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BQ35100EVM-795: BQ35100EVM-795

Rampal Chasta
Prodigy 30 points
Part Number: BQ35100EVM-795
Other Parts Discussed in Thread: BQ35100

I have the following query regarding the use of BQ35100EVM-795 board:

We are using lithium thinonyl chloride battery for a product of 10 to 12 years life and would like to ensure the battery capacity (mAh) in production site before mount in product. Now I have following question to answer: 

  • Does this EVM board is directly shows the battery capacity  (mAh)       
  • How much time does it take to measure capacity of battery in terms of mAh? We can spare less than 30 sec on our production line.
  • How much it discharges battery for this test? In other words, how much current drawn by EVM boards while checking the battery capacity?
  • What about the status of passivation layer of battery means does it breaks while capacity measurement?
  • Does it require the external supply to power up the board or it will take supply from Battery terminal (BAT+ & BAT-) while battery is connected at BAT+ & BAT- header pins for capacity measurment.
  • Is there any commercial product used for battery capacity measurement in market?

Regards

Rampal Chasta

  • 0
    TI__Guru 52115 points

    Hi Rampal,

    My colleague who is the expert on this device is on vacation this week. We should be able to get back to you early next week.

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 30 points

    As replied by harmeet on mail,

     I understand that this IC BQ35100 works in three modes of operation i.e. Accumulator mode, State of Health (SOH) mode and End of service (EOS) mode.  Now I have following concern in my mind: 

    1. As datasheet mentioned SOH feature is only applicable for lithium manganese dioxide (Li-MnO2) chemistry cell and we are using lithium thionyl chloride (Li-SOCl2) cells and how could this mode will help in our application. Its value is showing in % in would like to know whats it state and how it is calculated.

    2. What about the mode of End of service (EOS) and how it's find the Depth of discharge (DOD) and calulate the battery capacity life in application software.

  • 0 in reply to Rampal Chasta
    TI__Genius 10370 points

    Rampal,

    • Does this EVM board is directly shows the battery capacity  (mAh)       
      • [Vos] No This gauge does not report a mAh. If used in Accumulation mode it will reported capacity used while the gauge was awake and measuring
    • How much time does it take to measure capacity of battery in terms of mAh? We can spare less than 30 sec on our production line.
      • [Vos] Depends on the mode of operation. ACC mode will run as long as you tell it to count. SOH mode takes less than 2 Seconds, and EOS Mode should take around 16-20Seconds depending on the duration of the pulse load we are measuring. 
    • How much it discharges battery for this test? In other words, how much current drawn by EVM boards while checking the battery capacity?
      • [Vos] Please see our datasheet. it depends on how long your system leaves the different modes active for
    • What about the status of passivation layer of battery means does it breaks while capacity measurement?
      • [Vos] This gauge does not apply enough of a load to eat the passivation layer. However this gauge relies on consistency. So we expect the passivation to be the same between learning pulses.
    • Does it require the external supply to power up the board or it will take supply from Battery terminal (BAT+ & BAT-) while battery is connected at BAT+ & BAT- header pins for capacity measurment.
      • [Vos] Power is drawn from the GE pin, which is used to wake us up. You can tie this to the battery through a FET which is controlled by the MCU. Or tie it directly to a MCU.
    • Is there any commercial product used for battery capacity measurement in market?
      • [Vos] Nothing other than this bq35100 that i am aware of. 

    1. As datasheet mentioned SOH feature is only applicable for lithium manganese dioxide (Li-MnO2) chemistry cell and we are using lithium thionyl chloride (Li-SOCl2) cells and how could this mode will help in our application. Its value is showing in % in would like to know whats it state and how it is calculated.

    [Vos] EOS mode does report an SOH %, but depending on how flat your impedance profile is accuracy might not be very good when starting out. As battery impedance increases SOH should become more accurate

    2. What about the mode of End of service (EOS) and how it's find the Depth of discharge (DOD) and calulate the battery capacity life in application software.

    [Vos] it does impedance correlation. 

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 30 points

    Thank u very much for reply.

    1. Terms and condition used in battery management studio in EVM board for accumulator mode to find out the charging capacity of battery means how software shown the value?

    please send some SOP if available.

    2. What value shows in application software (Battery management studio) for Impedance correlation to find the battery capacity,

    My aim is to find out the remaining battery capacity before used the same in product or any equipment.

    Regards

    Rampal

  • 0 in reply to Rampal Chasta
    TI__Genius 10370 points

    Rampal,

    1) Accumulation mode will coulomb count when GE is high and Gauge start is sent. IF you send gauge stop it will commit the passed charge to (uA resolution) to flash. If you just power down it will start from the last flash update. It only counts it does nothing with the actual battery. You host system would need to to the math, 

    2) In EOS mode you get SOH% (100-0) this is an impedance correlation against our TI chemID. You also get MeasuredZ that you can do your own calculation. Last you get an EOS flag that will alert you when you have reached the exponential growth part of the curve. 

    You do not get any sort of capacity remaining readout in any mode.

    Thanks,

    Eric Vos