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May I know whether I am properly converting from mAs to mAh. If wrong please guide for the proper method. I am taking standby current to show my calculation.

The chip is working on a 3.3 V supply and its standby current is 0.00085 mA. For one day the chip will be active only for 4.24 seconds. Rest of the time it will be in standby mode.

My calculation for standby mode energy consumption is given below.

Standby mode current = 0.00085 mA (1)

Standby mode time/Duration in a day = 86400-4.24 = 86395.76 Seconds (2)

Multiplying(1) & (2) = 73.44 mAs (3)

For converting mAs to mAh, I am dividing (3)/3600, that is 73.44 / 3600 and the final value is 0,020 mAh

May I know is this correct or not?
I need to find the battery spec for my system that is why I'm doing this.

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    \$\begingroup\$ Confused, you also need to include the current required during the 4.24 seconds it is operating, assuming the 4.24 seconds also includes start-up-from-sleep time. The stand-by current and the supply rail means about 240 Joules per day for stand-by. But some more will be needed during that 4.24 seconds of operation, too, when considering a battery (+ capacitor?) question. \$\endgroup\$ Commented Oct 8 at 18:06
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    \$\begingroup\$ Confused, In particular, if you are using that 4.24 seconds to operate a transmitter where significant power may be involved.... \$\endgroup\$ Commented Oct 8 at 18:09
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    \$\begingroup\$ Didn't you learn in school that you need to take units into account? Doing so you cannot "discalculate". Anyway, yes, the calculation is right, but not specific to electrical engineering. \$\endgroup\$ Commented Oct 8 at 18:40
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    \$\begingroup\$ the coversion to seconds makes no sense, not for 4 seconds in a day ... instead do 0.00085 mA × 24 \$\endgroup\$ Commented Oct 8 at 18:59
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    \$\begingroup\$ @Confused Do you have any fluency with dimensional analysis, at all? Also, for proper sizing all of the details are needed. This includes things like the maximum duration awake, the maximum current draw when awake, etc. Averages are also useful, of course. But you need to accommodate the worst case situation, too. You don't get to rely on averages. You have to handle the peak cases. Also, many devices support more than one sleep mode. So thoughtful design can buy a lot where sloppy thinking makes for much poorer performance. \$\endgroup\$ Commented Oct 8 at 19:49

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