If you have an older Mac and the older version of the Battery.menu app backed up (or downloaded from a trustful source), you can replace the new crippled Battery.menu with the former one that shows the Remaining time.
Inspired by this article, but in my case, I had to do everything in the Recovery mode in order to make it work.
They also link the old menu version if you trust them. I fortunately had my own backup.
Approach in general:
- Get the previous version of Battery.menu
- Reboot into Recovery mode
- disable System Integrity Protection
- swap Battery.menu apps
- enable System Integrity Protection and reboot
- open this guide in your phone to keep it on eyes
- get the old Battery.menu e. g. to ~
- Reboot to Recovery mode (Command-R while start-up)
- Run Menu: Utilities > Terminal:
# csrutil disable
- Trigger Recovery mode again (Command-R while start-up)
- backup replace Battery.menu again in Menu: Utilities > Terminal:
# cd /System/Library/CoreServices/Menu\ Extras/
# cp -R Battery.menu Battery.menu.backup
# cp -R ~/Battery.menu .
# csrutil enable
- Double-check the System Integrity Protection is really enabled after rebooting in Terminal:
# csrutil status
This last step is really worth double-checking, because forgetting it would mean a serious vulnerability of your Mac.