How to get 0% SOC from BYD Battery-Box L 7.0

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Joan asked Sep 3, '23

How to get 0% SOC from BYD Battery-Box L 7.0

Hello,
System with Quatro, Fronius in ac-coupling, BYD Battery-Box L 7.0 and Venus GX.
We are facing a problem of loss of capacity of the Battery-Box L 7.0
Following instructions from @byd-service EFT-Systems, complete 0% discharge and 100% SOC charge cycles are required.
The scheduled discharge carried out to reach 0% SOC stops between 7 and 5% SOC.
The latest query to EFT-Systems asks that a system configuration be carried out through changes in the voltage parameters to get the batteries to complete the discharge at 0% SOC.
Could any Victron technician or user give me instructions on how I should proceed to completely discharge the 0% SOC battery?
Thank you.

Lithium Battery SOC BYD battery capacity

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2 |3000

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Alexandra ♦ commented · Sep 03, 2023 at 04:45 PM

@Joan

Replying in private here as i dont want to be responsible for fueling crazy ideas in peoples heads.

To get the inverter settings to allow rhe full discharge....

Set all your ESS dynamic cut off voltages to under the low voltage cut off of the Battery (see the manual)

Set the system in the inverter tab to switch off on SOC and set that to 0%.

And set the low cut off voltage as well to the lowest dc voltage on the inverter tab.

If this does not work, you will have to disconnect the inverter from the GX and run it down like that.

This will prevent the battery from shutting the system down. Keep the BYD connected to the GX though otherwise it will shut down anyway.

You will still have the logging but not the battery control.over the inverter. The next shut down will be the battery disconnecting itself.

For this test though have the fronius off. And any other items that are a charge source to prevent damage.

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Answer 1 · 2023-09-03T16:45:52Z

Alexandra answered · Sep 03, 2023 at 04:45 PM

@Joan

Check in the GX if it is the battery sending the 0A DCL to the system when it is shutting down early.

If this is happening at higher than set then it it likely there is a weak cell dropping lower than others and the system is shutting down early. This also can be checked through the VRM.

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2 |3000

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Alexandra ♦ commented · Sep 04, 2023 at 12:59 PM

@Joan

The BYD warranty document has the test procedure for working out battery capacity.

They even include the ambient temperature requirements

So look up the battery module warranty document for the area you live in.

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Joan Alexandra ♦ commented · Sep 04, 2023 at 05:24 PM

Hi @Alexandra

I am grateful for your response with information and technical advice. I understand the procedure I must follow.

Over the next few days, I will carry out the configuration and discharge of the battery.

I will share the result.

All the best.

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