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BQ40Z50-R2: How to safely test a new board

haku15
Prodigy 80 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50, EV2400, BQSTUDIO, BQPRODUCTION

Hi,

I'd like to design a board for the bq40z50-R2 to build my own lithium battery pack, but I am still unsure how can I test it safely.

I am worried that an error in my board design or in the configuration of the bq40z50 might cause a short circuit or some other unsafe condition to the batteries.

I was thinking of buying for the first tests a 2s or 3s commercial Lithium battery pack with protection (short circuit, overvoltage, undervoltage per cell,…) already integrated (unspecified IC).

I am unsure whether that protection circuit might interfere with the normal operation (measurement accuracy,…) of the bq40z50, invalidating the test.

I could also use stricter protection thresholds for the bq40z50:

For example I'd set 4.23V for overvoltage on the bq40z50, whereas the protection IC in the commercial battery pack is set for 4.35V. This way I'd see if the bq40z50 sets the appropriate flag during an overvoltage test.

During such a test, can I also use a multimeter to monitor the batteries voltage or would this also interfere with the protection ICs?

 

Once these first tests are done, I'd proceed using the designated batteries for my battery pack (branded 18650 Li-Ion or RC LiPo without protection IC already in them).

 

Could this work or do you suggest an other procedure/hardware?

 

I am doing this as private person (as a maker), so I have no access to costly equipment or facilities (or chemical fuses).

 

Thanks in advance for you help

Sincerely

  • 0
    TI__Genius 12215 points

    Hi

        For debugging and engineering test, you can download latest version bqStudio from TI website and apply a USB-SMBUS interface EV2400 from TI website, you can read register from the device, and manipulate FETs as desired by sending command to the device.

        For production, you can download bqProduction from TI website, the interface tool is also EV2400

  • 0 in reply to Steven Yao
    Prodigy 80 points

    Hi  Steven,

    thanks for your help.

    I know that already, I watched the training materials and the manuals from TI and I plan indeed to use bqStudio with EV2400.

    My questions are however else: can I use protected batteries and also monitor the batteries voltage with a multimeter, while I also read the parameters in bqStudio? Or does that interfere with the operation of bq40z50?

    I will test the bq40z50 before connecting the batteries, but what if an error in my bq40z50 board  manifests itself only when the batteries get connected and a short circuit happens? That's why I'd like not to do the first test with unprotected batteries.

    Thanks

  • 0 in reply to haku15
    TI__Genius 12215 points

    Hi, Kako

        As for bq40z50 application, the protection FETs for charge and discharge are at high side, i.e., located on the path from Bat+ to Pack+, so even with protection triggered, communicating with gauge is still possible.

        To verify the bq40z50 initial design, I think you may need to setup a typical test system with four channel power supply to simulate the battery and verify the basic function of the PCM, like power consumption current under different working mode like sleep, shutdown and normal. The consumption current can be acquired by connect a DMM in series to the cell connect input pin and power supply output.

        Then you can verify each protection function by manipulating the voltage on each channel for voltage related protection and applying a set current to the sense resistor for current related protection.

       

    Thanks

  • 0 in reply to Steven Yao
    Prodigy 80 points

    OK, thanks Steven for your help!