The necessary tools for the experiment: EV2300/2400, voltmeter, Battery Management Studio software.
1. Obtain the battery cell chemID and
use bqStudio or the battery charge and discharge aging cabinet to record the time point, voltage, current, temperature and other data of the following process.
(1) Fully charge the battery, let it stand for 2 hours, empty the battery at a speed of 0.1C~0.2C, and let it stand for 5 hours.
(2) Fill in the form roomtemp_rel_dis_rel.csv with the data for the period of 2 hours of standing, emptying, and standing for 5 hours, and fill in config.txt, and pack it into a zip. (Format reference document: Simple Guide to Chemical ID Selection Tool (GPC))
(3) Upload the zip package to the website GPC, the final report will be sent by mail, and the best chemID will be marked in the report. If the error is less than 3%, it is credible.
If the above steps do not inspire your experiment, please refer to my previous blog "TI Fuel Gauge-Obtaining Chemical ID" .
2. Configuration parameters
(1) Use bqStudio to configure parameters for the electricity meter memory, such as battery power, voltage, jeita performance, etc.;
(2) Perform voltage and current calibration. Pay attention to the reduction factor when calibrating the current. For example, if the actual capacity is reduced by several times, the current should be reduced by several times accordingly;
(3) Fill in chemID;
(4) Send 0x41 to reset, and then export the gg file.
3. Self-learning
(1) Disconnect the battery for external output power supply, and other small batteries can be used where power is needed.
(2) Empty the battery and let it stand for more than 5 hours. (Standing is for the voltage of the battery to no longer change, so you must disconnect the battery to supply power to any other devices before standing.)
(3) Send 0x21 command (IT_ENABLE command) to the fuel gauge in bqstudio, the purpose is to enable the impedance tracking function of the fuel gauge. After sending the command, read the register and the flag bit to see if the value of the corresponding flag bit changes, at this time UpdateStatus=0x04;
(4) Fully charge the battery and let it stand for 2 hours. Use bqstudio to read the flags and registers. If the update is successful, UpdateStatus=0x05. If UpdateStatus is still 0x04, you can stand for another hour, if it has not been updated, you need to empty the battery and repeat this step;
(5) Empty the battery at a speed of 0.1C~0.2C and let it stand for 5 hours. If the update is successful in this step, UpdateStatus=0x06, otherwise repeat the above charging and discharging process again. Reference document: How to run an Impedance Track gas gauge learning cycle
Update ra flag, qmax, modify gg file, cycle count (set the number of cycles to 0), update status (set to 0x00 or 0x02) and other values to generate mass production files .
"Official BQ40Z80 Cycle Learning Export Production Document Manual"
4. Burn
5. Error estimation
Record a complete discharge data (can be obtained from log or bqStudio), record the current time point, temperature, voltage, power, current, power percentage every 10s or so, download the form AccuracyWalk_Through.zip, fill in the data accordingly, Automatically generate SOC accuracy data and graphs. The principle is that the integral of current over time is equal to electricity.
Reference document: How accurate is your battery fuel gauge
Other similar blogs or community forums:
"Basic introduction and FAQ of TI single-section fuel gauge"
"Design for mass production of bq27520 fuel gauge"
"How to Export DFI or SENC File in Gauge Studio"
"TI Fuel Gauge Training" (I have a lot of thoughts and conclusions from this blogger, thank you here)
Other considerations:
(1) In the second step above, you can not set the value of each register one by one, you can import the srec file of the previous similar project (the cut-off voltage, current, each protection parameter are the same), and check the impedance tracking after importing Whether the learning has been completed (ra flag, qmax, etc. are set, pdate status=0x06), cycle count (set the number of cycles to 0), update status (set to 0x00 or 0x02), write the chemical ID, and perform calibration You can proceed to the following cycle learning;
(2) In the above step 2 (configuration parameters), confirm that the relevant parameters have been set, calibration and CHEM_ID selection can be carried out, send the command 0x41 to reset, export the DFI file or SENC file for backup ( this action is for the above (1) Prepare for the situation in );
(3) After configuring the parameters, after the battery cell is emptied and left for 5 hours, before starting the cyclic learning, be sure to send the 0x21 command (IT_ENABLE command) to enable impedance tracking;