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BQ34Z100-G1 parameter configuration for 4S4P LiFePO4 battery

Abhishek Mathur
Prodigy 60 points
Other Parts Discussed in Thread: BQ34Z100-G1, BQSTUDIO, EV2400

I am using the BQ34Z100-G1 to measure the battery level of a AA Portable Power LiFePO4 Battery Pack (77WH-6000mAh-12.8V nominal 4S4P configuration). The battery is charged upto 14.5V with a TI BQ24620RVAT chip.

I am using a EV2400 on the TWI bus of the BQ34Z100-G1 to send the parameters via BQstudio 1.3.45.

I have configured the various parameters like design capacity, number of series cells, pack configuration registers as shown in the SREC files attached.

When I try to calibrate, the board calibration( CCoffset and Board offset) works. I measured the current with an Ammeter as 1339mA, so I entered that. But the current in the meter now appears as -1339mA. (The polarity is wrong)

The voltage calibration does not take in the correct value (Either 14500mV or 3625mV).("Beyond the allowed range") Currently it shows a voltage of 196mV when the actual voltage on the battery is 14.3V. (Sense resistor is 10mOhms and Rseries is 240k). The highest votlage I have been able to enter is around 250mV.

The schematic is below.

0100_0_16-bq34z100G1.bq.zip

  • 0
    TI__Guru 73830 points

    The files in the zip file are empty. Here are a few comments.

    • I negative sign needs to be placed in the value entered with calibrating with a discharge current. So, enter -1339mA and the current should report properly.
    • Do you have the VOLSEL bit set in the Pack Configuration register. This bit must be set to enable the external resistor divider network.
    • The resistor divider network is setup to measure up to a 14V stack voltage. If you want to support more voltage, then you should increase the value of R152.
  • 0 in reply to ThomasCosby
    Prodigy 60 points

    Here are the regenrated files. They should have the data. I changed the R152 resistor to a 249k to allow upto 14.5V as per the formula. It now shows 420mV in the battery level on the left in BQ studio. The VOLTSEL bit has been set to 1 (green) Still does not let me calibrate to 14500mV

    4848.0100_0_16-bq34z100G1.bq.zip

  • 0 in reply to Abhishek Mathur
    TI__Guru 73830 points
    I checked the srec and VOLSEL is disabled. GREEN = 0 and RED = 1 in bqStudio. You should be able to calibrate the voltage after you set this bit to 1.
  • 0 in reply to ThomasCosby
    Prodigy 60 points

    Here are the new SREC files with the VOLTSEL bit enabled. I set the design energy scale to 10 as it is a 77Wh battery and set the corresponding parameters. Now the highest calibration voltage allowed is 2500mV. (still at 0%)

    7612.0100_0_16-bq34z100G1.zip

  • 0 in reply to Abhishek Mathur
    TI__Guru 73830 points
    I am not sure what the problem is with your setup. I programmed your srec and was able to calibrate the pack. You could try reloading bqStudio and make sure the use the Run as Administrator selection.
  • 0 in reply to ThomasCosby
    Prodigy 60 points
    Thank You! This helped!
    Reloading BQ studio with admin privileges did not make a difference. But I moved to a second board set which has a 189mA load on the output and imported the SREC files in and now I am able to program the voltage level on this chip to 14.5V.
    The polarity of the current is still wrong. I tried calibrating while it is charging and while it is discharging with both -ve polarity and +ve polarity voltage. It still shows a + current when it is on battery only (with load) and a negative current when it is charging.
    Also, I seem to have "sealed" the memory at one point in this process which imports with the SREC file. When the unseal or the unseal full access command is used, it stays only until the next reboot of the chip. Can I unseal this chip permanently? (Disable authentication)
  • 0 in reply to Abhishek Mathur
    TI__Guru 73830 points
    The only way to keep the gauge unsealed is to reload the default srec file. You can save a gg file, program the default srec, program the ChemID and then reload the gg file. Be sure to have it load the calibration data as well. Do you have the sense resistor positioned in the proper direction? The SRP pin should be connected to BAT-.