Awaking from sleep - battery loss

[ajgrant]

I left my MBP in sleep mode with the lid shut for about 2 hours or so. Left it at 36%, when I opened it and started to use it again, it went down to 31% within a minute or two.

Is this just the battery being slow to update, or could it suggest an issue?

 

[yjchua95]

I left my MBP in sleep mode with the lid shut for about 2 hours or so. Left it at 36%, when I opened it and started to use it again, it went down to 31% within a minute or two.

Is this just the battery being slow to update, or could it suggest an issue?

It's normal. During sleep, the laptop will drain some battery to preserve the contents in the RAM.

If it runs out of battery during sleep, the MBP will automatically write the RAM's contents into the hard drive before going into hibernate.