BQ40Z50-R1: bq40z50-R1 capacity problem

Annie Liu

Genius 10295 points

Part Number: BQ40Z50-R1

Hi Team,

The capacity update is 1942mAh, as shown below.

But the actual charge is only 1848mAh

over 6 years ago

0 Batt over 6 years ago

TI__Mastermind 42535 points

Hi Annie,

That's OK. Qmax is unloaded capacity. For new cells it can be higher than design capacity. FCC is calculated with load, so it accounts for IR drop and therefore FCC will always be lower than Qmax.

0 Annie Liu over 6 years ago in reply to Batt

TI__Genius 10295 points

Hi Batt,

Thanks for your answer. In other words, after several charge and discharge cycles, will the FCC slowly approach Qmax?

0 Batt over 6 years ago in reply to Annie Liu

TI__Mastermind 42535 points

Hi Annie,

Actually, if your load is light, your FCC will be closer to Qmax.

0 Annie Liu over 6 years ago in reply to Batt

TI__Genius 10295 points

Hi Batt,

Sorry, there is following question. The relative capacity is quite different from the absolute capacity. After full charge, the relative capacity is 100% and absolute capacity shows about 95%. May I know what is the reason?

Thanks.

Annie

0 Batt over 6 years ago in reply to Annie Liu

TI__Mastermind 42535 points

RSOC = RM/FCC, ASOC = RM/Design capacity. As the battery ages, ASOC will get lower because cell resistance increases with age related degradation.

0 Annie Liu over 6 years ago in reply to Batt

TI__Genius 10295 points

Hi Batt,

Whether to turn on the FAST_QMAX_FLD bit while learning？
Does customer need to close after learning success?

0 Batt over 6 years ago in reply to Annie Liu

TI__Mastermind 42535 points

No, it can be set. It will not affect gauging when pack is not learned. It will only calculate fast Qmax once the pack is learned. That is why you have 2 bits FLD and LRN.

0 Annie Liu over 6 years ago in reply to Batt

TI__Genius 10295 points

In other words, once customer has learned PACK, FAST_QMAX_FLD should be opened. Is that right?

0 Batt over 6 years ago in reply to Annie Liu

TI__Mastermind 42535 points

Yes, that is correct.

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BQ40Z50-R1: bq40z50-R1 capacity problem