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# Help needed with microphone battery consumption

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#### neazoi

Hi I would like to build the electret circuit shown in the datasheet and feed it with a standard CR2032 battery.

I need a little help with the numbers. How much time of continuous operation should I expect from the microphone with this battery?
A rough estimation based on the numbers.

Thank you

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• CR2032.pdf
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• EM258-EM158N.pdf
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Hi,

as with any battery and any circuit...

There is
* battery capacity (given in Ah or mAh) and
Bot values should be given in the respective datasheet

Then battery capacity is current x time ... thus the units are: A x h = Ah
now if you have capacity and current then rearrange the formula and get
time = capacity / current.

Klaus

### neazoi

Points: 2
There are some numbers that confuse me that is why I need the help. These numbers are specified under conditions.
For example
Nominal capacity(15kOhmCont.,2.0 Vcut-off) 265 mAh

Hi,

a battery is no ideal "energy storage". Thus the datasheet says:
Delivered capacity is dependent on the applied load,
operating temperature and cut-off voltage. Please refer
to the charts and discharge data shown for examples of
the energy/service life that the battery will provide for

In the chart you see different "load resistances" and how the output voltage and the expectable capacity behaves.

What exactly is unclear?

Klaus

If you take the capacity curves, and choosing a tolerable cutoff V,
look at curve that is equiv to that @ mic current, that then gives you
overall capacity, excluding T effects and long term chemistry degradation.

Its crude given slope of discharge curve non zero, but decent approximation.

Then divide that capacity by mic current and you have your answer. You can modify
for T using capacity vs T graph, but that correction does not seem to be huge.....

Regards, Dana.

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