BQ34Z100-G1: Sudden Drop in SOH using Parallel LiFePO4 Batteries

Aaron Lal

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ25703A

Hello TI,

I'm encountering an issue while conditioning the gas gauge for two 20Ah batteries connected in parallel (Total capacity of 40Ah, and energy of 512Wh).

The problem occurs when I have fully charged the battery (using a BQ25703a charger device). The SOH suddenly drops from 98% to 1% several hours after the charging is terminated. Full charge capacity and SOC also drop to zero.

What could be the root cause and how can I resolve this issue?

Kind regards,

Aaron

over 1 year ago

0 Steven Yao over 1 year ago

TI__Genius 12215 points

Have the flash data be configured correctly? I mean the chem ID and learning cycle are selected and done respectively in prior to the charge discharge test? Also need to make sure the IT Enable command has been sent

0 Aaron Lal over 1 year ago in reply to Steven Yao

Prodigy 160 points

Hi Steven,

I selected LIFE for chem ID as I'm using a LiFePO₄, Is this correct?

I have attempted the learning cycle but each time it gets stuck and I have to reload the firmware (see my other posts on this).

At this stage, my process is to run a few charge-discharge cycles to get an approximation. I will do a learn cycle once the hardware is capable of charging/discharging at C/5. Will this process work? Or does the learn cycle have to be done first?

0 Steven Yao over 1 year ago in reply to Aaron Lal

TI__Genius 12215 points

Aaron

You need to download a correct ID, what is you present chem ID in the gas gauge

0 Aaron Lal over 1 year ago in reply to Steven Yao

Prodigy 160 points

CHEM_ID is 0x0107

0 Steven Yao over 1 year ago in reply to Aaron Lal

TI__Genius 12215 points

Aaron

This is not an ID for LiFe Battery, please try to find a correct chem ID and download the ID to the device followed by a learning before accuracy test. A correct ID shall be found according to the cell model, if not applicable, if not available please contact local TI FAE for help

0 Aaron Lal over 1 year ago in reply to Steven Yao

Prodigy 160 points

Hi Steven,

Will my parallel battery setup be workable here? As in would it be equivalent to a single 40Ah battery?

It looks like I will have to collect data and use the GPC tool to find a suitable chemistry ID.

0 Steven Yao over 1 year ago in reply to Aaron Lal

TI__Genius 12215 points

Hi, Aaron

You can use it a a single 40Ah Battery, please be noted you need to set Qmax and Design Capacity to 40Ah as the initial value

0 Aaron Lal over 1 year ago in reply to Steven Yao

Prodigy 160 points

Hi Steven,

Ok. Because the Qmax and Design Capacity registers max out at 32000mAh, I set them to 20000mAh and scaled all current measurements by a factor of 2.

0 Steven Yao over 1 year ago in reply to Aaron Lal

TI__Genius 12215 points

Aaron Lal

Yes, you are correct

Power management

Power management forum

BQ34Z100-G1: Sudden Drop in SOH using Parallel LiFePO4 Batteries