Li-ion battery discharge

  • Suppose that a lithium-polymer battery is connected to a PyCom Expansion board (or PySense, or whatever) battery port, and it is desired that the system keeps running for an extended period on battery power, then the user plugs in power to the USB port, recharges the battery, and repeats the cycle.

    If the system keeps running for a long time, until the battery is discharged, is the lithium battery protected against an unhealthy level of discharge?

    Is this protection provided by the battery management hardware on the Pycom board, or is it entirely dependent on the PCM (protection circuit module) built inside the LiPo cell?

    Even if the system is allowed to discharge the battery indefinitely, I assume that the battery PCM will protect the battery and cut it off at some voltage like 2.7-3.0V.

    And could I assume that the battery charger IC will happily detect a valid battery and charge it from that discharged state?

    I'd like discharging and charging of an integrated lithium battery to "just work", without any extra technical steps or attention, where the battery is enclosed in a box and the end user is expected to only plug the system into a USB power supply every couple of days and repeat this process indefinitely, cycling the battery, without any real technical experitse from the user.

    So I guess my questions are:

    • Will this behaviour "just work" on a PyCom Expansion Board, or PySense, and SiPy or LoPy board
    • If not, what can be improved to implement this behaviour, where the battery remains healthy and viable?

  • @robert-hh said in Li-ion battery discharge:


    All of our boards use the same bq24040 circuit, therefore it is recommended to use batteries with a PCM to protect the battery from over discharge

  • @luke There is little published about the expansion boards and other shields internals. At least, for an older version of the expansion board schematics have been published. They show the bq24040 as charging device, but no circuit of preventing a battery from beeing drained completely. So that has to be done by the battery's PCM. Besides that, you can hook up the battery and let it run from that, and if USB is present, it will be charged.

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