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Thread: RTC battery for T3.2

  1. #1

    RTC battery for T3.2

    What are the recommended RTC batteries for the Teensy 3.2? CR2032? Something else?

    How long would a CR2032 last? (I'm just looking for an approximate, ballpark figure)

  2. #2
    Senior Member+ manitou's Avatar
    Join Date
    Jan 2013
    CR2032 is 240mah. CR2032 is used only when power is off T3.2. T3.2 datasheet says 0.67 ua for RTC with no T3.2. Others measure 1.6ua. so that's about 17 years

  3. #3
    Thanks, I got it. I think I'm not going to verify that figure ( ) but I have a feeling that with heat and self-discharge factored in, it's likely to be significantly less than 17 years.

    But I guess I can probably expect a CR2032 last for about 5 years or so.

    Of a possible other option, does anyone know how complicated or costly is a circuit that would charge a LIR2032?

  4. #4
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Most CR2032s have a "shelf life" spec in the 5 to 10 year range. Usually those specs are worst case scenarios based on higher temperatures, so they may not be an issue if the battery is kept at room temperature or in a cold environment.

    Then again, the self discharge may play a factor, for less than the 17 years you might expect from only the capacity rating.

    Here's one graph that really explains the situation pretty well.

    Click image for larger version. 

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