I always hear that it’s bad for lithium batteries to charge over 90% or over 90% so why is there no setting to stop charging after a certain threshold on my phone, kindle, pc or e-skate?
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Most devices do, in fact, have such a setting.
All devices balance total used capacity, charging speed, and battery life. With a laptop, you can usually choose which you want. Some phones allow you to, too. Probably, other stuff (like your e-skate, possibly your Kindle) just have whatever compromise their engineers decided was best.
For most customers, long time between charges is more important than long battery life, so engineers tend to go in that direction. Industrial applications often go the other way.
There is. It’s just not something shown to the user. Margins for what is 90% are changed in the settings. Your 100% charge capacity may or may not already be at that 90% total capacity, depending on manufacturer.
My Apple MacBook Pro frequently shows me a little notifier that says something like “charging has been stopped at 80% since we notice you infrequently use your battery: you may choose to charge to 100% by doing the following…“ Additionally, my iPhone 11 says something like “charging is proceeding at a slow rate since we see that you will not pick up your phone until early tomorrow morning“.
Because you don’t have good electronics? My phone has a setting to not go over 85%. I can also do this with my Linux systems. Probably windows too.
There is a setting in modern devices. Apple started doing it a few years ago, especially if you’re someone who charges their phone over night. It’ll stay at a medium charge and display a message that says “Will finish charging by X:XX AM” (generally right before your alarm goes off.)
Their laptops will also stay at ~80% if you leave it plugged in all the time.
It wasn’t a setting back in the day because they always wanted “maximum” performance and didn’t care about longevity.
It’s not bad to CHARGE over 90%. It’s bad to let a lithium cell SIT over 90% charged.
(There’s a little nuance here depending on the exact lithium chemistry. LFP does fine at 100%)
The reason is that as you put more energy into a cell, the voltage rises. This increase in energy/voltage is then available to power undesirable side reactions within the cell that permanently decreases the capacity of the cell. Over 90% those bad reactions really speed up. The longer you allow a cell to sit at a very high state of charge, the more side reactions occur. Hence why it’s fine to charge up if you plan to use the power right away, but if you are not going to use the device right away then maybe don’t fill it up. It’s one reason why electric cars allow you to schedule your departure time, so they can complete their charge just as you’re ready to leave.
The 0-100% that is shown to the user in reality is 10-90%~ actual capacity in the battery.
So when your phone goes 0% battery, physically there is still juice left in the battery.
this is done by ‘battery management’ using fairly complex procedures in software/bios/firmware.
user intervention generally would not help the situation.
Your phone doesn’t? Mine has an option to stop at 85%
My new phone has a setting to keep max charge at 85%. First time I’m trying it and… I feel like I’m running out of battery every day. But I guess the battery life will be more consistent.
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