Posting this here because I couldn't find anything on ehMac, Apple support or the Apple discussions. Ended up with an Applecare call.

Problem: after a superb debut performance resulting in my no longer having to take my charger on day trips, my MBP's battery steadily degraded. Running it down to hibernation and giving it a full recharge didn't do the trick. I was down to 3.5 hours with erratic jumps of 1/2 hour in either direction the norm.

Solution: reset the PMU (of course) but the Apple site pages have not been updated for the new models or they are carefully hidden! Here are the steps:

1) Connect a power adapter

2) Hold LEFT (?!) shift, alt, ctrl + power button for one second

3) Reboot with the Power button

4) Err... that's it - no need to cycle/run down the battery. I now have a 'new' MBP!

PS: My starting figures were a battery capacity of 6500 mVolts and 80 cycles, in other words a reasonably healthy battery, it has now reset to 12500 mVolts

:)

That sounds too easy to possibly work. That is amazing. Does it work on a two year old MBP too?

Think you may have missed this KB article:

Apple Portables: Resetting the System Management Controller (SMC) (http://support.apple.com/kb/HT1411) describes the same sequence of steps (though notes that you need to start with the MBP OFF - and hold the keys for 5 seconds, not just one) ;)

I wish this would work with a 2 year old MBP, but I think my battery is half shot, no matter what I do. I just bought a new one, but haven't installed it yet.

Yeah, and you reset the SMC, not PMU. Newer Macs no longer have a PMU (Power Management Unit).

And like the poster above me posted, if the battery really is worn down, resetting the SMC will not resolve the issue. A mechanically drained and worn out battery cannot be repaired by system resets. The OP's battery isn't worn down much; it just seemed to have stopped functioning like it should, and thus a SMC reset resolved the problem.

and hold the keys for 5 seconds, not just one) ;)


Whoops, that's not quite right either. You wait five seconds, not hold the key for five seconds:

MacBook Air and MacBook Pro (Late 2008 and later)

If the computer is on, turn it off by choosing Shutdown from the Apple () menu.

Connect the power adapter to a working power source.

On the built-in keyboard, press (left) Shift-Control-Option along with the power button once.

Wait 5 seconds and press the power button to start the computer.

Note: You must use the keys on the left side of the built-in keyboard.

so has anyone actually tested this? o.O

so has anyone actually tested this? o.O

Why bother? Just read post number 4, two above yours.

Why bother? Just read post number 4, two above yours.

i dun understand someone translate for me :P

i dun understand someone translate for me :P

I meant read the post below from Lars, a certified Apple tech. It does NOT work if your battery is low:

Yeah, and you reset the SMC, not PMU. Newer Macs no longer have a PMU (Power Management Unit).

And like the poster above me posted, if the battery really is worn down, resetting the SMC will not resolve the issue. A mechanically drained and worn out battery cannot be repaired by system resets. The OP's battery isn't worn down much; it just seemed to have stopped functioning like it should, and thus a SMC reset resolved the problem.