Confusing question: How does our cellphone knows the percentage of battery left???

How does our phone make out that this much % of battery is left, any method you know, pls share, no answers found till now please....

2 Answers

71
Vivek @ Born this Way ·

A typical cell phone battery is the lithium-ion type. It is fully charged when the battery open circuit voltage is around 4 volts. As energy is used the voltage drops off towards around 3.5 volts. This 0.5 volt change corresponds to going from fully charged 100% to around 20%. Somewhere just below 3.5 volts the unit will reach “low battery” and turn off automatically. The state-of-charge monitor circuit of the cell phone simply measures the battery voltage and indicates to the user by means of a display of “percent charge remaining”, often with a bar graph.

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1
Gurtej Singh ·

Thanks Vivek, asked many people and searched the web, couldn't find a proper, sourced answer. Your's sounds correct.

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