This seemed to happen after I did several things at once (all of which I have since reversed in trying to track this down):

  1. installed a (Crucial M4) SSD drive (replacing my old SATA 5400 RPM drive),
  2. upgraded from 2GB RAM to 4GB, and
  3. upgraded to Mountain Lion (from Snow Leopard)

For weeks I've been trying to track down what the problem could be. I've read all sorts of things about Mountain Lion using more power and various conflicting things on the Crucial forums about whether or not their SSDs consume more or less power (SSDs are generally advertised as being less power-hungry but there are a few conflicting reports!).

Anyway, I'm now back to my old SATA drive, my original 2 GB RAM and a completely clean install of Snow Leopard. But I still have a reduced battery life and I can't figure out why.

Where I'm at now is that the milliAmps consumed by my MacBook when it is pretty much completely idle (i.e. 1-3% CPU usage in Activity Monitor, All Processes) it is consuming about

925 mA (according to System Profiler)

It fluctuates, but often goes up above 1400 mA and never lower than 750 mA. I never paid attention to this value before but I know two things:

  1. I used to get > 6 hours battery life in normal usage (emails, browsing) and now I get < 4.
  2. My friend's MacBook idles at around 450 mA.

My fan speed is 1800rpm during this normal usage.

Any ideas how I can solve this? Is there perhaps anything else I can reset? It feels like a hardware issue.

Alternatively, is there a way to see the number of mA being drawn by the various components of my MacBook?

  • +1 For all the work you've done trying to get this figured out already. I hope you will receive some help on this. Dec 10, 2012 at 20:42
  • Interesting. My Macbook (late '08) is using ~ 1600 mA when I just checked. Course, my battery lasts only about an hour with a cycle count of 483, and health of 80%. Dec 10, 2012 at 20:54
  • 2
    Have you tried to reset the SMC (or SMU, PMU, depending how old your Mac is)? I would give it a try. Maybe when you changed the hardware there have been some changes which haven't been redone. support.apple.com/kb/HT3964?viewlocale=en_EN&locale=en_EN
    – cyphorious
    Dec 11, 2012 at 12:22
  • Yes, I've tried that but no discernable difference.
    – Ben
    Dec 11, 2012 at 19:35
  • 1
    How many cycles does the battery have? Is the battery health reported as ok? (also in system profiler)
    – Agos
    Dec 12, 2012 at 10:04

1 Answer 1


I would look at top -u to see if there are active processes that should not be there.

I would look at the system profile: Apple => About This Mac => More Info... => System Report => Power and see what it says about the battery... In particular the Condition and Cycle Count.

To compare two Macs, be sure the brightness is the same and both are spinning down their disks.

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