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solarsean avatar image
solarsean asked

Lowering Charge Efficiency for Aging Batteries

Is there any rules of thumb as to how much to lower the charge efficiency factor when your batteries start to show signs of aging/degradation? The BMV has been reading incorrectly when the SOC nears a full charge, and I heard we need to lower the efficiency factor to get it dialed back in.

If it's currently at 96%, do we want to just decrease it in increments of 10%? That would be starting at 86% and then moving from there. Any input people have from managing this setting on older batteries would be great.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

Hi Sean,

You could look in the history of the BMV and get a rough guide from the discharged energy / charged energy.

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karlmr answered ·

I'm also keen to know what the best way is to treat older batteries showings signs of reduced capacity. Is it just by reducing the charge efficiency or should I be adjusting the rated capacity down?

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JohnC avatar image JohnC ♦ commented ·

If it's really reduced capacity, then change that. True loss of charge efficiency would normally express itself as heat, if not just boiling off electrolyte.

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karlmr avatar image karlmr JohnC ♦ commented ·

In my case it's AGM batteries... Limited spike in temperature, so will just reduce Ah.

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