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Qmax Update - 5 hour waiting Time

Anthony Elbancol
Prodigy 215 points

In SLUA458, page 45 under "Update of Qmax" the following statement is made:

"A well-relaxed state is detected if dV/dt<4 µV/s or maximal waiting time of 5 hours is exceeded."

My question is regards to this 5 hour waiting time.  Will an OCV measurement after this 5 hour waiting time is exceeded even a sudden pulse of current just so happens to occur during this time?  Is this measurement occurring after 5 hours compensated in any way?

Thanks,

Anthony

  • 0
    TI__Expert 8230 points
    Hello Anthony,

    The gauge will take an OCV measurement based on which of the two conditions is met first: dV/dt condition or 5 hours have past. If the cell is in relaxation, and the OCV measurement hasn't been taken because the dV/dt condition hasn't been met, and a current pulse happens, it will take the cell out of relaxation. Depending on the magnitude and duration of the pulse, the relaxation time of the cell will vary, but the gauge will continue monitoring looking for that dV/dt condition or take a measurement after 5 hours have passed.

    Thanks.
  • 0 in reply to Fernando Lopez
    Prodigy 100 points

    So what kind of embedded application allows for up to 5 hours of stabilization with no load and again after charging?

    I suppose something with cells that are removed an placed in a separate charger, but for something like say a cell phone, you are normally either charging or discharging with no significant relaxation time at either end of the charge cycle.

    Can Impedance track actually work under these kind of applications? Can the times or dV/dT conditions be changed - allowing for a less accurate solution but one that is more practical from a user's standpoint?