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Smarter than the Averaging Digital Voltmeter

PostPosted: Sun Jun 05, 2016 10:10 pm
by Coulomb
Sometimes people ask why a regulator doesn't achieve a given set point. This question often comes up when attempts at equalization are done and the user has been glued to their digital voltmeter.

A typical digital voltmeter averages internal readings before displaying the average. Averaging may take place over several seconds.

Ample Power regulators measure battery voltage in excess of 4000 readings a second. Each of those readings is used immediately to affect alternator field current.

Changes to set points use a one second average of those 4000+ readings. It's unlikely that a human observer with a typical digital voltmeter will be able to catch the excursion that causes the regulator to switch states, say from equalization back to float.

There are digital meters which will capture peak readings. The Fluke 87 will capture both minimum and maximum peak voltages and hold them until released. This meter can capture the peak voltage of a given set point.