Ve.BUS SOC for BYD system

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gregn asked Dec 3, '18

Ve.BUS SOC for BYD system

Hello

We have a big 20 kWh BYD battery with 3 Quattros and 4 MPPT's.

I know the issues and problems with te SOC values of the BYD system (50W limit per module).

So as bigger the system is , so bigger the problem gets.

We get the inaccurate current reading problem and it is not nice for the customer to read a sudden SOC drop...

Instead of installing a BMV and having other problems...does anyone has experienced the SOC reading from Ve.bus with the "Use solar charger current to improve VE.Bus SOC " function on? I did it with Victron Lithium and it works good, but with BYD I ask myself?

It works so far not bad.

Thank you for a feedback.

BYD

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Answer 1 · 2018-12-03T08:19:24Z

Guy Stewart (Victron Community Manager) answered · Dec 03, 2018 at 08:19 AM

If you did wish to go this alternative (which has it's own problems too), you will also need to modify which battery monitor gets priority in the system:

The good think about this option is that it is easy to change back and forth, if you find the limitations of one is more desirable than the limitation of the other.

Report back if you learn something!

screen-shot-2018-12-03-at-71544-pm.jpg (113.7 KiB)

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Answer 2 · 2018-12-03T08:33:09Z

gregn answered · Dec 03, 2018 at 08:33 AM

Yes. Ok this is was I did. I follow the system to observe if the SoC % drift is better.

What other problems did you mean by "which has it's own problems too "?

p.e. Zero Power consumption of Ve.Bus (Multi's...) reading error?

I'll come back to report.

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Guy Stewart (Victron Community Manager) ♦♦ commented · Dec 03, 2018 at 10:58 AM

The CT of the Multi is not perfectly accurate either :)

Also if one of the battery modules drops out, you will not get a dynamic update of the available SOC like you would using the built in BMU. The VE.Bus BMS uses a programmed and static battery capacity. BYD BMU has a bit more info to work with from its BYD BMS batteries.

We hope a long term fix comes from BYD and they improve the minimum current reading of their batteries. That is really the best solution to use the native SOC.

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