BQ34Z100: How to set parameters of BMS chip in bqStudio

Hi Seognjin Hwang,

Here are the basic steps to getting started with the BW34z100. Please also refence the EVM user guide and quick start guide if you are testing on the EVM, which i recommend.

It is important to remember that the BQ34z100 is a top of stack gauge and does not monitor cells individually. Due to this it is critical that a battery monitor is paired with the BQ34z100 to balance the cells. It is also important that the thermistor is placed on the battery pack rather than the PCB board.

Linked is the BQ34z100 TRM, this will be your best friend, it describes every register in BQstudio: BQ34Z100-R2 Technical Reference Manual (Rev. A) (ti.com)

1) Firmware

Linked is the BQ34z100 FW home page. BQ34Z100-DEVICE-FW Firmware | TI.com

2.02.31 is R2

0.16 is G1

0.07 is original FW

2) Voltage divider

The input for the Bat pin on the BQ34z100 must be less than 1V to avoid damaging the device. This is done with a voltage divider on the BAT pin and configuring the “Voltage Divider” parameter in BQstudio. The default Voltage divider value is 5000, this indicates a 5000mV:1000mV voltage divider (this is the internal divider). This will need to be reconfigured for the ratio of the voltage divider needed for the customers application. (XXXXmV:1000mV) Section 3.4 in the TRM describes the voltage divider. It is also important to enable the “VOLTSEL” bit in the Pack Configuration Register Bits. (Section 3.3.1) This will notify the gauge to use the external voltage divider rather than the internal one.

This documentation also describes the voltage divider and additional information regarding using the BQ34z100 with large voltages and currents: bq34z100-G1 High Cell Count and High Capacity Applications

3) Calibration

                It is important that the gauge is accurately reporting Voltage, Temperature, and Current. The videos linked below go over the calibration process using BQstudio.

Perform voltage calibration with the BQ34Z100-G1 | Video | TI.com

Perform current calibration with the BQ34Z100-G1 | Video | TI.com

This thread also describes the calibration process: (+) BQ34Z100-G1: Commands for calibration procedure - Power management forum - Power management - TI E2E support forums

4) ChemID

In order for the gauge to accurately report SOC it is critical that a proper ChemID match is obtained. We have characterized over 5000 cells in our data base. The GPCCHEM tool will match the cells you are using with the ChemIDs in our system and return the best matches, we recommend using a with DOD% error 3% or less.

GPCCHEM tool: GPCCHEM Application software & framework | TI.com

Steps on how to use the GPCCHEM tool: Simple Guide to Chemical ID Selection Tool (GPC) (Rev. A)

5) Scaling and initial configuration:

                Initially critical parameters will need to be configured, these are “Design Capacity”, ”Charge Term Taper Current”, “DSG Current Threshold”, “Chg Current Threshold”, “Quit Current”, and “Term Voltage”. The document linked in step 6 describes these parameters.

Scaling may also be required if the values attempted to be entered are to large. There are 3 types of scaling on the BQ34z100-R2, voltage, current, and energy. EX: if your design capacity is to large for the integer size limitations on the device a scaling factor will need to be applied. Since design capacity is reported in mAh a current scale will need to be applied. You will then divide all parameters in BQstudio reported in mA, A, Ah, mAh, etc by the current scale factor selected. If you apply a voltage scale, scale all values reported in V, mV, etc. If you apply an energy scale, scale all values reported in W, Wh, etc.

This thread also explains scaling factors: (+) Bq34z100-g1 question regarding scaling factor and design energy field - Power management forum - Power management - TI E2E support forums

For LFP cells please enable both the “LFPRelax” bit and the “DoDWT” bit both found in the Pack Configuration B Register. (Section 3.3.2 TRM)

Load Mode and Load Select (section 3.2 in the TRM) should also be configured based on an expected load.

6) Learning cycle:

                Once the device has been configured properly, the learning cycle process can begin. The learning cycle will help optimize the resistance tables for the cells being used. The link below describes the steps.

                Achieving The Successful Learning Cycle (tij.co.jp)

7) Ra0/Rb tweak:

                After all steps above are completed tweaking the resistance values may be needed. This can be done with our other GPC tools, but only if necessary.

Additional Helpful Documentation:

General Impedance Track: Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm (Rev. A)

FAQ for BQ34z100: (+) [FAQ] BQ34Z100-G1: BQ34Z100-G1 FAQs - Power management forum - Power management - TI E2E support forums

How to exit ROM: (+) BQ34Z100-G1: How to exit ROM mode - Power management forum - Power management - TI E2E support forums

How to use advanced comms: Using I2C Communications With the bq34110 bq35100 and bq34z100-G1 Series of Gas

Understanding the BQ.FS: Gauge Communication

Please let me know if you have any questions.

Regards,

Diego