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When my MacBook gets below 1% battery life I believe the CPU slows down. The battery indicator states I have 10 minutes left but those are the longest 10 minutes in the laptop cycle. Is there a way to slow down the CPU so I can get longer battery life at the cost of lower performance?

Well, Walnut wanted proof that the CPU was being throttled. So I went to sun spider performance test here ran the test at critical performance, critical performance while plugged in, calculating battery life, full power on battery and full power plugged in. Here are the results +/- 15ms on average:

Battery at full plugged in:          215.5ms  
Battery at full not plugged in:      203.5ms  
Battery at critical not plugged in:  555.0ms
Battery at critical plugged in:      230.0ms
Battery unknown not plugged in:      748.8ms

The results seem to indicate that OSX runs full CPU power when battery is full or it is plugged in. When the battery is in critical it runs half as fast (takes twice as long). When the battery status is unknown it runs one third as fast (takes three times as long).

To put it another way if the CPU is rated at 1Ghz then when battery is critical it's running at 500Mhz. When battery is unknown (and critical?) it runs at 250Mhz.

So I was right Walnut! TAKE THAT! IN YOUR FACE! ...I'm joking. You're alright. More people should ask for proof.

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You dont see to many people asking how to slow their computer down... –  Keltari May 20 at 20:58
    
Did you ever consider that it might not actually be warning you when the battery is at 1%? My guess is that there is reserve power and when you get the '1% battery' notification, you actually have more. –  Wutnaut May 20 at 21:14
    
@Wutnaut - I have considered that. I'll have to run some tests but I'm fairly certain it slows down. It is noticeably slower. In previous versions of OSX there was an option to choose better performance over battery life or vice versa in the Energy Saver preference. So at one time it was possible for the user to change this option manually. And now I believe the OS is making that choice for me at 1% or 10% battery life. –  1.21 gigawatts May 22 at 22:50
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I appreciate the effort to verify this behavior. I'm not very familiar with Macs and haven't experienced it. The only thing that's bothering me, 12.22 gagawuts: my handle isn't WALNUT! NO MORE HELP FOR YOU! –  Wutnaut May 23 at 15:05

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