Google Pixel 4a's Ruinous 'Battery Performance' Update Is a Bewildering Mess

An anonymous reader quotes a report from Ars Technica: What exactly is wrong with the batteries in some of Google's Pixel 4a phones still out there? Google has not really said. Now that many Pixel 4a owners are experiencing drastically reduced battery life after an uncommon update for an end-of-life phone, they are facing a strange array of options with no path back to the phone they had.

Google's 'Pixel 4a Battery Performance Program,' announced in early January, told owners that an automatic update would, for some 'Impacted Devices,' reduce their battery's runtime and charging performance. 'Impacted' customers could choose, within one year's time, between three 'appeasement' options: sending in the phone for a battery replacement, getting $50 or the equivalent in their location, or receiving $100 in credit in the Google Store toward a new Pixel phone. No safety or hazard issue was mentioned in the support document.

Google did not explain why only certain devices were affected, but Hector Martin -- of Asahi Linux on Apple silicon, open source Kinect drivers, and other fame -- took apart the update's binary kernel and has some guesses. Martin points out that the updated Pixel 4a kernel has these interesting characteristics:
- It seems to have been built by a Google engineer 'on their personal machine, not the proper buildsystem.' -- There is no source provided, as would normally be required of a Linux kernel build, though it may only need to be provided on request under the GNU General Public License. - The maximum charge voltage of certain battery profiles changes from 4.44 volts to 3.95, which would mean batteries cannot charge to anywhere near their former potential. - There are two main battery profiles, with distinct 'ATL' and 'LSN' markers; Martin suggests they relate to Amperex Technology Limited and Lishen, manufacturers of battery cells. - LSN-tagged batteries assigned the 'debug' profile can see capacity reduced from 3,080 milliamp hours (mAh) to 1,539 mAh. The big question is why Google pushed an automatic update to a phone from 2020. 'No news or community reports have surfaced yet of Pixel 4a devices causing fires, or even simply failing to function, after four years,' writes Ars' Kevin Purdy. 'It's an automatic update with a strong fix, but for what?'

Google's support page only states that the update will 'improve the stability of their battery's performance.'

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