BMV-712, Battery Monitor

Hi Everyone,

I have a site with 2 battery banks, and I have 2 units of BMV-712 (one per each).

However, the BMVs have been calibrated when the batteries were full, but I found out later that the BMV readings are different from the real SOC

E.g. the SOC was 80% on BMV, however, on it was 20% on the batteries themselves.

What should have made this critical difference? Why the BMV is not giving the correct state of charge?

The batteries are Li-ion and each bank has 15 units of 100Ah).

Kindly advise.

2 |3000

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Matthias Lange - DE ♦ commented · Jan 06 at 01:33 PM

Please give us some more details.

What batteries do you have exactly? How is everything wired? What are the settings of the BMV?

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tareq Matthias Lange - DE ♦ commented · Jan 06 at 02:10 PM

Dear Mathias,

The images below show how are the batteries connected to client cabin and the BMV settings.

The batteries are Huawei.

We have 30 batteries in total.

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screenshot-20240106-170837.jpg (331.1 KiB)

screenshot-20240106-170627-samsung-notes.jpg (114.7 KiB)

Matthias Lange - DE ♦ tareq commented · Jan 06 at 07:25 PM

To be honest I don't understand that drawing. Where are the loads connected?

All batteries need to be connected to the battery side of the shunt.
In you drawing there are 10 batteries on one side and 5 on the other side of the shunt.

At last the Peukert exponent is wrong, for lithium it should be 1.05.
The charged volteage seems a bit high.

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