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.
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:
- Shut down your MBP
- Unplug the power cable from your Mac
- 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
- After 10 seconds let go of all keys and the power button
- Plug in the power cable
- 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.