Alternator light on, sometimes
 

2001 Escape, 3.0 v6. Almost 80k miles.

The alternator light is sometimes on, sometimes off. Been this way a few years.

Just tested things with multimeter. Car off, battery showing 12.69 v. Start the car, 14.14 v (alternator light off). Then, still running but light on, 14.04 v. So, seems to be charging ok overall. What would cause periodic drop in voltage/light coming on?

Thanks

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Pinpoint-B shown above. Pinpoint-ALL.pdf attached below.

It's good that you know you need to test with a voltmeter at your battery terminals but you only tested it for a split seconds, you need to test (monitor) it while driving continuously with history support and you need battery monitor like this: or . You can buy the exact same thing on aliexpress for half the price than amazon. BM300 you only get very slightly longer bluetooth range and find my car support. This little device is a must have for any cars on the planet, you can view your battery realtime SOC and voltage and you hook this up onto all of your non-daily cars. If you plan to hook this up onto a European car and the battery is in the trunk, or if there is a dedicated jump start terminal in your engine compartment, you hook this up there instead of your battery terminals, so that BM2 doesn't interfere and confuse your BMS.

1) Say one of your non-daily cars, never allow your battery voltage to drop below 12.2V (at rest) or SOC below 50%. When you see 12.2V or 50% DoD on your BM2 app that's the signal to alert you to connect your noco genius 10 to charge it. When you take good care of your car battery this way, a lifespan of 10 years is not uncommon. And expect the lifespan to be 1 to 3 years when you don't feed your battery (by driving or noco or solar).

2) I mentioned split seconds when you tested it with your voltmeter. When you monitor the voltage on your phone's screen, say it's at 14.2V and there is a quick drop to 12.6V for a duration of 1 second during driving, you can see that on your phone or even if you miss it you can still see the history of the voltage and catch the 12.6V drop.
And why should there be a voltage drop like this, too many possibilities, could be bad alternator itself, or voltage regulator, or just the brushes, a wiring problem, or serpentine belt. And when is a big problem with your alternator, you don't get just the red light, you can get light shows with random errors showing up on your cluster, especially on ABS or traction control related.