Just installed Elementary OS on my Macbook pro (2010) with the battery on full charge. I boot up elementary and suddenly I'm told it's on 7%. Granted, my battery is horrendously weak (1hr to reach 0% on macOS), but the charger is always connected and indicating that the battery is at 100%. When I remove the charger though it legitimately seems like the battery is 7% since it decreases every 3 mins (as seen on MacOS), and once it reached zero it requested that I remove the installation device and press enter (consequently shutting off the mac). Without plugging in the charger I boot the device (this time to macOS) and it tells me the battery is at 33%??? Multiple google searches got me nowhere. Anyone has any idea what's wrong?
There isn't anything "wrong", per se. This is just a matter of elementary OS using different math from Apple. Let's look at how these two OSes can show different numbers for the same hardware.
Note: As I'm not sure whether you're using a 13" or 15" MacBook Pro, I'll use the battery specifications for the 15" model from 2010.
First, let's take a look at what sort of statistics your battery has to offer with
upower -i `upower -e | grep 'BAT'`
This will give you something like the following:
native-path: BAT0 vendor: SMP model: 45N1149 serial: 3126 power supply: yes updated: Thu Aug 5 04:14:40 2021 (106 seconds ago) has history: yes has statistics: yes battery present: yes rechargeable: yes state: fully-charged warning-level: none energy: 43.93 Wh energy-empty: 0 Wh energy-full: 43.96 Wh energy-full-design: 56.16 Wh energy-rate: 38.691 W voltage: 12.197 V percentage: 99% capacity: 78.2764% technology: lithium-ion icon-name: 'battery-full-charged-symbolic'
Note: This battery output is from a Lenovo Thinkpad W541. Yours may look different.
When macOS is determining your battery life, it looks at the
energy-full values to determine how much life remains, while elementary OS (and many other Linux derivatives) look at
energy-full-design. With this in mind, let's do some math.
A 2010-era 15" MacBook Pro notebook usually ships from the factory with a 63.5Wh battery. 7% of that would be about 4.45Wh.
||4.45 / 4.45||100%|
||4.45 / 63.5||7%|
For many Debian-based Linux distributions, the "critical battery shutdown" takes place at 2%. That works out to about 1.27Wh.
||1.27 / 4.45||28.539%|
||1.27 / 63.5||2%|
If we take into account the energy rebound that takes place after a battery stops discharging momentarily (as well as Apple's propensity to use round, "people friendly" numbers whenever possible), we can consider the 33% value that macOS reports as a rounding error.