BQ27520-G4: RM value shifts due to long-term storage

SUZUKI YASUO

Part Number: BQ27520-G4
Other Parts Discussed in Thread: GPCRA0, GPCRB

When the battery is connected and stored for a long time with the power off, the battery becomes empty due to the standby current, but the RM value is close to a fully charged value. What is the cause?

If the discharge current is high to some extent, the RM value will not deviate, but if the discharge current is small, will the RM value deviate?

over 1 year ago

0 Shirish over 1 year ago

TI__Guru 57747 points

Hello

It is likely to be a configuration issue that the gauge is not detecting standby current.

Does the "Initial Standby" current match the system standby current? Is the deadband set below the standby current?

For more information see TRM 2.13 StandbyCurrent( ): 0x18 and 0x19

0 SUZUKI YASUO over 1 year ago in reply to Shirish

Prodigy 20 points

Hello

"Initial Standby" is set to -10mA, and "Deadband" is set to 5mA.
The actual standby current will be 0.6mA.

Will there be any deviation in this case?

Also, will the deviation increase if stored in a low temperature environment?

0 Shirish over 1 year ago in reply to SUZUKI YASUO

TI__Guru 57747 points

One option would be to reduce deadband so that standby current is detected but since the standby current is less than 1mA, i don't think that is possible.

The other option is to use the gauge feature of compute capacity at rest Please see TRM section 5.1.7 Quit Current, Dsg Relax Time, Chg Relax Time, and Quit Relax Time

Also please confirm that the correct matching chemistry was programmed to the gauge and learning cycle was completed

0 SUZUKI YASUO over 1 year ago in reply to Shirish

Prodigy 20 points

Thanks

Quit Current is set to 20mA, Dsg Relax Time and Chg Relax Time are set to 60 seconds, so the device is in relaxation mode.

The ChemID settings are correct and the learning cycle is complete.
Does storage in a low temperature environment affect the updating of the Ra table?

0 Shirish over 1 year ago in reply to SUZUKI YASUO

TI__Guru 57747 points

How low is the temperature? For low temperature optimization you can use the GPCRA0 and GPCRB tool.

0 SUZUKI YASUO over 1 year ago in reply to Shirish

Prodigy 20 points

Thanks.
The environment will be about 0 to 10°C.
I will consider GPCRB, which also considers low temperatures.

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BQ27520-G4: RM value shifts due to long-term storage