BQ40Z50-R2: Current and RunTimeToEmpty

Zhihan Zhang

Part Number: BQ40Z50-R2

Hi TI Team,

I found that sometimes "Current" and "RunTimeToEmpty" are not updated at the same time. For example, when negative current appears, at that time, run time to empty is still 65535. This cause some confusing on our customer's host because when battery start to provide power to the host, at the beginning, remaining time in the host may show crazy large time (e.g. 1092 hours) because remaining time is read from run time to empty which is still 65535 at the moment. Can you please advise why there is such inconsistency between Current and RunTimeToEmpty?

Also attach the log data. Please kindly review on highlighted columns and row which point out the issue I mentioned above.

VCPlog1-set1s.xlsx

VCPlog2-set2s.xlsx

Thanks,

Zhihan

over 4 years ago

0 Wyatt Keller over 4 years ago

TI__Guru** 105870 points

Hello Zhihan,

Can you share the .gg file used? It looks like your state time keeps getting reset, so I'm wondering if some of the thresholds were modified to cause the gauge to reset the time.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Please kindly review attached and advise.

Thanks,

Zhihan

597.gg.csv

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105870 points

Hello Zhihan,

The thresholds look fine, I think this is normal behavior since the time calculation may be based on the averages which don't change immediately. The host may just need a delay to read the value so it reports the accurate value.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Thanks for reviewing!

I was thinking that RunTimeToEmpty is based on Current while AverageTimeToEmpty is based on AverageCurrent. So I assume ideally, when current or average current is updated, run time to empty or average time to empty should update accordingly.

While there is a delay you mentioned. So the delay is that updating run time to empty or average time to empty needs additional time after current and average current is updated? Please correct me if I misunderstand.

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105870 points

Hello Zhihan,

That's correct, each one corresponds to a different Current register for calculations. I would still recommend taking the next value after the current starts a discharge to bypass this.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Thank you for you clarify!

Do you know how long roughly is the delay? No need to be precise just maybe typical value for reference only? So that we can have some reference for potential host modification if bypass is not possible.

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105870 points

Hello Zhihan,

The value should be updated after 2 seconds. I will need to check to verify.

Sincerely,

Wyatt Keller

Power management

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BQ40Z50-R2: Current and RunTimeToEmpty