Eagle_Owl Batteries wear out the least if they have a 30% gap between the lower and upper range, i.e. never have less than 30% remaining charge and never have more than 70% charge.
de0u Is it possible to provide one or more sources supporting this claim?
Eagle_Owl One of the many sources you can find about this on the Internet comes from Isidor Buchmann, the founder of Cadex, a company that has been researching and producing batteries and chargers in this field for decades:
https://batteryuniversity.com/article/bu-802c-how-low-can-a-battery-be-discharged
But I don't think that page says "never have more than 70% charge". It says "30% to 80%" for automobiles, and mentions satellites without giving numbers (the link goes to a page about satellites and rovers that says "[depth of discharge] of 40 to 60 percent", which is not a narrow range).
There are other issues with that site. It's ad-heavy, for one thing. Also I'm not seeing a lot of coverage of charge rate, discharge rate, charging temperature, or discharge temperature, all of which affect longevity in addition to the charge limit and discharge limit. I can see how mobile-phone users, who can easily "see" the charge limit and depth of discharge, might focus on those two numbers, but focusing on what's easy to measure while overlooking charge/discharge rate and temperature might lead to poor results.
Is there something on that site along the lines of "We took 200 Pixel 7a's and split them randomly into two groups, then we did charge/discharge cycles with one group cycling between 20% and 80% while the other group cycled between 30% and 70%, and after four months the 30%-to-70% group had batteries that were 30% healthier on average"? Results like that might justify a request to the GrapheneOS developers to support multiple thresholds. But I'm not seeing evidence like that on that page.
Is there something like that elsewhere on that site? Or on some other site? Again, the claim was "never less than 30% and never more than 70%".