2

I have had a new battery in my mid 2012 15" macbook pro running 10.11.6

The battery health as monitored through a battery health app downloaded from the mac app store has been deteriorating ever since i installed it and after about 3 months the battery is saying "Service Battery"

This doesn't tell the full picture though, as if it use my Mac once i get the "low battery 9 minutes remaining" warning, it will go on for hours without cutting out.

Ive been told i need to do an SMC reset to address the issue, but each time i do it following Apples guides for laptops with a removable battery, it dosnt fix anything?

How can I know that an SMC reset has taken place, can it be seen in the logs ? Or can i do an SMC reset through some kind of GUI tool which will give me feedback instead of the standard way which i cant be sure has worked.

Here is an output from About this mac > System Info > Power

Model Information:
  Serial Number:    REDACTED
  Manufacturer: SMP
  Device Name:  REDACTED
  Pack Lot Code:    0
  PCB Lot Code: 0
  Firmware Version: 2
  Hardware Revision:    00aa
  Cell Revision:    2
  Charge Information:
  Charge Remaining (mAh):   220
  Fully Charged:    No
  Charging: No
  Full Charge Capacity (mAh):   3918
  Health Information:
  Cycle Count:  81
  Condition:    Service Battery
  Battery Installed:    Yes
  Amperage (mA):    -1943
  Voltage (mV): 10877

System Power Settings:

  AC Power:
  System Sleep Timer (Minutes): 3
  Disk Sleep Timer (Minutes):   0
  Display Sleep Timer (Minutes):    3
  Wake on AC Change:    No
  Wake on Clamshell Open:   Yes
  Wake on LAN:  Yes
  AutoPowerOff Delay:   14400
  AutoPowerOff Enabled: 1
  Display Sleep Uses Dim:   Yes
  GPUSwitch:    2
  Hibernate Mode:   3
  PrioritizeNetworkReachabilityOverSleep:   0
  Standby Delay:    4200
  Standby Enabled:  0
  Battery Power:
  System Sleep Timer (Minutes): 10
  Disk Sleep Timer (Minutes):   0
  Display Sleep Timer (Minutes):    2
  Wake on AC Change:    No
  Wake on Clamshell Open:   Yes
  AutoPowerOff Delay:   14400
  AutoPowerOff Enabled: 1
  Current Power Source: Yes
  Display Sleep Uses Dim:   Yes
  GPUSwitch:    2
  Hibernate Mode:   3
  Reduce Brightness:    Yes
  Standby Delay:    4200
  Standby Enabled:  0

Here is an output from the command system_profiler SPPowerDataType | grep -i "charge information" -A 10

Charge Information:
          Charge Remaining (mAh): 234
          Fully Charged: No
          Charging: No
          Full Charge Capacity (mAh): 3918
      Health Information:
          Cycle Count: 81
          Condition: Service Battery
      Battery Installed: Yes
      Amperage (mA): -2579
      Voltage (mV): 10890
  • Please post the output of the command system_profiler SPPowerDataType | grep -i "charge information" -A 10 to your question. An SMC is just Apple's name for the PMU (power management unit) that every other laptop uses. A reset will simply removed the saved values it measured up to that point; starts it off fresh. There's no log and you cannot access it via a GUI – Allan Nov 10 '18 at 19:44
  • @Allan for instance i have been using my laptop for about 40 minutes right now since i had the low battery warning, saying i only had 9 minutes remaining – sam Nov 10 '18 at 19:56
  • Thank you for posting more information. See my updated post. – Ruskes Nov 10 '18 at 22:46
  • Is it a genuine battery? – John Keates Nov 11 '18 at 3:38
  • @JohnKeates its not a genuine battery, the original battery was old as it had been installed since i purchased the laptop in 2012. I was hesitant to get a 3rd party battery for obvious issues, but the apple store wanted to have my laptop in for 2 days (for a part i can swap out myself in 30 mins). The supplier was iFixit, who are reputable, so although its not an Apple original part, its not a eBay piece of rubbish. iFixit have agreed to send me out a replacement battery. – sam Nov 11 '18 at 12:49
2

It's quite possible you have a defective battery, bad cable or power handling chip issue on the logic board itself. From the output you posted, here's what we know.

  • 81 cycles and FCC of 3918 mAh is way out of specification
  • The Voltage and charge measurement that you have 234 mAh (mili-amp hours) remaining
  • It's showing a draw of approximately 2.5A (battery is being drained)

The SMC can only accumulate how much battery capacity is left by measuring the current power against the current draw and known full capacity. In this case, it's measuring that you're out of power and indicating your battery needs to be serviced.

There's no "dipstick" that can give you the actual charge, the SMC must calculate it and from the data it's getting from the battery, it thinks it's failing even though it continues to work.

Your best bet is to replace the battery (it's probably still under warranty) and still more likely to be the cause if you were careful with the cables and reseated them.

  • Thanks @Allan , ill give that a try and let you know how i get on – sam Nov 10 '18 at 20:14
  • 1
    Keep in mind that the bzq-series of gas gauge IC's used in pretty much all MacBooks do use the smart battery specification containing both design capacity, current capacity and status. This is matched against a number of power sensors on the MLB side which are read by the SMC. The SMC doesn't simply track and calculate (like the PMU did) but takes (correct) data from the smart battery in to account as well. – John Keates Nov 11 '18 at 13:10
  • @JohnKeates our friend Allan needs bit more help from you explaining how it works. I am unable to accomplish that. He is stuck on believing the SMC actually measures battery parameters and there is no other circuit doing that, as you pointed out to him. – Ruskes Nov 14 '18 at 22:26
-1

Reviewing your Battery report:

Considering you installed it as "new" 3 months ago, unfortunately it behaves as 3- 5 Years old.

The Full Charge Capacity (mAh) value is down to 3918 (<50%) !! which is the absolute indicator of battery life, not so the cycle count.

(new battery comes with ~8200 mAh that gradually over 5 Years goes down), once it reaches below 50% you will get the Service Battery.

Replace it.

You current consumption Amperage (mA): -2579 has nothing to do with anything, it is a variable that changes depending on the load.

If you plug in the Charger that number will go positive. (= Charging)

Also the remaining charge has nothing to do with battery life.


SMC can not read the battery values directly. There is a chip (IC) integrated with Battery called a SMBus chip or Gas Gauge or even Dipstick. It reads the analog values from the batter, coverts to digital and sends that to the SMC.

That is how it is possible for SMC to know the cycle count (and other values) even when you move the battery from one Mac to another.

enter image description here

An SMBus battery contains permanent and temporary data. The battery manufacturer program the permanent data into the battery, which includes battery ID, battery type, manufacturer’s name, serial number and date of manufacture. The temporary data is added during use and contains cycle count, usage pattern and maintenance requirements.

To your second question ...How to see if SMC reset worked.

While doing it, watch the MagSafe plug light, it will briefly flickers if the reset was successful.

  • question updated with about this mac power info – sam Nov 10 '18 at 20:01
  • i redacted the serial number and device name – sam Nov 11 '18 at 12:50
  • @sam thank you, see my updated post with more information. – Ruskes Nov 11 '18 at 16:51
  • thanks, could you expand upon the MagSafe colour change, i wasnt aware i had to have the laptop plugged into the MagSafe whist running the SMC reset, also what colour dose it change to / from ? – sam Nov 12 '18 at 10:54
  • You should read the article. The voltage is typically measured in 1mV increments; the current resolution is 0.5mA; temperature accuracy is about ±3ºC. The SMBus measures the state-of-charge at that time and does a calculation, it cannot act as a "dipstick" and tell you "there's this much charge remaining. – Allan Nov 14 '18 at 15:42

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