High temperature rise with 18650 battery.

  • I've checked through this forum site and Google but haven't found an answer, hence the post.

    I have a number of 18650 batteries harvested from an old laptop battery, some new 18650 Li-Ion (LiFePO4) batteries and a couple of Li(NiCoMn)O2 batteries commonly used in solar lights that have been powering NodeMCU's and Wemos D1 Minis for some time now. They are typically 2600mAh capacity.

    We are developing a series of remote sensors with SiPy/FiPy and Pysense/Expansion Board V3.1. When I tried to use those batteries the temperature of the boards and modules climbed dramatically, exceeding 50C in about 10 - 15 seconds before I pulled the plug....didn't want to leave it any longer.

    I've seen 18650 batteries used in other projects with Pycom boards etc and wonder if I'm doing something wrong.

    Any assistance appreciated.

  • Thanks jcaron...

    Polarity was correct coming out of the battery based on the red/black colour of the wires going to the JST connector, but wrong going into the Pycom board...all good now system is working well.

    Thanks again.

  • @jcaron It's fryday! Also sounds like reverse polarity to me.

  • @SiMoS-IoT are you sure the polarity is correct? There is no standard for polarity on that connector, and many batteries (mostly those used for drones and other RC devices) have the reverse polarity.

    Have you successfully used other batteries with the devices? Are the devices still functional? Where they actually working when you connected those batteries?

    Do the batteries come with an integrated protection circuit?

  • I have the 18650 battery in a battery holder that has a JST connector. The connection has the correct polarity. This is inserted into the JST connector on the Pysense board.

    The voltage of the batteries are nominally 3.7V but I checked then with a multimeter when they were fully charged and they were 4.1 volts.

    I checked the temperature of the board with a ir temperature gun just near the JST's connection to the board...when the SiPy module is attached to the board, the SiPy module's temperature also rises very quickly.

  • @SiMoS-IoT How did you connect the batteries?
    What is the battery voltage?
    How did you take the temperature?
    Which part of the board showed the high temperature?

Log in to reply

Pycom on Twitter