Can a 15MBP battery drain with a 60W charger?

Discussion in 'MacBook Pro' started by mbenji, Apr 25, 2019.

  1. mbenji, Apr 25, 2019
    Last edited: Apr 25, 2019

    mbenji macrumors member


    Aug 27, 2016

    Can the battery drain/decrease in this scenario? I have a 2016 touch bar MBP.

    I have the apple HDMI adapter and it is 55-60W, any test I can do to check if I can bash the MBP enough to drain/decrease the battery?

    Thanks :)
  2. leman macrumors G3

    Oct 14, 2008
    Under full load, the MBP can draw more than 90 watts, so yes, it can.
  3. mbenji thread starter macrumors member


    Aug 27, 2016
  4. gnasher729 macrumors P6


    Nov 25, 2005
    It usually doesn't. I had my MacBook Pro running Handbrake, while using a 60W charger, and after more than 24 hours the battery was uncharged. Turned of WiFi and turned the brightness completely down, and it very slowly recovered. So unless you have CPU usage at 700% to 800% all the time, you'll be fine.

    BTW. Nothing goes wrong. It doesn't hurt your MacBook at all. All that happens is when the battery goes below 5%, the MacBook slows down to about half speed, saving energy, until the battery is up to 10% again, and then it speeds up again, battery drains again, and so on forever.
  5. leman macrumors G3

    Oct 14, 2008
    The CPU TDP is 50Watts, so running it at 100% (I mean "real" 100%), will put your system power consumption somewhere around 60-70Watts, depending on brightness, storage activity etc. So its not unrealistic to run heavy CPU processing with just a 60W adapter. Not so much if you are using the GPU though.
  6. currahee2100, Apr 25, 2019
    Last edited: Apr 25, 2019

    currahee2100 macrumors regular

    Feb 9, 2009
    TDP is not the entire story though. They can use waaaay more than TDP. It's hard because it's variable.

    The only real way to measure consumption I think is by using an electricity usage monitor, like kill a watt. And even then you'd have to test a stressful scenario.

    My quad core 2018 13" however, will charge on a 45W power delivery battery bank, at normal usage.
  7. leman macrumors G3

    Oct 14, 2008
    Only for a few seconds though (I've seen my i9 pull over 90 Watts for a second or two). In sustained operation under heavy load however, the system is designed to run close to the TDP. In other words, the average CPU power draw (over a reasonable time frame) should not exceed the TDP.
  8. xeux macrumors regular


    Jul 19, 2007
    Phoenix, AZ
    Yeah, typically anytime the GPU is being used or the CPU is under stress it will exceed what the 60w can provide.
  9. kohlson macrumors 68000

    Apr 23, 2010
    Several years ago I was on vacation, but had my work computer - a 15-in MBP. I forgot the charger, but my wife had her 13-in MBA charger. 45 watts, I think. My strategy was to use this charger to top up the battery while closed/hibernating. But a couple of times the battery was low while I needed to work. Once was Exchange indexing itself. The other was the virtual meeting room app. Both these were 100% of a core, and the power draw was quite high. The power supply got quite warm/hot. The power adapter never really worked after we returned home, and I had to replace it.

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8 April 25, 2019