I have a mid-2015 MacBook Pro running High Sierra. Except when I'm traveling, I always use it in clamshell mode and connected to power. I rarely put it to sleep (I have Energy Saver set to just put the display to sleep).

On July 21 I noticed that the light on the power connector had gone to amber, but Energy Saver said that the battery was fully charged. However, coconutBattery said the battery was at 95%.

Today I noticed that the lightning bolt was no longer showing on the battery status in the menu bar, and when I click on it it says "Battery is not charging". Energy Saver says that the battery is at 97%, but coconutBattery says 81%. Here's its full report:

Current Charge 6347 mAh
Full Charge Capacity 7092 mAh
Design Capacity 8755 mAh
Manufacture date 2018-03-07
Cycle Count 31
MacOS battery status Good
Battery temperature 37.0°C
Charging with 0 Watts
Power adapter Connected

Does this look like a problem with the battery, power adapter, or SMC?


I reset the SMC, and at first it seemed like the problem was solved. The battery item in the menu bar said it was charging, and eventually said it was fully charged, and the power adapter changed to green. At that time coconutBattery said:

Current Charge 7030 mAh
Full Charge Capacity 7030 mAh
Design Capacity 8755 mAh

But while I was posting an answer to the question, it changed to:

Current Charge 6766 mAh
Full Charge Capacity 7029 mAh
Design Capacity 8755 mAh

The adapter light is still green.


The adapter light changed to amber a couple of days after the above update, and the menu says "Battery is not charging". Energy Saver says that the battery is at 98%, but coconutBattery says 76%. Its history viewer shows:

Date                Health%     Charge Capacity Cycles
2021-08-01 17:21:28 80.29697    7030    8755    31
2021-08-02 09:10:45 80.28555    7029    8755    31  
2021-08-03 10:01:09 80.01142    7005    8755    31
2021-08-06 00:53:35 77.72701    6805    8755    31
2021-08-09 13:33:42 76.02513    6656    8755    31

And System Information says this in the Power tab:

Battery Information:

  Model Information:
      Serial Number:    C018104BAG5FWLMF1
      Manufacturer: DP
      Device Name:  bq20z451
      Pack Lot Code:    0
      PCB Lot Code: 0
      Firmware Version: 702
      Hardware Revision:    1
      Cell Revision:    3241

  Charge Information:
      Charge Remaining (mAh):   5959
      Fully Charged:    No
      Charging: No
      Full Charge Capacity (mAh):   6623
      Health Information:
      Cycle Count:  31
      Condition:    Normal
      Battery Installed:    Yes
      Amperage (mA):    0
      Voltage (mV): 12252

AC Charger Information:

  Connected:    Yes
  ID:   0x0100
  Wattage (W):  85
  Revision: 0x0000
  Family:   0x00ba
  Serial Number:    0x00f277bf
  Charging: No

So what should I look for to understand why the battery is draining instead of charging?

I tried putting the computer to sleep for a few hours yesterday, it didn't help.

  • 2
    Could you not just eliminate it being a SMC issue by resetting SMC? Jul 30, 2021 at 23:29
  • Probably, just don't want to go through that whole procedure if it doesn't seem like an SMC issue. I hate rebooting.
    – Barmar
    Jul 30, 2021 at 23:48
  • It’s really hard to tell if it’s the SMC without resetting the SMC. I’d really recommend you save all your files and do an SMC reset. Jul 31, 2021 at 2:30
  • 1
    Your reply suggests you haven't even tried a reboot, so probably start with that. Jul 31, 2021 at 11:12
  • I actually rebooted a week ago for a different (some programs were hanging).
    – Barmar
    Jul 31, 2021 at 11:14

2 Answers 2


You need to get the battery replaced. Even if it isn't flagging the 'Needs Servicing' flag, it's six years old, draining rapidly, with a diminished capacity.

80% of original capacity is Apple's threshold to replace the battery. If it's under warranty, they'll do it for free. If not (and yours isn't), you'll have to pay.

If the capacity is much higher, they'll tell you it's fine and to come back when it's lost a bit more!

It's around $200, but the good news is that because of the design, they actually replace the entire 'top half' - the keyboard, trackpad and upper case. So it's a pretty good investment to prolong the life of your Mac.

  • I used Option-Click on the battery menu, it says "Condition: Normal".
    – Barmar
    Aug 10, 2021 at 9:45
  • 1
    But I'll take my Mac to the Genius Bar and have them check it out.
    – Barmar
    Aug 10, 2021 at 9:46
  • I took it to the Genius Bar, they said the battery was bad (and it now says "Service Battery" in all the utilities). But it would have taken nearly a week to replace it, and my boss said he couldn't have me offline for that long, so I'm getting a new M1 MacBook instead. But I'm accepting this answer.
    – Barmar
    Aug 20, 2021 at 14:49

Your battery is rather old ( ~ 3.5 years ) and had a rather very small cycle count ( ~ 30 ). Then its high level of charge slowly decreased.

I suggest you to fully discharge your battery in one pass. Unplug your Mac, and let it go to the point where it will make a forced shutdown or switch on hybernate mode. See pmset -g | grep hibernate. When you reach the 5 % level, take care to save any open file, and even better, close any open application.

Next fully charge it in one pass and to its max charge reachable. Check again the output of coconutBattery. If its current charge is pretty near 80% again, then you should planify your battery replacement.

You don't have to tinker with the SMC ( this is rather a religious trick from bad guys working in support and who respect procedures rather than analyzing problems ). Many users who apply this reset of the SMC conclude it fixed their problem when in fact in the cases I throughly checked it is just the reboot of MacOS which fixed it.

  • 1
    I recall that this procedure of fully draining the battery was recommended on older Macs (I did it a few times in the 2000's), but it wasn't recommended on newer ones. Also, the Mac won't run in clamshell mode with power disconnected.
    – Barmar
    Aug 2, 2021 at 13:50
  • 1
    RE: "You don't have to tinker with the SMC ( this is rather a religious trick from bad guys working in support and who respect procedures rather than analyzing problems )." -- Apple states in one of its support documents "Resetting the System Management Controller (SMC) can resolve certain issues related to power, batteries, fans and other features.", (emphasis mine), from How to reset the SMC of your Mac Aug 2, 2021 at 13:53
  • I am sorry to have to inform you than on many different Macs, Apple support advised me to reset the SMC and facts prooved that this tinkering was just a procedure and didn't fix in any approaching way the original problem ( which in fact was a bad computation of remaining battery charge upon exit of sleeping ). This bug stay unfixed for more than 4 ≠ versions of MacOS.
    – dan
    Aug 2, 2021 at 13:57
  • I even get to a point where an expert at Apple aknowledged that they don't have internally any tool to diagnose if an SMC is faulty and they follow this stupid procedure because of the lack of such a tool.
    – dan
    Aug 2, 2021 at 14:00
  • 1
    Say what you want, it's taken with a grain of salt as I have over the years found for a fact that resetting SMC has resolved an issue at that time. I'm not saying it's a cure all, but as I had it work first hand I have to believe there is validity in the process. Just like a full shutdown and startup can and does resolve some issues. You have to start the troubleshooting process somewhere. Your info about draining and recharging the battery is a valid and known procedure, however, it could have been presented without the biased opinion of your last paragraph! So no +1 until its removed. Aug 2, 2021 at 14:59

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