timboxyz wrote:
Well, I initially suspected the battery dying, but I don't get "Service Recommended"
It is triggered whenever macOS detects a hardware failure with the battery or after the battery's Full Charge Capacity (FCC) drops below 80% of the original Design Capacity. The FCC is always fluctuating on the Apple batteries to some extent. Charging or even discharging the battery can modifying the FCC value to where it may be within the 80%+ range....sometimes it is all about timing.
and I do get good battery life when not plugged in with no sudden drops of capacity, it is *only* when plugged in without the PSU powered that I see the issue so far.
Disconnect the charger from the laptop instead of just turning off power to the charger. It is possible that just removing power is having some negative undesired compatibility issue.
System Information also gives good figures.
But not in real time.
You can monitor the battery information in approximately one minute increments by using the command line to retrieve the battery information including the Design Capacity so that the 80% value of the FCC can be calculated (macOS actually sees the battery capacity at about 3% higher than the command line for some reason). The following command will display the battery information while the second part of the command from the vertical bar on will save the information to a text file on the Desktop so it can be reviewed later on (will append new data to the end of the file if the file already exists....great for continuing the log after restarting the command after a full power off). The command runs until it is manually terminated by pressing Control + C in the open Terminal window displaying the output.
sudo pmset -g rawlog | tee -a ~/Desktop/battery_info_2023-01-30.txt
The command will prompt for your admin user password. Nothing will appear on the screen as you type the password, so press the "Return" key to submit the password.
The important part is the "FCC=" value. The only other value possibly of importance here is the "mA" value between the "Time=" & "Cycles=" values towards the right side of the line. The "mA" value indicates the charging or discharging current...that is how fast the battery is charging/discharging. The "mA" value will vary even if the system is under complete load especially as the battery is getting near being empty or full. Might be useful to compare when the charger is connected & disconnected when no power is applied to the laptop to compare the light switch versus complete disconnect of the charging cable. Sometimes the battery condition may be displayed when there is a hardware issue with the battery...rare, but does happen once in a while.
Variations of several hundred "mAh" or more in the "FCC=" value typically indicate a battery is starting to fail (especially when the variations go both up & down while draining the battery or charging the battery). Most of the severe variations typically occur below 20% charge or at/near full charge, but can happen at any time. Checking the Battery condition at these times, especially once the FCC= value drops below 80% of design capacity should show up as "Service Recommended" and should theoretically show up as a failure during the Apple Diagnostics....but changing the charging (connecting/disconnecting charger) can change the FCC value immediately as well. It is a complex system.
I personally find that large fluctuations in the "FCC=" value can be noticed when the battery is draining as quickly as possible during a system stress test when draining the battery (run "mprime" in Torture Test mode to use all CPU cores for most power usage) or by charging the battery as quickly as possible by letting the laptop sit idle during charging (no "mprime" and no heavy workload).
