BQ40Z80: Ra table GPCRB scale

xiulan zhao

Part Number: BQ40Z80
Other Parts Discussed in Thread: GPCRB, GPCCHEM

Hi all,

We used BQ40Z80 Impedance Track Gas Gauge. We do GPCRB optimization through Arbin battery testers. So the measured resistance is the real cell resistance. However, in the fuel gauge we scaled down the current by a factor of three. At this time, is the resistance in GPC-report the real internal resistance? Or scaled?

In addition, if we actually measure the cell resistance, to fix the resistance in the gg file, do we need to triple the internal resistance?

If the Ra table does not need scaling, but the current recorded by the fuel gauge is scaled, how to match the Ra table?

Sincerely,

Xiulan

over 3 years ago

0 Wyatt Keller over 3 years ago

TI__Guru** 105590 points

Hello Xiulan,

The cell resistance should not be modified after the learning cycle has completed for the gauge. The Ra table the gauge learns is specific for the whole system it is in. You should never manually change the Ra values after learning, this will cause errors in gauging.

Sincerely,

Wyatt Keller

0 xiulan zhao over 3 years ago in reply to Wyatt Keller

Prodigy 160 points

Hello Wyatt Keller,

I know what you mean.We are doing GPCRB learning. For the fuel gauge with current scaling, when GPCRB learning is performed, if the Abin device is used for testing, does the final submitted current need to be scaled and then submitted? which is very important for us to solve the problem.

Sincerely,

Xiulan

0 Wyatt Keller over 3 years ago in reply to xiulan zhao

TI__Guru** 105590 points

Hello Xiulan,

If you are using current scaling you should be implementing it in this method: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1026728/bq40z80-current-scaling-bug-workaround-instructions

The data you submit to the GPCRB tool should also be scaled, nothing else should be scaled in the gauge. Once you scale the current values in the gauge all the learned Ra tables should not be changed since it was learned while scaled.

Sincerely,

Wyatt Keller

0 xiulan zhao over 3 years ago in reply to Wyatt Keller

Prodigy 160 points

Hello Wyatt Keller,

If we triple the capacity in the gg file, the current value we measure with the Arbin test equipment should also be tripled before submitting to TI's GPCRB learning site.Does this understand correctly?

Sincerely,

Xiulan

+1 Wyatt Keller over 3 years ago in reply to xiulan zhao

TI__Guru** 105590 points

Hello Xiulan,

Yes everything should be consistent for the gauge configuration to the data submitted to the tools. This is because we use the current to help calculate the internal resistance and OCV of the battery so when we watch the chem ID with GPCCHEM or do an Rb tweak, everything is using the same adjustment factor.

Sincerely,

Wyatt Keller

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BQ40Z80: Ra table GPCRB scale