Benchmarks Need to Represent Actual Usage

Posted by Matt Birchler
— 2 min read

DXOMARK: Always-on Display: How Does It Affect Battery Life?

The results of our battery tests revealed that autonomy was largely impacted by this always-on screen feature, draining the battery about 4 times faster! The battery will last roughly 100 hours in idle when activating the feature, instead of 400 if the feature is deactivated.

Wow, so the always-on screen drains my phone 4x quicker than normal! I'm turning that off immediately.

But wait…those raw numbers are a bit out there, right? The battery lasted 400 hours with the always-on screen off? But my phone lasts like a day or two at most, so what's the deal?

Well, this test was done with the phones in airplane mode, all wireless connections were disabled, and the phones were never used. In other words, they've eliminated all other battery drains from the phone and left just the screen. This is a perfect example of a bad benchmark, in my opinion, as it gives you a comparison that feels scientific, but tells you nothing of value.

If you told me that my iPhone that lasts 5 days (122 hours) could last nearly 3 weeks (466 hours) if I turned off the always-on display, I might consider doing that, but that's not what this actually say at all. There are so many things on your phone that chew up battery life, and the screen, even in always-on mode is a tiny part of that.

Think about it this way, when eliminating basically every other battery suck from the iPhone, the always-on display drained the battery about 0.82% per hour vs 0.22% per hour with the screen disabled. If we assume:

  • You wake up at 6AM and take your phone off the charger
  • You never charge throughout the day
  • You go to bed at 10PM and put your phone on the charger

In those 16 hours…

  • 4 hours screen on time
  • 2 hours in pocket
  • 10 hours on desk with always-on enabled
  • Battery is at 30% by the end of the day

Stick with me here, but this means in 16 hours, your phone used 70% of its capacity. Your usage will vary, but I think this is at least in the ballpark for a lot of people, and it similar to my average use of my phone.

If we use the DXOMARK benchmarks to figure out how much of that is due to the always-on screen, we can look at the 10 hours of always-on time and the drain rates they had in their testing. The math is pretty simple here:

  • At 0.82% per hour, we can say up to 8.2% of the battery drain was from the always-on display.
  • We also know the phone will drain 0.22% per hour with the always-on display off and nothing else happening, so 2.2% was unavoidable.
  • Therefore, 8.2-2.2 is about 6% of the 70% drained over the course of a day was due to the always-on mode.

So in short, if your battery is down to 30% at the end of the day, you might be able to have it at 36% if you turned off the always-on mode. That's something, and if you don't find the always-on screen helpful (DXOMARK's survey showed people nearly perfectly split on this question), then turning this off will help you get a bit more life out of your phone. However, I think presenting the data as if your phone drains 4x quicker with the always-on screen enabled is an unhelpful benchmark for how these products are actually used.