Max pulse discharge current on batteries

Discussion in 'General Electronics Chat' started by Midge, Jun 8, 2015.

  1. Midge

    Thread Starter New Member

    Jun 4, 2015
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    1
    I'm looking for a relatively small rechargeable battery to power a small timer circuit.

    An LIR2032 *looks* ideal for my purpose on the face of it (typical rating 40mAh), but I'm trying to understand exactly what the spec means by "max pulse discharge current" - which is typically given as 70 or 75mA for this type of battery.

    I guess this means it can sustain a short duration current discharge significantly greater than it's continuously rated discharge current, but surely there should be time/cycle information quoted? If not, is there any rule of thumb?

    In my case, my circuit draws <1mA when sleeping so no issue there, but every 1-5 minutes (adjustable), it switches on a mobile phone vibration motor and a small buzzer for a period of 5 seconds (total current 70mA).

    Thanks!
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    1,605
    Got a link to the data sheet? All Yahoo seems to offer are distributors and not a manufacturer's link.
     
  3. Midge

    Thread Starter New Member

    Jun 4, 2015
    13
    1
    Hi Ernie - I think the battery I am using to test with is made by these folks but I can't be certain as it isn't marked. http://www.eunicell.com. I can't find a datasheet on their site.

    Most of the LIR2032s have the same sort of spec but I've found very few datasheets and none which fully answer my question e.g.

    www.powerstream.com/p/Lir2032.pdf

    Some sites like this one just list a max discharge value of 2C which I assume is 2x the nominal capacity?

    http://www.weamax.com/products-sear...lithium-rechargeable-button-battery-3-6v.html

    Midge.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    The Powerstream data sheet simply states "3.6 Max. Discharge Current 70mA." Later it does call out test 6.9 where the device is tested with this current "Until final discharge voltage" so it seems safe enough to draw such a current on an intermittant basis.

    What this does to your total capacity I could not guess.

    How much less than 1mA is the sleep current? 1mA by itself will drain a 40mAH battery in 40 hours all by itself.
     
    Midge likes this.
  5. Midge

    Thread Starter New Member

    Jun 4, 2015
    13
    1
    It's a 7555 timer circuit and my meter reckons 0.1mA for the circuit as a whole, so it won't make any practical difference to the overall operating time, which I'm still testing. The theory says about 30 hours with 5 minute intervals, down to about 7 hours at 1 minute.

    I guess this pattern of use might ultimately hasten the battery's demise too, but only time will tell.....

    Thanks for the advice.
     
    ErnieM likes this.
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