I have a Macbook Pro from late 2011. it shuts down when the battery percentage is anywhere from 20-45%. Everything that I've been reading online says that the battery is dying and needs to be replaced, but I replaced the battery less than six months ago, and to my knowledge, they're supposed to last upwards of 4 years.

  • a) Click on the battery icon and tell us what 'Condition' MacOS says it's in. b) The temperature (either of the actual battery, or mobo in general) may be high. Install a temperature monitor and tell us the temperature when charging. Very high temperatures damage battery health. c) Battery lifetime estimates (or number of charge cycles) are estimates and vary enormously. Was your replacement battery new or used? Was it Apple, Apple-certified third-party or non-certified? Which manufacturer? How many charge cycles did it have when installed? CoconutBattery is a good monitor program for those. – smci Sep 3 '17 at 0:32
  • Also, the obvious general caveats apply about excessive apps, trying rebooting in Safe Mode (no apps) and comparing power consumption with normal mode. Even a malware scan. Also please tell us what MacOS version, and was that a clean install or upgrade (those matter), and did the weird power behavior manifest after a upgrade or a certain date? – smci Sep 3 '17 at 0:33
  • Though you may have only bought the battery 6 months ago, it could be a) defective, or b)NOS or New Old Stock meaning it sat around for several years. If you purchase a new battery, get one with an 18 month warranty so you can avoid issues like this. – Allan Sep 3 '17 at 12:26
  • May sound too obvious, but in my case, the issue was simply that I hadn't done a hard reboot in several weeks. So I can confirm it can be as simple as that, for other folks experiencing this. – Jason Denney Sep 23 '18 at 20:50

The first thing I'd recommend you try is resetting your MBP's System Management Controller (SMC).

Resetting the SMC

To reset the SMC on your particular MBP follow these steps:

  1. Shut down your MBP
  2. Unplug the power cable from your Mac
  3. For 10 seconds, press and hold at the same time the shiftcontroloption keys (on the left side of the built-in keyboard) and the power button
  4. After 10 seconds let go of all keys and the power button
  5. Plug in the power cable
  6. Turn your MBP back on with the power button

Once you've done this I'd fully charge your MBP and then test to see if the same behaviour returns.

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