Why does my MBP say “Not charging” when plugged in?

Question

I have the latest 2011 Macbook Pro. Sometimes I notice that even when I'm plugged in, the battery status says "Not charging" even when I unplug it and the battery is at 35%. Why isn't my MBP charging?

This can be very annoying if I want to unplug and take my laptop somewhere.

Edit: This mainly seems to happen if my laptop is under load. I had some flash thing going and I could hear the fan. Once I closed flash it started charging again.

Answer 1

Some obvious causes:

1. Need to wait 30 to 60 seconds for the SMC to read the battery and decide what to do
2. check for pencil lead/debris on the mac end of the magsafe
3. check for pins stuck down on the magsafe cord end of things
4. The SMC needs to be reset on the Mac
5. The battery, all adapter or charging circuitry itself is faulty or detecting something that causes a pause and the mac might need service. (This is exactly what your mac will do if it needs an 85 watt adapter but you've somehow gotten your "friend's" 65 watt adapter - if your adapter isn't putting out enough power, the mac can only run and not support the CPU/GPU load as well as the charging circuitry. Similarly, if the battery is drawing more than designed, the mac will prefer to run than charge and tells you this in the not charging message.)

Due to the way batteries work, they can be out of range at only a certain voltage range so initially it will be good until you reach that one point where the voltage drops too fast and shows aging or a problem with the cells.

Do a calibration run at your earliest convenience and think about a visit to the genius bar or other service desk if the problem continues. Take your wall adapter with you when you go as it can be checked with the mac together.

Answer 2

I've noticed it with ours too. Try completely unplugging the charger from both the MBP and the wall outlet. Besides that, just make sure that when you plug your computer is plugged in, the green/amber light is on.

Answer 3

We had the same issue with our new 17" MBP at work. We contacted Apple and they said this was normal behavior. Apparently there are certain situations (e.g. during high CPU/GPU usage) in which the MBP cannot draw enough power form the power adapter, so it must also draw from the battery.

Answer 4

I saw this behavior within the first few weeks of getting my Mid 2010 MBP 13". It seemed like a simple jiggle of the charger would fix it most of the times. If that didn't work, unplugging/plugging it back in to the laptop always seemed to do the job. I'm not exactly sure what caused it in my situation, but I haven't seen it since then (Nov 2010).