How to make your phone’s battery last longer

Phones don't die, their batteries do

The batteries in most phones die after a couple of years.  This can make a perfectly usuable phone useless without an expensive battery replacement. Here’s what you can do to extend their life

What's going on?

When a phone manufacturer builds a phone they’ve got a decision to make: do they make the battery last a long time, but not hold so much charge, or do they opt for maximum charge at the expense of battery life?

We all know what they choose, and it also lets them convince us to buy new phones every couple of years rather than opt for an expensive battery replacement.

Stressed out

The life of a battery is determined by the stress it’s put under.  More stress = shorter life.  Most of the stress comes from the design of the charger circuit, but you can’t hack this (which is why the SoundBucket circuit is designed for longer battery life), but you can alter your behaviour to extend the battery life.

As a note, the batteries rarely fail completely, but as they get used and overcharged, they just can’t hold as much charge anymore, so run out in a jiffy!

Tip 1: Don't let the battery run flat

The maximum stress occurs when a battery is discharged to nearly flat, fully charged to 100% and this process is repeated.

The solution is simple – don’t let your battery run to below about 20%.  As soon as it reaches this level, recharge it

If you can, recharge more often.  If you recharge when your phone is at 40%, you’ll nearly double the battery life over letting it run out.

Tip2: Don't charge to the top

The other end of the stress occurs when a battery is fully charged.  Phone try and ram more charge into a battery by charging them to a higher voltage.  En route to this, the battery voltage rises slowly as it charges until about 80% of the charge, after this point it starts to get voltage stressed.

The solution is to charge to about 80% to 90% of maximum, to avoid the higher voltage charger stress.

Tip 3: Don't charge when it's really hot, or really cold

Batteries hate extreme temperatures, so always charge them at normal room temperature. Charging and operating at high temperatures is as bad as heavy charge and discharge cycles.
For this reason, if you phone is getting hot, remove any protective plastic cover (plastic is a heat insulator) for a while to let the phone cool down.

Tip 4: Don't use fast chargers when you don't have to

Fast chargers essentially dump more charge into a battery, so they charge quicker.  This heats them up, which again causes stress.  As a norm, don’t use fast chargers all the time and turn them off when they get to that 80% charged figure.

Summary

Your phone is a great bit of kit, use it as normal and don’t worry, but if you can charge it as we’ve suggested, your battery should last longer than normal :)

Lithium ion (Li-ion) batteries are charged using a fairly sophisticated process. They are first charged by a constant current, which makes their voltage rise.  Fast chargers dump more current into them during this phase. Once they reach a threshold voltage, the charger then changes the charge mechanism to constant voltage and the charging current slowly reduces to zero. Fast chargers offer no benefit here.
To fully charge the battery, the charger needs to perform both phases of charge. Typically the second stage takes as long as the first and contributes about 10 to 15% of the batteries capacity. However being held at this high charge voltage damages the battery.
For industries where battery life is important, this charge voltage is kept deliberately low, and this can make the battery last up to 10x longer than a phone type charger.  Against this, the battery will only ever hold 70% of the charge it could do.