question

nickdb avatar image
nickdb asked

multiplus stuck on float (again)

Having sorted SOC reporting (mostly) my ESS setup that reliably kicks into bulk/absorb overnight after battery usage, now will not do so.

Temperatures have increased from the mid 20's to lower 30's and I use DVCC.

My float is set to 54.4V.

Originally I thought that temps had improved the batteries storing of charge, so I increased the overnight discharge level to try force a bulk cycle.

Battery voltage hit 48.8V which is more than 5V below float, so it should change to bulk but it doesn't.

Is temperature compensation lowering the float voltage and the system needs to be 5V below this?

Any suggestions for what to do about this.

I have multiple multis in a similar config behaving the same.

Multiplus-IIbattery chargingESSfloat
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1 Answer
Mark avatar image
Mark answered ·

Yes the re-bulk threshold voltage is also compensated by temperature.

If you know what the reported battery temperature is at the time, the configured temperature compensation coefficient and the configured float voltage - then you can manually calculate the resultant voltage threshold quite easily.

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nickdb avatar image nickdb ♦♦ commented ·

Hi @Mark, I had presumed as much. The question is what can I do about it?

Must I just live with it until it cools down or should I increase my float voltage (it's on the lower end of the battery specs)?

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Mark avatar image Mark ♦♦ nickdb ♦♦ commented ·

Hi Nick, yes unfortunately as the re-bulk voltage offset is not configurable and because its temperature compensated, there is not too much you can do about it...

Some potential work arounds:

  • Try to set the 'repeated adsorption' interval to every day and see if that helps
  • Increase float voltage a little if its on the low end of the battery manufacturers recommended specs
  • Check and potentially decrease the temperature compensation coefficient
  • Simply drain the batteries down a little lower each day
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