I have an ancient macbook that a few months ago started gradually losing the ability to hold a charge (or so it seemed). I've noticed for a long while that it doesn't last nearly as long as my sister's newer macbook. Maybe an hour-hour and a half and then it dies. But a few months ago the battery symbol at the top of the computer started saying less and less and less battery charge even if I had it plugged in 24/7. It finally got down to being at about 6% all the time and if I would accidentally unplug it, it would die right away. It stayed like that for a while and I was going to go get the battery replaced bu just ever got around to it. Then a few weeks ago I noticed it was back up to 37%. Then a few days later I noticed it was at 70% and so on until now where it will go to 100% and then hold a battery for at least an hour or two again. What in the world is going on?