Need reassurance about powersaving

Discussion in 'MacBook Pro' started by EuroMac, Jan 12, 2013.

  1. EuroMac, Jan 12, 2013
    Last edited: Jan 12, 2013

    EuroMac macrumors newbie

    Jan 12, 2013
    My 15" Retina MBP lives in clamshell mode, hooked up to a large monitor and a large Wacom touch tablet and I don't need to use the laptop's screen or battery most of the time - merely to unplug and carry it about with me occasionally...

    That's all working great, except that I'm not sure that I am doing the right thing with power management!

    I would prefer not to 'shut down' the computer every night if possible. Last night, for instance, I let the computer go to sleep and didn't worry about the green light on the magsafe being on. I know the battery won't keep charging after this green light indicates it's full.

    However, when I was lying in bed, I suddenly became worried it might use a lot of electricity if I literally leave it that way every night. Like mobile phone power chargers notoriously keep sucking energy even when your phone is not connected to them? So I went up to my studio and switched off the switch by the wall plug, thinking I would just switch it on in the morning and then hit a key or the mouse and wake the Mac up.

    When I touched the mouse this morning, the Mac did wake up instantly, everything going to plan so far. But then I noticed battery power was down from 100% to 94%. I checked the power settings and see that it's set to "powernap" and also to wake up for wifi.. so realised of course that it did have systematic tasks to carry out while sleeping and that when I cut off the mains it became obliged to use the battery to do them, hence the drop.


    There are a number of difficulties I have with this. Firstly, I don't want the computer to be doing anything during the night. Second, I don't think it would be good to continually and repetitively use my battery that little bit then top it up. I have therefore switched off powernap and the other nocturnal stuff.

    Of course, now I am wondering whether the laptop will still do some things when sleeping and still use the battery a little. Would it be better to simply leave that green light on, leave it permanently on mains, even when sleeping, to avoid this nibbling of battery power and not worry about it using a bit of electricity just because it's plugged in - or would it use significant amount of electricity merely because it's plugged in like that and ultimately be better to just shut the computer down and then switch off the wall plug too!

    Remember: I'm not asking whether night time activity on the MBP uses a lot of power. I know it doesn't. I am asking whether keeping it permanently plugged in overnight uses a lot of electricity.

    Thoughts would be appreciated and please note I have already read through Apple's issued advice.

  2. Ploki macrumors 68040

    Jan 21, 2008
    afaik powernap is enabled only when running on power supply.

    some battery drain is normal for extended sleep periods because the computer doesn't hibernate (>> write RAM contents to disk, wake up, read contents back in to RAm, boot) but "sleep", so the RAM needs to be powered if you want "instant wake".

    You could set it to "hibernate" but it will take some time for it to wake up (depending on the disk-speed and ram size)

    It's not big deal if you loose some charge during the night, it will keep the electrons in the battery going.
  3. Inconsequential macrumors 68000

    Sep 12, 2007
    The answer is no.

    Powernap is probably <5W, so for 10 hours asleep <50W is nothing.

    Although I do beg the question why on earth you bought an rMBP if you use it in Clamshell mode all the time!? :p
  4. EuroMac thread starter macrumors newbie

    Jan 12, 2013
    @Ploki, actually I have separate settings for 'Enable Power Nap while plugged into a power adapter' and 'Enable Power Nap while on battery power' - so I have unchecked both.

    @Concorde Rules, I'm a filmmaker so the laptop does go into the field, but it's nice to have a desktop and laptop that are the one device rather than needing two separate machines

    I'm thinking that I should probably just leave it plugged into mains all the time, except when I unplug it and carry it around which I know is good for the electrons in the battery anyway...
  5. Ploki macrumors 68040

    Jan 21, 2008
    Obviously i don't know because I still haven't received mine :(

    That's been my workflow the last 4 years, I'll keep it with the Retina.
  6. Rhyalus macrumors 6502


    Mar 4, 2011
    It sounds like deep sleep (hibernate mode) would be a good choice for you. I use it at night, but during the day I use conventional sleep. I use the "deep sleep" app you can search for on the web to go into hibernate mode at will.

    Hibernate mode is especially nice if you have an SSD. Restoring for this deep sleep only takes a couple of seconds.

    In general, you do not use a lot of electricity when you go into sleep mode, but if you are hyper interested, check out my suggestion above. Memory is committed to the hard drive / SSD (space used is the same as the amount of RAM that you have).

  7. Queen6 macrumors 604


    Dec 11, 2008
    Flying over the rainforest at dawn - Priceless
    Clarity; you need to exercise the battery or it will loose life, this is a fact. As OSX has AC power and battery power profiles you simply need to set them up for your needs. On AC my Mac`s don't sleep, on battery i leave it to Apples default values, when i am done working i just pull the power cord, if the system needs to process data for a extended period of time i leave the power connected, if not i pull the cord....
  8. EuroMac thread starter macrumors newbie

    Jan 12, 2013
    Really? That's good to know! I kind of, intuitively, believe that Apple have already taken all of this into account... and that if I leave the MBP sitting there plugged in permanently, unplugging it every few weeks and taking it out or downstairs or whatever, the machine will be perfectly healthy. But I guess more old fashioned experiences with other computers, ahem, and devices and design in general has left a bit of fear and concern behind.

    This computer is what I always thought a computer should be.

    I particularly love the solid state aspect of much of the internals - feels a lot more sensible to me.
  9. Ploki macrumors 68040

    Jan 21, 2008
    I've been on the fence for quite a while... I hope I won't regret getting it over cMBP.
  10. EuroMac thread starter macrumors newbie

    Jan 12, 2013
    There seems to be one outstanding issue with this, however - and that is what to do with my 4gb Seagate drive which is attached to the Macbook... every time I wake up the computer I am getting an impertinent complaint that I didn't properly remove the device! I had been just leaving it switched on too, but suppose it's too much to expect the third party machine to share all these aforementioned sleep patterns? LOL :D
  11. EuroMac thread starter macrumors newbie

    Jan 12, 2013
    Update: this in fact has not worked out at all...

    Sometimes the mbpr won't wake up and the clamshell has to be opened and closed, i.e. it may be necessary to open and close the laptop at least some of the time that you want the activate it for use on other screen.

Share This Page