Apple iPhone 5S users take note – even when your phone battery dies, the handset can still track your every move.

This is because when a battery dies, the phone keeps a small amount of power in reserve, meaning its low-energy chip can carry on collecting data from built-in motion sensors.

It can’t track location, however, but it can reveal how many steps a user takes, or establish whether a phone was still being carried around when used with select, third-party apps.

The feature was discovered by Reddit user Glarznak while travelling abroad.

After four days without charge, Glarznak found that when he turned his iPhone back on, the number of steps he had taken during those four days had been recorded on a pedometer app he had installed.

Glarznak wrote: ‘I frequently use Argus [fitness app] to track my steps since it takes advantage of the M7 chip built into the phone.

‘Once I got back from my vacation, and charged the phone, I was surprised to see that Argus displayed a number of steps for the four days that my phone was dead.

‘I’m both incredibly impressed and slightly terrified.’

Apple handsets, as well as other devices, traditionally keep a reserve of power – even when the phone shuts down – in order to maintain certain services and help it boot up when put on charge again.

For example, when a phone battery reaches zero on the display there is, on average, around 5 per cent battery left. .. see more

source: dailymail UK