Question

A lithium-ion battery of a GSM mobile phone has a voltage of 3.6 V and an electrical amount of 900 mAh. How long is the battery life in talk mode when the phone draws 300 mA?

Answer 1

We can find the battery life from the formula:

$$Battery\ Life=\dfrac{Battery\ Capacity}{Load\ Current},$$ $$Battery\ Life=\dfrac{900\cdot10^{-3}\ Ah}{300\cdot10^{-3}\ A}=3\ h.$$