MacBook and saving energy

MacBook is my favourite laptop I’ve ever owned. I use it daily in my school and I carry it from lecture to lecture and I like it’s sleep functionality – I can just close the cover, carry it to other place, open the cover up and it’s ready to roll in a matter of seconds – including my ssh connections and everything.

The only problem I got, is the battery usage when the MacBook is in sleep mode. As said, the sleep mode (power saving mode 3) means that the ram is copied into a file in the filesystem and the ram contents is kept up using battery current. If battery level goes too low, the power is turned off and the ram contents will be restored from the disk on next startup. If I keep my MacBook on sleep for a few days, the battery is empty. I tried to research for ways to keep MacBook in the power saving mode 3, but to schedule total poweroff on midnight, so that the battery current would be saved. This would result on longer startup time on the first poweron on next morning, but I believe the current savings would benefit much from it. So far, I haven’t found any ways to implement this. If you are interested to learn more about the different power saving modes, check out this excelent blog entry about them, which covers the pmset utility which can be used to alter different power saving settings.

On this research, I found out about MiniBatteryLogger which displays battery data in almost realtime. You can also obtain this info from About This Mac -> More Info -> Power -> Amperage (mA). This is the current current which moves to the battery (if it’s positive) or from the battery (if it’s negative). After a quick research, I found out that dimming the display brightness down to almost minimum saves over 250mW of energy! This results in almost 45 minutes more usage time when running on battery power! Now I can easily try out different strategies to save battery power and thus resulting greater uptime. :)

One thought on “MacBook and saving energy

  1. There is a script available which will modify mac so that it will goto hibernate mode. This will in practice mean that the memory content will be saved to a file and mac will shutdown. If you press the poweron/off button the content of the file will be read, and the state of the mac is restored to the one before the hibernate mode was activated.

    I am yet to find ways to extend the battery life – i will use that tip to reduce display brightness, thanks for sharing :)


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