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Old 01-09-2012, 11:51 AM   #36 (permalink)
MetroMPG
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What does the "peak detection" setting mean on the Super Brain?

Before starting this project, I had done little to no reading about NiMH batteries, so I was puzzled by the "peak detection" parameter needed for setting up a charge cycle.

I'm posting this for others who may find themselves in the same boat.

It boils down to the way NiMH batteries behave as they reach a full charge: their voltage peaks and then declines slightly. Until that happens the charger says, "nope! Not full yet," and keeps on going. (This behaviour is more obvious at higher charging currents, such as the ones being used to cycle the Insight sticks.)

You can see it in the NiMH charge profile, from Wiki:



source: Nickel

So with the Super Brain setting at "5 mV per cell peak detection" for charging the 6 cell subpack, it waits until it detects a voltage drop of 30 millivolts or more (30 = 6 cells times 5 mV) from the highest peak seen so far before concluding the charge cycle.

You can sometimes see this if you watch the voltage display near the end of the charge cycle. It will rise slowly & steadily up to, say, 9.14 Volts, then flicker back and forth to 9.13 V a little bit before ending the cycle.

I'm learning... I'm learning...
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