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Original question:

BQ34Z100-G1: GPCRB report T Rise and T Time Constant is out of range

BQ34Z100-G1: Question regarding T Time Constant and T rise parameters

Andrew Supercharged
Prodigy 180 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: GPCRB

I am using this IC in a drone application where the ambient temperatures can range from -20C to 50C. The cell temperature ranges from ~0C up to 65C depending on the environmental conditions, though, they are usually biased around the outside temp (colder days yield colder batteries, hotter days yield hotter batteries). 

I have noticed some estimation inaccuracies when my battery is in the extreme heat and I am wondering if my settings for these two parameters: T rise, and T time constant, are correct. Can you provide an explanation of these two parameters and mention how they effect the IT algorithm? Information I have seen in data sheets do not provide any information on these parameters. 

Thank you,

> Andrew

  • 0
    TI__Mastermind 42535 points

    Hi Andrew,

    T Rise and T Time constant compensate for temperature change due to self heating of the cell during use. They can be calculated using the GPCRB tool.

    T Rise gives the thermal rise factor that is used in the single time constant heating-cooling thermal modeling. If set to 0, this feature is disabled and simulations in the IT algorithm will not account for self-heating of the battery cell. Larger values of T Rise lead to higher temperature rise estimates for the IT simulation.

    T Time Constant is the thermal time constant that is used in single time constant heating-cooling thermal modeling. The default setting can be used, or it can be modified to improve low-temperature accuracy if testing shows the model does not match the actual performance. T Time Constant defaults to 1000. This is sufficient for many applications. However, it can be modified if better predictive accuracy at low temperatures is desired.