Why is it that something as small as a phone can have great battery life yet Laptops with a bigger footprint can only last 6-8 hours?
In: Technology
When your phone screen goes off, your phone quickly goes into a really-low-power mode that consumes very little battery. It is able to do this because the OS and hardware was intentionally designed for it. The OS aggressively puts apps into sleep or background mode, and the phone only wakes up occasionally to do background tasks and tries to stay in that really-low-power mode as long as possible.
If you kept the phone screen on and watched videos or played games on it, the battery life would be comparable to a laptop.
The laptop, on the other hand, has its screen on almost all the time because it was designed for that. (If your laptop’s screen went off every 30 seconds to a minute, you would throw it against a wall.) While it is doing work, it is not in a really-low-power state, and hence will not achieve phenomenal battery life. Some laptop processors are able to go into a similar really-low-power mode (in Intel processors, this is called the [S0ix state](https://software.intel.com/en-us/vtune-amplifier-help-s0ix-states)).
But the OSes running on most laptops, and the processors running in most laptops, were never really designed to optimise for battery life so aggressively. It is difficult for an OS to encounter conditions favourable to enter really-low-power state: it will seldom encounter moments when the processor is truly idle, and most software running on laptops do not take kindly to suddenly having their tasks halted. You wouldn’t really want Photoshop suddenly pausing the filter it is applying when you turn to chat with a friend, or Excel to stop calculating your PivotTable while you take a toilet break.
So laptops need a much bigger battery to have the same battery life.
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