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BQ27426: BQ27426 | Production Test Recommendations

Antenna_Head
Genius 13230 points

Part Number: BQ27426

Team-

We have a customer that is building a product using the BQ27426.

They have a quick battery test prior to integrating it into the product, but they would like to fuel gauge to begin adapting to the individual cell before leaving the factory.

Note that the raw batteries they receive are only charged to about ~30% capacity for regulatory reasons.

Please recommend the fastest/easiest series of steps they should follow in a production environment to get the BQ27426 to begin adapting to the cell attached to it.

Thanks, Best, S. Dunbar, AFA Colorado

  • 0
    TI__Mastermind 27145 points
    Hi Antennahead,

    Do you know if they have performed a learning cycle with one of their batteries? This would update Qmax and the Ra table specific to their battery. They could then export memory as a "golden image" and use this to program the rest of their gauges.

    Steps for learning cycle:
    1. discharge to empty
    2. wait for the gauge to take an OCV measurement (may take 30 min up to 5 hours depending on battery)
    3. charge to full
    4. wait for the gauge to take another OCV measurement (1-2 hours)
    5. discharge to empty at a rate between C/5 and C/10
    6. wait for another OCV measurement (up to 5 hours)

    Do the learning cycle on one board, export memory and use that image to program the rest. This should adapt the gauge to your specific battery.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    TI__Genius 13230 points

    Ben-

    Yes, they can/have done a learning cycle.  The main issue is what to do in a production environment, where unit-to-unit variation in batteries can be significant.

    Doing a full learning cycle in production would be far too time consuming.

    Were looking for something more abbreviated- what's the minimum needed to get the gauge to do an update at least to Qmax?

    Best, Steve

  • 0 in reply to Antenna_Head
    TI__Mastermind 27145 points
    Hi Steve,

    The gauge does have a feature called Fast Qmax which would allow you to update Qmax without doing a full learning cycle. You would need to charge the battery to 45-50% allow the gauge to take an OCV measurement, then discharge to <4%. Before beginning the discharge, make sure QMAX_UP is cleared. The gauge should update Qmax at the end of discharge.

    Best Regards,
    Ben lough