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BQ34Z100-G1: BQSTUDIO Full Charge Detection for PbA

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO,

Hello,

For PbA, the taper method is used (FC Set %=-1) for detecting a Full Charge.

The TRM pg60 places great importance on the timing of charge cut-off using criteria a,b,c as stated here:

However, the TRM pg31 states the criteria differently here:

Please clarify for PbA and suggest the BQSTUDIO watch window parameters for supporting a proper charge cut-off.

Also please note, that for PbA there is a phase 1 charge voltage and a phase 2 charge voltage.


I find only the cell charge voltage T#-T# parameters defined in the DF Configuration>Data section.
Which charge voltage is used here for PbA?
If this is to define the phase 1 voltage, then where is the phase 2 voltage defined?

Sincerely,

Rom

  • Hello Rom,

    Page 60 is part of the guide to help debug issues with the learning cycle. Page 31 has the actual criteria for full charge conditions.

    The BQ34Z100-G1 does not support the two charge voltage levels. The Charge Efficiency is used for lead acid batteries during charging. The gauge does not provide a float voltage to the charger.

    Sincerely,

    Wyatt Keller

  • Hello Wyatt,

    With regard to Criteria 1b, if the Current Taper Window is 40s,  I'm assuming I would need to calculate the difference in a capacity parameter reported every 40s .  Which capacity variable  may be used for this in the Watch Window?

    What other BQSTUDIO watch window parameters do you recommend for the learning cycle?

    Do you mean that for learning purposes, a single charge voltage level is required?
    Can this gauge provide high accuracy performance only when using a single charge voltage in the field application?

    Sincerely,
    Rom.

  • Hello Rom,

    This is not needed, the only time I've seen the accumulated capacity parameter not met is with very small capacity packs (~100mAh)

    I would recommend using the logging feature in BQStudio in order to keep track of the behavior since it can take a long time to run the learning cycle and you can always reference back to it for any issues.

    The multiple level charging voltage is not a requirement for lead acid, it is just a feature some chargers have to keep the battery topped off.

    Sincerely,

    Wyatt Keller

  • Hello Wyatt,

    Thank you for the helpful perspective on when the accumulated capacity criteria is important.  My pack is big, so I will disregard it.
    The other two criteria are easily monitored when watching voltage and current.
    I'm also using the logging and autoexport features in BQStudio, but those won't help with real-time monitoring needed for proper Charger Cut-Off timing.

    Most Lead Acid chargers on the market are 3 phase, meaning two voltage levels.
    I understand the gauge has some ability to compensate for charge efficiency but not two charge levels.
    For learning it's not an issue to use a single voltage level, i.e. 2 phase charging.


    In practice, the gauge with PbA batteries will mostly see 3 phase charging, and therefore I expect gauging error from it.

    Has gauging accuracy been studied for 3 phase charging in PbA applications?
    Or any estimated impact assessments?

    Sincerely,

    Rom