BQ29209: Cell balance with 15 mA, when it is enough ?

Stefano Sivera

Prodigy 201 points

Part Number: BQ29209

Hi guys,

my application is 2S Li_ion battery 3,7V 700mA with charging current CC/CV at 100 mA.( 8 h for complete charge).

In my previous test the imbalance voltage (without BQ29209) is around 250/300mV at the end of charge.

The draw current of 15 mA, managed by internal MOS of BQ29209 can be enough for correct balance ?

Thank you

Best Regards

Stefano Sivera

over 2 years ago

0 Matt Sunna over 2 years ago

TI__Guru* 80213 points

Hi Stefano,

This should be plenty based on your application description.

Best regards,

Matt

0 Stefano Sivera over 2 years ago in reply to Matt Sunna

Prodigy 201 points

Hi Matt, thank you for answer.

When is suggested increase the draw current ? I suppose at higher charge current but there is percentage value of charge current ?

Thank you

Best Regards

Stefano

0 Matt Sunna over 2 years ago in reply to Stefano Sivera

TI__Guru* 80213 points

Hi Stefano,

This depends on multiple factors, there is no simple rule. For higher capacity cells it will take longer to balance. If you know the voltage/capacity curve of your battery cells, you can calculate how long it will take to balance a certain amount of voltage difference. Since your charge current is low, 15mA is a big percentage of the charging current, so it should be able to balance cells effectively.

Regards,

Matt

0 Stefano Sivera over 2 years ago in reply to Matt Sunna

Prodigy 201 points

Hi Matt, thank you for your help.

Best Regards

Stefano

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BQ29209: Cell balance with 15 mA, when it is enough ?