question

yagu avatar image

Battery voltage limit

We have a couple of Multiplus v2 5k, a 5k AC coupled Fronius, 4 BYD b-box LV 48v batteries and a Cerbo to tie it all together.

Now I want to limit the charging voltage on the BYD batteries from 58.4 volt to 56.4 volt. According to Will Prowse this will greatly increase battery lifetime. Please correct me if I'm wrong.

I have no idea how to do this. In Venus OS, the CVL option under the BYD parameters is not changeable. Do I need to do this in the BYD software somehow?

Thanks in advance,

Joris

Multiplus-IIoffgridFroniusBYD
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·
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yagu avatar image
yagu answered ·

From that documentation I take away:

Such intelligent BMS sends the following parameters to the GX device:

  1. Charge voltage limit (CVL): the maximum charge voltage that the battery currently accepts.

  2. Charge current limit (CCL): the maximum charge current requested by the battery.

  3. Discharge current limit (DCL): the maximum discharge current as requested by the battery.

For all three parameters, some types of batteries transmit dynamic values. For example they determine the maximum charge voltage based on cell voltages, state of charge, or for example temperature. Other makes and brands use a fixed value.

It is still very confusing.
I take away from this that the CVL and other parameters are supplied by the batteries BMS. Would it be more logical to change that in the BMS settings instead of overriding it in Venus? I couldn't even make out if I can even change it in Venus.

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