BQ27421-G1: BQ27421-G1A SOH status always 0x00

Wojciech Obrebski

Part Number: BQ27421-G1
Other Parts Discussed in Thread: BQSTUDIO

Hi,
In my device a I have permanently attached battery (nominal 1100mAh, 3.7V) which is charging with maximum 1A current and charging is terminate when current drops below 50mA. Device draws 20mA - 50mA in normal condition and below 100uA when is in standby. It is also in standby when voltage at battery drops below 3100mV.
After power up device checks if ITPOR is 1 and initialize BQ27421-G1A with this values:
Design Capacity = 1100
Design Energy = 4070
Terminate Voltage = 3200
Taper Rate = 192
Sleep Current = 5
Hibernate I = 1
Hibernate V = 2750
Dsg Current Threshold = 733
Chg Current Threshold = 244
Quit Current = 1100

OpConfig[HighByte] = 0x05
then execute command: BAT_INSERT, SET_HIBERNATE, SOFT_RESET.
After few charge/discharge periods i realized that FullChargeCapacity( ) is around 1227mAh and SOC seems to be properly estimated. But SOH Status is always 0x00 (SOH Value is same as SOC).
Is my settings ok?
In SLUUAC5 (June 2013): Dsg Current Threshold, Chg Current Threshold, Quit Current have units [mAh] but in bqStudio (Version : 1.3.86) they are in [0.1 Hr rate]...
Best Regards
Wojtek

over 4 years ago

0 Wyatt Keller over 4 years ago

TI__Guru** 105590 points

Hello,

Can you export your .gg file and log the cycles so we can take a look at your settings?

The units should all be 0.1Hr in the TRM as well as bqStudio, can you share a screen capture or section number where they are defined as mAh?

Sincerely,

Wyatt Keller

0 Wojciech Obrebski over 4 years ago in reply to Wyatt Keller

Intellectual 480 points

Sorry - i can't :(

when the device was designing i I had no knowledge of bqStudio and other tools and that logging is needed so it is no implemented :(

Can you only confirm that initialized values make sense?

0 Wyatt Keller over 4 years ago in reply to Wojciech Obrebski

TI__Guru** 105590 points

Hello,

I'm not sure which document you are reviewing, I checked the TRM and found the section you are looking at but it has 0.1Hr.

TRM: www.ti.com/.../sluuac5c.pdf

Make sure the gauge does a Qmax update during the cycles to see if the SOH updates. You can also try updating the SOH load to match your own load.

Sincerely,

Wyatt Keller

0 Wojciech Obrebski over 4 years ago in reply to Wyatt Keller

Intellectual 480 points

Thank you,

i had older version which i found via google...

SOH Load? What do you mean?

This one: Load Select / Mode (Sybclass Id = 82, Offset = 5) ?

0 Kang Kang over 4 years ago in reply to Wojciech Obrebski

TI__Mastermind 24870 points

Hello Wojiech,

It is called SOH Load I and not the load mode/select.

Thanks!

0 Wojciech Obrebski over 4 years ago in reply to Kang Kang

Intellectual 480 points

Thank you Kang,

In sluuac5c.pdf there is only one place (at paragraph 4.15) where "SOH Load" is used. Where i can find register which i have to set to change SOH Load?

0 Wyatt Keller over 4 years ago in reply to Wojciech Obrebski

TI__Guru** 105590 points

Hello Wojciech,

It looks like the SOH load may be a private parameter, but also looking at your capacity the default value shouldn't cause any large errors.

I would make sure you are getting a Qmax update and Ra update, then check how the SOH is tracking.

Sincerely,

Wyatt Keller

0 Wojciech Obrebski over 4 years ago in reply to Wyatt Keller

Intellectual 480 points

Thanks Wyatt,

I will make some discharge/charge cycles and i will return to you with results (this will take some time; one cycle is more then 30 hours...)

0 Wojciech Obrebski over 4 years ago in reply to Wojciech Obrebski

Intellectual 480 points

I finished with discharge/charge cycles and realized that SOH strange behavior was by mistake in implementation - now everything is ok. But i have another problem with behavior after sleep but i will describe it in new thread.

Thanks for support!

Power management

Power management forum

BQ27421-G1: BQ27421-G1A SOH status always 0x00