put a new alternator on and the volts now don't go below 14 and no more cranking issues, knock on wood. Alternator was about 12 years old with a lifetime so I swapped it at the parts store, new belt too. So what is the minimum voltage the truck wants in order to crank? And what part is seeing this? The ecm I guess?