These are some informations about the Lithium-ion button battery LIR2032:

  1. Voltage: 3.6 V.

  2. Capacity 35 mAh.

So its full energy is \$3.6 \times 35m \times 3600\ \text s=453.6 \ \text J\$

But if this battery is used in a device,which minimum working voltage is 3 V, I mean when the voltage of battery is less than 3 V, the device won't work.

So the real supplied energy for this device is \$(3.6-3) \times 35m \times 3600 \ \text s=75.6 \ \text J\$, not \$453.6 \ \text J \$, right?


1 Answer 1


Here's the charge/discharge curves for that battery:enter image description here

It doesn't sag to 3.0V until 100% of the capacity is discharged. Note you won't get that in real life, but you'll likely get 90% while it's capacity is still fresh. Here's the full datasheet. Also, don't forget to include parasitic voltage drops.

I'm not sure what you're hoping to gain with any energy calculations.

  • \$\begingroup\$ so this figure show me this battery can only supply some device to about 3.2V(100%)?so the whole energy of this battery to other device is \$(3.6-3.2) \times 35m \times 3600s=50.4\$ ? \$\endgroup\$
    – XM551
    Aug 30, 2019 at 3:31
  • \$\begingroup\$ No I don't think you want to subtract the voltages. A good estimate is just to use 3.6V since it's in the ~middle of the profile. Also not sure where you are getting 35m. The calculation would be current x time to get charge, then charge times voltage for energy. So 2.35mAh is 2.35mA for 1 hour multiplied by 3.6volts to get energy. If you want a more accurate calculation based on the changing voltage, you'd need to integrate the voltage over the entire profile, which would be a pain to express mathematically. \$\endgroup\$
    – AJbotic
    Aug 30, 2019 at 3:47
  • \$\begingroup\$ oh!this figure means that if the battery 0.5C to discharge,then when the battery is dead for some device,we can find that the voltage of battery is about 3.2V? \$\endgroup\$
    – XM551
    Aug 30, 2019 at 4:21
  • 1
    \$\begingroup\$ @AJbotic: The battery capacity is 35 mAh. OP was using a numbered list without spacing between the numbers and the items on the list so it looked like 2.35 mAh. Fixed. Note to OP: spacing and punctuation are important! There should be a space after every punctuation mark and none before it. There should also be a space between numbers and units as in "3 apples" and not "3apples" so "35 mAh" rather than "35mAh". (See SI standards for more.) \$\endgroup\$
    – Transistor
    Aug 30, 2019 at 6:15
  • 1
    \$\begingroup\$ @XM551, 0.5C is the charge and discharge rate for the respective plots. The horizontal axis, I'm guessing is a misprint and should say "Rated Capacity (%)", not "Rate Capacity(%)". It sounds like you are having a fundamental misunderstanding of how to read the plot. Here are some links... mpoweruk.com/performance.htm ti.com/lit/an/snva533/snva533.pdf \$\endgroup\$
    – AJbotic
    Sep 3, 2019 at 16:40

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