The battery power is the amount of electrical energy stored in the battery. Mobile devices are powered by rechargeable lithium-ion (Li-ion) or lithium polymer (Li-poly) batteries. The power capacity of the battery has a direct impact on the usage time. A battery with a higher capacity will store more energy and thus provide more electric power for your device so you will be able to use it for a longer time without having to recharge it.
The battery power or battery capacity is measured in milliampere-hours (mAh), a unit that indicates how much electric power can be used over time. A battery with more mAh translates into longer battery life. The average phone has around 3,500mAh, which usually means it can last for at least a few hours of intense usage (playing games or making video calls).
Besides the usage patterns, the draining of the battery capacity is also influenced by many other parameters. If the device has a large screen size, like most flagship phones nowadays, and a highly performant chipset, it will use more power. Most phones last for at least half a day when being used intensely. There are also a lot of methods to save battery power, like setting the device to flight mode or turning off applications that run in the background and consume a lot of energy. For this reason, the battery power is one of the main concerns when choosing a new phone, tablet, or any other mobile device.
The current record for the phone with the highest battery capacity is held by Energizer Power Max P18K Pop, which has an astounding 18,000mAh battery. This means it can last for up to five days when used in normal conditions. A mid-range tablet has a battery power of approximately 6,000mAh. Tablets typically have larger batteries than phones because they have larger screens and consume more power.