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> Li-ion Battery How To Calculate Capacity
teaman
Posted: December 19, 2011 04:29 am
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Hello,

I have a quick question. If I have a 3.7V li-ion battery rated at 1600mAh and I use it to power a circuit that requires 3.7V and 200mA, does this mean a fully charged battery will last for 1600/200= 8 hours?

Thanks smile.gif
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MikeGyver
Posted: December 19, 2011 04:57 am
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1600mAh is the capacity. This means it will deliver 1.6amps for 1 hour (unless a specific dischage rate is given).
You are correct, and technically at a lower discharge rate it will deliver slightly more power due to less I^2R losses, etc.

BTW, battery capacity ratings are often very inaccurate and sometimes flat out lies (especially in the li-ion world). Usually only high quality, expensive cells live up to their rating.
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teaman
Posted: December 19, 2011 08:08 am
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QUOTE (MikeGyver @ December 19, 2011 04:57 am)
1600mAh is the capacity. This means it will deliver 1.6amps for 1 hour (unless a specific dischage rate is given).
You are correct, and technically at a lower discharge rate it will deliver slightly more power due to less I^2R losses, etc.

BTW, battery capacity ratings are often very inaccurate and sometimes flat out lies (especially in the li-ion world). Usually only high quality, expensive cells live up to their rating.

Great, thank you for your fast answer.

And advice headed wink.gif
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colin55
Posted: December 20, 2011 01:29 pm
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You will not get 8 hours out of the battery. The rating is generally determined on a 24 hour basis.
The current will drop after 3 or 4 hours, due to the terminal voltage.
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