BQ40Z60: Fast Qmax Update without relaxation

Hendra Kusdarwanto

Part Number: BQ40Z60
Other Parts Discussed in Thread: BQ27Z561-R2

In my application, the battery will be always cycled without relaxation so I enabled Fast Qmax Update (FAST_QMAX_FLD=1) to get Qmax update without relaxation. In my testing, I cycled the battery many times but the Cells Qmax only occur twice

For additional information, I use BQ40z60 and I cycled the battery from 5% RSOC until it got VCT. I thought the Qmax will be updated every cycle but in fact, Qmax was only updated twice from 7 cycles, is it normal behavior?

Thanks

over 3 years ago

0 Wyatt Keller over 3 years ago

TI__Guru** 102455 points

Hello Hendra,

The gauge will need to take at least one OCV even with fast Qmax enabled, that is probably why you are not getting updates very often. You should let an OCV reading take place at the end of charge then Qmax should update at the end of discharge.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto over 3 years ago in reply to Wyatt Keller

Prodigy 210 points

Hi Wyatt,

Thanks for your responses. I was looking into one of the Application Report that explains Fast Qmax Update, the test shows that the Q max is updated almost every cycle without relaxation after the end of charge

I know that the above test used BQ27Z561-R2, not BQ40z60. Does the Fast Qmax behavior of BQ27Z561-R2 is different from BQ40Z60?

In my application, I use 4 cells and I wouldn't like to let the battery into the relaxation mode after charge, please let me know if you know another gauge instead of BQ40z60 which suitable for my application

Thanks

- Hendra

0 Wyatt Keller over 3 years ago in reply to Hendra Kusdarwanto

TI__Guru** 102455 points

Hello Hendra,

Can you share your .gg and log file from the test? I'd like to take a look at some of the configurations that may change when the gauge takes an OCV.

What chem ID is being used for your application?

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto over 3 years ago in reply to Wyatt Keller

Prodigy 210 points

Hi Wyatt,

Please check it

battery001.gg.csv

Autocycle 1 (FQmax Enable 5-vct).xlsx

For additional information, In my cycle, I only turn on/off the charger while the load was always connected, the load current is -1000mA. The ID chem = 0x2144

Thanks

- Hendra

0 Wyatt Keller over 3 years ago in reply to Hendra Kusdarwanto

TI__Guru** 102455 points

Hello Hendra,

You will still need to get one valid OCV, make sure all the conditions are met to meet this criteria for your application.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto over 3 years ago in reply to Wyatt Keller

Prodigy 210 points

Hi Wyatt,

OK, thanks a lot, so all of TI BMS controller products will always need one OCV reading to get Fast Qmax Update works?

- Hendra

0 Wyatt Keller over 3 years ago in reply to Hendra Kusdarwanto

TI__Guru** 102455 points

Hello Hendra,

That's correct, it will need at least one valid OCV measurement for fast Qmax.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto over 3 years ago in reply to Wyatt Keller

Prodigy 210 points

Hi Wyatt,

Ok got it, thanks a lot

- Hendra

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BQ40Z60: Fast Qmax Update without relaxation