question

leahmarc avatar image
leahmarc asked

Charge efficiency

Hi, I have 4 x 270 Ah AGM batteries in parallel / series giving 24 volt and 540 ah monitored with a BMV 712

I have the discharge floor set to 50%

I set up the relay to activate my generator when the batteries fall to 50% charge

What should my Charge Efficiency be set too ??


BMV Battery Monitor
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Leahmarc

You'll need to determine this yourself based on trial and error. You could start with the default 95%, and if that's too high the SOC will reach 100% before the Tail current prompts a sync. Conversely, if it's too low the sync will happen before the SOC makes it back to 100% naturally.

Efficiency also varies depending on how deeply you discharge the batts. Deep discharge is more efficient to replenish than shallow. I change mine between winter and summer, and Temperature may also have an effect.

As a side note, Peukert needs similar attention for discharge. And I suspect a 50% SOC before you start your genset might be too low.

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