Just one anecdote, but I got my battery replaced and initially my phone was super-fast. After a few months though, it slowed down considerably, and is now as slow as it was before I replaced the battery.
The battery-protection performance throttling is either on or of, and you can check the status in iOS 12 (settings>battery>battery health). If it's off ("Peak performance mode") and your phone is slow, it's something else (bloated apps or web pages perhaps)
Not true - lithium cells see most 'wear' when used and stored above 90 percent charge and below 10 percent charge.
The effect is so dramatic that some manufacturers rescale the indicator so it isn't possible to reach those charge levels, and makers of electric cars won't charge above 90 percent by default.
Right but we're talking about the whole battery, not individual cells. I thought "prevent the cells from charging too high or dropping too low" was standard practice these days for everybody, and so at the battery level the "don't charge to 100%" advice is obsolete.
I don’t think you got that quite right. Most cellphone batteries are single cell (L shaped ones excluded). All cells have the property of degradation per cycle depending on range of charge/discharge (0-100 worse than 10-90 worse than 20-80). Standard cell phone BMS charges 0-100 because most manufacturers optimize for battery life per unit weight, not cycle count. Planned obsolescence and all that..
At the very least, the "battery" includes the circuitry protecting and mediating access to the cell(s), and that's the point where it would prevent the cell(s) from overcharging.
This site seems like a decently credible source on battery life, and they recommend setting devices into a mode to leave the charge at around 80% if its not going to be really used heavily as a mobile device.
"A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent."
I've had a lot of laptops with this kind of mode on them from several different manufacturers. I think Samsung, Lenovo, and HP have some knowledge of extending the life of their batteries.
https://support-us.samsung.com/cyber/popup/iframe/pop_troubl...
"...it is strongly recommended to select "Optimize for Battery Lifesapn mode" or Conservation Mode and keep AC adapter connected alll the time. This mode will enable the battery to be fully charged to 80% or 60% of its design capacity."
https://support.lenovo.com/us/en/solutions/ht069687
I have little reason to think a similar concept applies to phone batteries, as they're usually a similar chemistry these days.
Common knowledge and from what I've read about batteries the last two decades. And from using AccuBattery.
Please do state why it is wrong, so we can sort it out :)
Both samsung and apple says that you should have at least 50% charge if you store the device long term and also avoid going too low and leave it empty.
I get that apple/samsung will not recommend not charging 100%, from using accubattery (play store) they say that a full charge uses about one charge cycle, but charging to 82% does not take any charge cycle.
From what I've read the best thing for the longevity of the battery would then be to have it between 20 and 80%. But if you will replace the battery or phone after 500 charging cycles you could just charge it to 100% as much as you like. But never go below 20%.
AccuBattery should really add a warning about the battery health when going under 20%.
I did not know that it's possible to monitor battery health in iphone settings nowadays, that's great!
Can you share why it's wrong? I learned the same thing as the OP and would love to learn more. As far as I learned, the more harmful part is discharging to very low levels, especially if you use it until it shuts off and then don't connect it to the charger for a long time. Is that also no longer the case?
I know that manufacturers sometimes gate off some of the capacity so that the battery doesn't actually reach extremely high or low levels of charge, but that would still imply that avoiding the very high and low ends of the reachable spectrum would still be helpful, just maybe not as much.