I've noticed a significant battery drain on my MacBook Air (2015 model, 8GB RAM, 512GB SSD) when I use the command `pmset -a hibernatemode=25`. My understanding is that this mode should write the memory contents to the SSD and completely cut power to the machine, unlike `pmset -a hibernatemode=3`, which keeps some power running. I closed the lid with a 45% battery and when I checked two days later, it was down to 18%. Can anyone explain why this is happening? I've gone through the Apple documentation, and it seems like mode 25 should prevent any battery drain while hibernated.
2 Answers
Actually, I have to disagree. When you hibernate on Linux or older Windows versions, the system writes RAM to disk, then powers off completely, and there's no battery drain. From what I read about macOS, mode 25 should also behave similarly. The fact that you have a new battery should help, but age can still affect how power is managed.
Keep in mind that hibernation isn’t the same as fully powering off the laptop. Older hardware like yours may not handle power management as efficiently as newer models. Don't forget, you're working with an 11-year-old system, and wear could have affected its performance.
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