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BQ78PL114; Charge Suspend vs Overtemperature Charge

Nigel Wade
Prodigy 225 points
Other Parts Discussed in Thread: BQ78PL114, BQ78PL116

On a BQ78PL114 or BQ78PL116 what is the intended use of Overtemperature Charge? Isn't it made redundant by Charge Suspend - Temperature? 

The seem to have very similar functionality apart from the timer feature within Overtemperature Charge.

If Overtemperature Charge is required, why is there not a 'charge undertemperature' function, with a timer, like there is for discharge?

  • 0
    Prodigy 225 points

    I would very much appreciated a response to this question from TI.

    Even if it is just to say 'This question is pending an answer from a design engineer' or 'We can not answer this question due to internal restrictions'.

  • 0 in reply to Nigel Wade
    Prodigy 225 points

    Does anyone from TI have an answer to this about the BQ78PL114 / BQ78PL116 ?

  • 0 in reply to Nigel Wade
    TI__Intellectual 1505 points

    Hi Nigel,

    The Charge Suspend and Overtemperature Charge offer similar functionality as you have noticed.

    The Overtemperature Charge offers the user more programmability on when to respond to the OT condition through a programmable timer.

    Also, the Overtemperature Charge is a First Level Protection Feature and hence can be reset and programmed to respond at varying speeds. (Refer Page 17 of TRM)

    The Charge Suspend -Temp occurs during Charge  and does not offer any programmability on the response time. It however, provides the user, the ability to set a Charging Temperature range.

    These part features are provided to give the user maximum flexibility in configuring their Battery Management Solution using the bq78PL116/114.

     

  • 0 in reply to Benjamin Sarpong
    Prodigy 225 points

    Hi Benjamin

    Thank you for the clarification between Charge Suspend and Overtemperature Charge.

    However, in order to give the user maximum flexibility, why is there not a first-level 'Charge Undertemperature' function with a programmable timer like there is for discharge?

     

  • 0 in reply to Nigel Wade
    TI__Intellectual 1505 points

    Hi Nigel,

    The "Charge Undertemperature" function is covered under the Precharge Temperature Function.

    Precharge is only allowed when all the cell temperatures are above the set PreCharge Temp. (Refer to Page 4 of the TRM)

    Thanks,

    Benjamin

  • 0 in reply to Benjamin Sarpong
    Prodigy 225 points

    Hi Benjamin

    The way I read the TRM, it is Charge that is allowed when all temperatures are above the 'Precharge Temperature', whilst PreCharge is allowed down to the 'Charge-Inhibit Temperaure' or 'Charge-Suspend Temperature', depending on the value of battery current. Is this correct?

    Also, as confusing as the naming is, 'Precharge Temperature' is almost equivalent to a 'Charge Undertemperature function', except there is no timer. Why is there no timer for this function, yet there is for 'Discharge Undertemperature', 'Overtemperature Charge' and 'Overtemperature Discharge'?

    Thank you

    Nigel

  • 0 in reply to Nigel Wade
    TI__Intellectual 1505 points

    Hi Nigel,

    PreCharge is part of the Charge Profile for the battery. It is the start of Charge and hence, the temperature has to be above the Precharge Temp for charging to start.

    One reason there is no timer might be, because this is an initial condition. If the temp is low, charge will not start. If the temperature drops during charge, you stop charge 2 seconds later (the fault is evaluated every 2 seconds). I agree the naming could be clearer.

    Ben