What does it mean when you unplug your power from your Mac book and the computer shuts off?

at a guess yes. A way you can test it is ti cycle the battert thru a charge / discharge cycle 3 times, this may take several days. If it doesn't hold a charrge for at least 5 hours pending on usage then your up for a new battery pack. When you get you new pack charge it fully then let it discharge fully, this will extend the life of a battery pack. Short term charges, if the pack is not Lithium or Nickle Hydroxide will get a ghost charge in them reducing the life of the pack. If you can't afford top of the range battery pack carry a charged spare with you.

attempt a sparkling battery first. while a battery won't carry a fee ninety 9% of the time it is because of the fact the battery is not any good. If it is below a 12 months previous call Apple and function them deliver you a sparkling one. it would be lined below guarantee.