The Just Say Yes Challenge: MacBook Battery Life Test

I’ve been reading all of the drama regarding battery life on the new 2016 MacBook Pros, at the same time I was doing a bunch of legacy machine software testing. During this I realized that many of my old MacBooks had dead batteries that needed replacing. So I replaced them, and as a way of conditioning them, I ran this simple test:

  • boot machine
  • System Preferences / Energy Saver/ set Screen sleep and system sleep to “Never”
  • set screen brightness to 100%
  • open N terminal windows (where N = the number of hyper threads your CPU has)
  • in each terminal execute this command: yes > /dev/null
  • time the system until it goes to sleep due to low battery.

I tested about 10 machines spanning 8 years of MacBook(Pro)s from 2006 thru 2012, from a 32-bit Core Duo (2 core) all the way through a 8-hyperthread Core i7, and was surprised to find that almost all of them would run this test for about the same amount of time: 60 to 75 minutes.

Like all benchmarks, this is artificial: it only exercises the CPU. Other parts (GPU, network, hard drive/ssd, etc.) are ignored. Also, it’s important to note that we are measuring Time, not Work - an i7 with 8 hyperThreads is doing much more computation than a lowly Core Duo even if both only mange to stay alive an hour.

If anyone out there has 2014 or later MacBook Pros, it would be great to hear your results!