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BQ27542-G1: Expected Temperature Measurement Accuracy when using NTC=10K 1%

Fabio Bucci
Intellectual 2635 points
Part Number: BQ27542-G1

Team, 

- What’s the expected temperature measurement accuracy when using NTC=10K 1% , B25/35=3435 1%?

- Is there any specific action (for example calibration) on the pack maker side to make sure the expected level of accuracy is achieved? If so, can you please provide more details?

 

It looks like the pack maker is currently providing a +/-3C accuracy which is pretty surprising.

 

Please let me know – it’s a pretty urgent matter.

 

Thanks

  • 0
    TI__Guru* 76230 points
    Hi
    High Temperature accuracy is not an absolute requirement for the algorithm. +/-3deg is not terrible. They customer can perform temperature calibration to improve the temperature accuracy given that it appears they are using the recommended 10k ntc. See user guide on performing temperature calibration. btw, is the customer experiencing this +/- 3 deg C temp accuracy at room? Typically error in temperature measurements occur at the lower extremes, i.e colder temperatures.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Intellectual 2635 points
    Hi Onyx,

    what's the highest achievable accuracy when using a NTC=10K 1% , B25/35=3435 1%?

    Apart from the +/-3deg that looks like very coarse, customer wants to figure out whether the pack maker has done all it takes to achieve the highest possible accuracy with a 10k NTC or not.

    And if not, what he should do to get there.

    Please let me know
    Thanks
  • 0 in reply to Fabio Bucci
    TI__Guru* 76230 points
    You can achieve up to +/- 1 degC accuracy at room temp. I mentioned performing temp calibration to help get the 1degC accuracy. See EVM userguide for directions on how to carry out temp calibration.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Intellectual 2635 points

    Hi Onyx,

    is the temp calibration supposed to be done by the pack maker or the end customer owns it?

    Please let me know

    Thanks

  • 0 in reply to Onyx Ahiakwo
    TI__Intellectual 2635 points

    Hi Onyx,

    can you please share more details on the measurement setup the pack maker should use to calibrate the gauge and get to a 1C accuracy?

    Ideally, I would need the description of the entire process along with equipment required.

    Please let me know

    Thanks

  • 0 in reply to Fabio Bucci
    TI__Guru* 76230 points

    Hi 

    I did mention earlier that  the EVM user guide describes how to perform temp calibration. see section 8.5. I have to emphasize that high temperature accuracy isn't required. +/- 3 degC accuracy is sufficient for the gauges normal operation 

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Intellectual 265 points

    Hi Onyx,
    we also have the same question, and use the same NTC for the battery pack(NTC=10K 1% , B25/35=3435 1%),
    in the EVM user guide, only mention that as below:
    "Measure the temperature for PACK. Type the temperature value into Enter Actual Temperature"

    Have some question:
    1. do you have the picture, that shows the detailed calibration setup? if we follow this setup, the 1% temperature accuracy can be guranteed? correct?
    2. this temperature measurement is on pack outside? CELL? or the tempeature on the NTC resistor?
    3. based on your calibration experience, what temperature meaurement instrument is suggested for calibration?

    4. you mentioned: "You can achieve up to +/- 1 degC accuracy at room temp", so how about the temp accuracy under cold temp(0C, -20C) and high temp(such as 45C, 50C)

  • 0 in reply to Mobydata - Tony Liu
    TI__Mastermind 24870 points
    Please refer to the EVM user's guide.