Battery life is a perennial problem for smartphone owners. While our handsets have become faster and more powerful over the years, smartphone batteries often last less than a day under heavy use, or even moderate use after a few months.

The lithium-ion battery has been around for more than two decades, and hasn't fundamentally changed since Sony started producing them in 1991. And despite lots of effort being put into replacements, these batteries are likely to be with us for many more years.

Here's what you need to know about your smartphone's battery.

Do I need to charge my phone when I first get it?

No. Earlier battery types like nickel cadmium had a "memory effect" that meant batteries would maintain a certain capacity based on how they had been charged and discharged. This meant that electronics products often came with advice to charge them fully and keep them plugged in for hours before using them.

However, with modern lithium-ion batteries most people agree that there is no such effect and the batteries are more reliable. A smartphone is fine to run out of the box without "priming" it beforehand.

For the same reason, you don't need to calibrate your smartphone by running the battery all the way down. While this used to be the case, Apple and others no longer recommend it.