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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?

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5 Answers 5

Probably SSD should consume less power but extra ram module uses more power and also generate more heat and it may result to higher fan speed . And in some case over heating the battery will reduce capacity

I think you should also check battery life cycle from applications-->utilities-->systeminfo if it is higher than 300 it is some how acceptable to lose capacity .

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It's not the battery capacity itself though. Something is eating power and I'm not sure what. When this started happening I bought a brand new battery, but since then I have digged deeper and realised it's the power draw rather than capacity that is the root of the problem. –  Ben Dec 10 '12 at 20:14
Also, I had read that RAM consumes only a very small amount of extra power. I have put my original 2GB back in and the problem perists, so I can't see how it can be that. –  Ben Dec 10 '12 at 20:38

All the things you did could easily decrease the battery life. Opening your case could have introduced dusts -- causing the computer to run hotter with less efficient fans. Your hardware may not be connect properly.

Overall though I suspect an SMC issue. Reset your battery cycle by running the computer until it dies then research how to reset your mac's SMC.

If all else fails you can try getting apple to fix it.

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I've tried quite a few SMC resets. Would an SMC issue cause the reported mA consumption to be inflated, or would it instead report the battery life wrongly? –  Ben Dec 10 '12 at 20:40
Interesting point about heat though. Question edited to add fan speed. –  Ben Dec 10 '12 at 20:44
BTW, how do I 'reset my battery cycle'? –  Ben Dec 10 '12 at 20:47
Edited for battery info -- Basically make sure the battery is completely and totally drained. This re-syncs the battery state with the computer. –  November Dec 11 '12 at 19:49
Got it. I tried that (letting it run down, go into suspended state and then left it two more hours so it completely ran the battery down) but it didn't make any difference. I've reset the PMC several times too (before and after the battery reset) but no joy... –  Ben Dec 12 '12 at 18:15

I'm hoping you didn't knock something or shock your MLB with static while installing the drive. This can really damage the computer and cause weird behavior. It might also explain the extra power drain.

Are you following Apple's guidelines (http://www.apple.com/batteries/notebooks.html)? You also have to calibrate new batteries by draining them, then charging them to full for two weeks. Never leave it plugged in for long periods during the two weeks. After that, make sure you are continuing this practice at least once a month. You have to exercise batteries like a muscle. They need to know when they are empty and when they are full.

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I'm hoping that too! :) I did the calibration twice now. Don't think it's the battery itself, anyway. –  Ben Dec 17 '12 at 19:28
Sorry for the late reply. Batteries are tricky to test. I know that Apple only has a pass/fail test and if the battery isn't failing, there's nothing much that they will do about it. It definitely seems to be a hardware issue at this point. It wouldn't hurt to have a Genius poke around. Have them run a full hardware diagnostics on it. –  pacothelovetaco Jan 3 '13 at 17:37

You can try checking your battery capacity. There are tools for that like:




If your battery capacity is close to its design capacity than there is some problem with actual energy usage. If the battery capacity is low, (4/6 -> 66%) of the maximum than your battery is the problem after all.

Hope this helps.

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Quite simply, 'Mountain Lion' like 'Lion' before it, runs many more background processes.. that's exactly why it uses more power. the SSD does take a little less power.

Depending on your geekness: If you're running Snow Leopard (or any OS) you may want to enable 'Trim' support (wear levelling) for your Mac, Google for an app called 'Trim Enabler'

In 'Lion' and 'Mountain Lion', an app called 'Mountain Lion tweaks' lets you make sure TRIM is enabled in the OS for your SSD.

If you're a Unix Geek and have full backups you can delete, disable and remove unused and unwanted system services and daemons from OS X, whichever version you're using. a tool called 'Lingon' will allow you to disable any and all the system services you want. It also will render your OSx installation unbootable, un-log-into-able and you will need to reinstall OSX over the top again to get the system to boot again.. Snow Leopard runs less crap in the background, as did Leopard etc...

I know this by experience, and have been hacking on Linux for nearly 18 years and do keep good backups, so am not afraid to reinstall when over-tweaking the OS.

If you have no OS (particularly Linux, BSD or Unix) experience you might not want to bother too tweaking much.. and go back to Snow Leopard, as you WILL end up reinstalling the OS ... (backups are critical) Good Luck & if you're not sure, dont do it and blame me !

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I've already downgraded back to Snow Leopard (clean install) and my power drain is still higher than it used to be. I'm assuming something got knocked or similar when I opened my MB to put the new hard-drive & memory in. Putting my old RAM and hard drive back in doesn't fix it either you see. –  Ben Mar 25 '13 at 13:57

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