BQ27220: Pulsed discharge current / Accuracy of capacity measurement

Daniel Gianfreda

Part Number: BQ27220
Other Parts Discussed in Thread: BQSTUDIO

Hi,

We testing the fuel gauge with a discharge current: 20mA for 20ms repeated every 1 second for 40 hours.

The fuel gauge is set up using the scaling factor (according application) x10 and using as shunt resistor 100mOhm.

Theoretically it will consume 16mAh with this current profile. The fuel gauge is measuring a difference of capacity of 11.6mAh (RemCap) and 15.5mAh (True RemCap)

Which values of RemCap is recommended to use? And are there some recommended parameters to optimize in the fuel gauge for low current application?

Daniel

over 6 years ago

0 Onyx Ahiakwo over 6 years ago

TI__Guru* 76230 points

Hi Daniel.

The true rem cap is a more accurate representation of the remaining capacity and should be what you use.
Have you seen this app note:
www.ti.com/.../slua792

though written for a different device is applicable to this.
thanks
Onyx

0 Daniel Gianfreda over 6 years ago in reply to Onyx Ahiakwo

Prodigy 140 points

Hi Onyx,

thanks for your feedback.

Another question is, shall we keep the deadband parameter to 5 mA or shall it be set to 0 mA. Has the deadband any influence on the capacity calculations?

best regards,

Daniel

0 Onyx Ahiakwo over 6 years ago in reply to Daniel Gianfreda

TI__Guru* 76230 points

Deadband has no influence on capacity calculations. It is only use by bqstudio
thanks
Onyx

0 Daniel Gianfreda over 6 years ago in reply to Onyx Ahiakwo

Prodigy 140 points

Ok. Understood.

Thanks and BR

Daniel

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BQ27220: Pulsed discharge current / Accuracy of capacity measurement