I have always been one of those people who live by the ABC motto when it comes to cell phones and other electronic devices with lithium ion batteries. I never want to be without battery juice when I need it most. With the somewhat recent Watch announcement and critical (and rightly so) reviews of the battery life strategy Apple appears to have chosen, I became decidedly curious about the battery life of my iPhone 6. I wasn't really sure if I could make it through the day on my phone because I have never tried.

My first assumption in this experiment was the phone would lose charge sometime around 2 or 3pm. I'm no slacker when it comes to app usage. I have 524 applications in total and several running in the background pinging geolocation data and serving push notifications. Here is a list of the apps I have running in the background that use the GPS functionality-some continuously and others intermittently through the day:

I use my phone constantly during the day for work email, PDF review, and consuming social media via Paper, Tweetbot, and Instagram. There's not a period of time I don't have my phone in my hand or in front of me on a desk or conference room table. I think you would agree that I fall in the heavy user category, maybe more than most since my iPhone is always passively working in the background plus my direct use.

For purposes of observing my battery usage I decided to follow a few rules during the experiment:

The phone would be unplugged at 8am from the charger.
Battery data points would be observed starting at 8am, and every two hours there after. The last data point of the day would be 6 pm to allow for any necessary recharging for evening activities. This is for mainly when the evening activities would have me away from the home or office.
The phone would not be charged before 6 unless it went dead from use.
Any unusually usage would be noted in my observation comments.

Here is the data from a typical week of use:

When you read the chart below, the data is plotted with % Charge on the y-axis and Time of day on the x-axis. Of course the phone is fully charged at 100% at 8am every day. I then took data points in 2 hour increments hoping to see some trends for weekdays, certain periods of the day, and weekdays versus weekends.

For weekdays, the battery drops on average 10% between 8am and 10am. Another 17% is used between 10am and 12pm, 18% between 12pm and 2pm, and so on. Just by looking at these stats, it's obvious that the heaviest use hours are between 10am and 2pm. Another heavy use time is 4pm to 6pm. The difference between these periods and the others can be attributed to the following:

Most meetings occur in the hours right before and after lunch. This involves more phone usage to coordinate, exchange emails, text other participants during meetings rather than interrupt the discussion with sidebar topics, downloading files, and other activities of this nature.
Lunch is a high use time due to social media consumption, messaging, email, and non-wifi data usage.
The end of the day is similar to the lunch hour, lots of catching up: social interactions, audio streaming via Bluetooth in the car, and last minute emails. Also coordinating the family activities for the evening is done during this time of day.

For drain rates by two hour periods germane to each day, see the table below:

This table displays the data in a different context. The cells reflect values of the data points relative to the previous data point. Put another way you can see what percentage of charge is consumed in each 2 hour period of time by day. The plot of battery data points above gives an idea of the general Remaining Battery Charge, but this chart shows the magnitude of use for any two hour period with the various colors corresponding to specific days. Although the there are variations between days as I might expect, the overall average tells me much about which hours I might be more affected by battery drain.

There are some things that might not be immediately apparent when looking at the data. For example, if I had a 3pm flight to catch, I might want to grab a little charge during lunch and while waiting at the gate so that I would have a decent charge remaining after landing. This mid-day charge would help compensate for the higher drain rates during the lunch hour period. Furthermore, it indicates that the times of lowest battery drain are also better hours to charge. A period of low battery drain is indicative of lower phone use as compared to other periods and charging during that time is going to mean less interference with the use of my phone than at other periods. Think of this as battery use pressure. When the bar is high (high drain), the phone is under high use during that time, or high pressure so to speak. Conversely, when the bar is low, the phone isn't being used as much, therefore, less battery drain occurring. This is a perfect time for a short boost charge.

Since I did not include data points through full battery discharge, I extrapolated the data at an average drain rate of 14% per two hour period. This yields an estimated full discharge time of day of approximately 9:30pm to 10pm at night. Since the evening drain rates are likely to be higher, I would expect a full discharge to occur by 9:30 pm on average.

Conclusion

The [iPhone 6][1] battery lasted much longer than I anticipated. I think the average person has no need to charge their phone during the day and doesn't need to worry about the ABC mantra. Of course this will change as the battery ages and OS updates tax the hardware beyond what it was originally intended to handle. I intend to capture this data periodically over the life of my iPhone 6 and see how it performs over time. I think 3 months would be a good interval to see how the battery performs over time. I'll check back soon with results from the second run.

[1]: My iPhone 6 is the 128 GB model. iOS 8.1 was used during the capture of data. This experiment was performed in November.

Update 2015-01-12

Jason Snell writes about the life expectancy of iOS devices and posts some charts of iPhone and iPad. His conclusion is that Apple is trying to provide 10 +/- hours of battery life. My data is on the + side, but only slightly. I think he is on to something. We might not see more than 10 hours of battery life unless it's a device like the 6+, which seems to be to be an outlier at this point.

iPhone 6 Battery

Conclusion