I've always wondered whether the Mac consumes energy when it's in sleep mode (my laptop can last a damn long time in sleep mode), so I want to know whether the 8 hours it's in sleep is comparable to the energy required to start it up.
My MacBook draws about 30 watts on boot up which takes about a minute. That's 30watts/minute of power. When it's in sleep and plugged in it draws 2 watts. For it to consume 30 watts it would take 15 minutes of sleep!
However, the power brick is inefficient, especially at low power, so this is hardly a fair comparison.
I'll see if I can come up with a better test of how much power my MacBook uses when it's sleeping on its battery and post back.
I suppose this brings up the whole debate in relation to "How green is the Apple in Apple?" Steve Jobs goes to some length to outline Apples green credentials here, www.apple.com/hotnews/agreenerapple/
In relation to the amount of energy a mac uses in its various modes www.apple.com/environment/energyefficiency/http://www.apple.com/environment/energyefficiency/
First off I'm new to Eden Bee so sorry for initially writing in stories rather than Q&A.
Now this is all still back of an envelope stuff, but I've put some work into this.
Firstly I downloaded minibatterylogger to monitor my battery levels. I noted my battery charge level in milli amp hours and then closed the lid for 100 minutes. On opening the lid I plugged back in and noted how long it took to return to the pre sleep charge level, it was 4 minutes and my mains power meter told me my MacBook was pulling 34 watts.
Now I had to wait a couple hours for my MacBook to fully charge (I tested at 75%).
When the charging was over I could see that my MacBook was ticking over at 15 watts.
So, the re-charge drew 19 watts for 4 minutes which is 76 watts and thus the 100 minutes in stand by used 76 watts.
Next what does boot up take?
Well my MacBook boots up on 26 seconds (which is a lot quicker than I expected) and I kept a keen eye on my mains meter during boot up. It peeked at 30 watts, but not for long, most of the time it was in the 15 to 22 watts range. A conservative average for this would be 24 watts which equates to 10 watts of power.
So start up takes 10 watts power before you can use it - Ten minutes of sleep takes 7.6 watts. By my calculations if I'm leaving my MacBook for more than 13 minutes I'll use less power turning of than putting it to sleep!
