Is there a way to rename "Remaining" to "Apple Juice Remaining"?
You want to change line 92 of the xml version of  /System/Library/CoreServices/Menu Extras/Battery.menu/Contents/Resources/English.lproj/Localizable.strings:


Make a copy of the strings file:

cp /System/Library/CoreServices/Menu\ Extras/Battery.menu/Contents/Resources/\
English.lproj/Localizable.strings ~/Desktop

Convert the binary strings file to xml:

plutil -convert xml1 ~/Desktop/Localizable.strings

Edit line 92 (Yosemite) of the file now on the desktop with your favourite text editor:


Convert the xml strings file back to binary:

plutil -convert binary1 ~/Desktop/Localizable.strings

Back up your existing file! If you mess up, this will let you reverse your changes by removing -bak from the file name.

sudo mv /System/Library/CoreServices/Menu\ Extras/Battery.menu/Contents/Resources/\
English.lproj/Localizable.strings /System/Library/CoreServices/Menu\ Extras/\
Battery.menu/Contents/Resources/English.lproj/Localizable.strings-bak

Overwrite the old file with the new:

sudo mv ~/Desktop/Localizable.strings /System/Library/CoreServices/Menu\ Extras/\
Battery.menu/Contents/Resources/English.lproj/





Result: