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How Important is Temperature Sense When Charging a Li-Ion Cell?

Charles Gervasi
Expert 2270 points
Other Parts Discussed in Thread: LM3658

I am using the LM3658 to charge this Li-Ion Polymer cell.  I've had good results in the lab. 

Does anyone know the frequency of a high-temperature failure mode of Li-Ion cells?  Is this something likely to happen as the cell ages?  Or is it only something that happens if you expose the cell to excessive current, temperature, etc?

  • 0
    Genius 3290 points

    I don't think there is an answer to this question without more input.
    How is "high temperature" defined?
    How is "failure mode" defined?

    It is not clear to me what the root concern is.   As you may know, higher temps accelerate aging. However, unless the temps exceed the specified limits, "failures" should not occur.

    Does this help?

  • 0 in reply to PaulSchoenke
    Expert 2270 points

    The fact that many Li-Ion charging chips have an input for a temperature sensor made me think that there is some failure mode in charging that causes high temperatures and during which it's a good idea to shut down charging.  I'm not knowledgeable beyond that.  I'm trying to work out what bad things might happen if I omit the temperature sensor.

  • 0 in reply to Charles Gervasi
    Genius 3290 points

    Thanks for the clarification.

    It is important to monitor the temperature during charging.

    If you charge a Li Ion cell at too low a temp (below -10degC) you can damage the cell and permanently lose capacity in the cell.

    On the high end, it is typically not a safety issue, but it will accelerate the aging of the cell.