Question: Ask yourself, why don't we have a smartphone with a battery life of 7 days?





Note:

This article is meant for normal users and not for power users (the flagshippers) who use their phone like a desktop and prefer maximum performance even if it means charging their phone every time they find a charging port.





Introduction:

I personally have a Moto Z Play that runs for 3 days straight on a single charge with a total screen on time (SOT) of 15 hours (5 hours SOT per day).



It can be further understood that in a single day, my phone's screen and processing were active for 5 hours and the doze (sleep with sync) mode was active for (24-5)=19 hours. This doze time is 3.8 times the 5 hours of SOT per day.





This is attained on a 5.5 inch 1080p display with a battery of 3510 mah and a snapdragon 625 processor (14 nm manufacturing).



Software Changes/Tweaks (to get such an amazing battery life):









Further Technical Changes (required to attain a week long battery life):

The display is downgraded to an ergonomic 4.7inch 720p display (has the same ppi as an Iphone). The battery capacity is increased to 5000mah. An increase of 20% in the overall hardware operating efficiency is applied:

A.) As per regular technological advances in 2 years which has already been achieved in the latest series of Snapdragon hardware, and

B.) As per the decrease in processing of screen elements due to the display bein down-scaled to 60% (720p) of its original resolution (1080p). No increase in overall software operating efficiency is assumed as any increase in efficiency gets used by the increase in processing load as software evolves to be heavier with time.

Intermediate Calculations:

The new screen on time will be:

15*(1080/720)*(5000/3510)*1.2=~38.5 hours.

This is equivalent to 5.5 hours of screen on time for all 7 days of the week! But for most *average* users, the average daily SOT is 4 hours. So we have an extra SOT of [38.5 hours - (4 hours*7 days)]=10.5 hours on our hands (remember this number it will come in handy later) Additionally, the doze/sleep mode time is increased to:

19 hours*3*(5000/3510)*1.2=~97.5 hours. However, our desired doze/sleep mode time is 20 hours*7=140 hours

Thus it can be seen that our doze/sleep mode time is short by (140 hours - 97.5 hours)=42.5 hours This shortcoming can be achieved by now using the extra 10.46 hours of SOT we have on our hands.

Since we already know that 1 hour of SOT equals 3.8 hours of sleep/doze,

10.5 hours of SOT =~40 hours. Thus the doze/sleep mode time is further increased to: 97.5 hours+40 hours= 137.5 hours (this is 2,5 hours short of the desired 140 hours).



Final Results:

28 hours of screen on time = 4 hours*7 days 137.5 hours (2.5 hours short of the required 140 hours) of doze (sleep with sync) time 6.895 days of battery life (1.5% short of the required 7 days)





Now, I believe, you can imagine only charging your phone once a week!









Some things that still may be difficult to accept:

4 hours of SOT. 20% increase in total hardware efficiency. I only used Wi-Fi for internet and not an LTE connection. I didn't play any games or poorly coded apps (like Facebook's official app). Weight of phone - the weight of your phone will actually stay the same as we are ditching at least ~20% of the weight of the phone by making its screen smaller thus resulting in lesser size (thus weight) of components being used. This decrease in weight of the phone's body will be balanced by the increase in the weight of the battery by ~30%.





Lastly..



If you think that this phone would never actually get you a battery life of 7 days even though you are an *average* user because there are some things you can't make a compromise on, remember that those issues can be addressed by:

Increasing the battery capacity even further or Downgrading the Snapdragon processor from the 600 series to one from 400 series.