Summer and winter is a consideration. Saw numbers but can’t remember so won’t say I know right off.
Tesla says to expect the battery to degrade at least 3% per year no matter how it is treated.
If that is for reals it confirms what I always figured that years hurt them more than miles, kinda like the lithium ion batteries in my dewalt power tools... new they are usable and work all day fast forward 5 or 6 years it will barely do one set of lug nuts before I got to swap batteries to another one that barely will do a set of lug nuts then swap back to the first one thats been charging. The batteries are not technically dead as I can still make do with them (for now) but when it is time to replace the batteries it is cheaper to buy new tools. My 92 dakota with the original drivetrain still goes basically the same exact miles on a tank of fuel as it did new where a new battery powered car would have needed at least 3 $15,000 batteries in that span even if it was only driven the same 140,000 miles.
Today’s lithium power tool (and cell phone) batteries degrade mostly only when
they are above roughly 68% of full charge.
EV makers like Tesla understand this present day lithium battery chemistry problem and limit their “full charge voltage” to about 80% to make the battery pack have a useful life that the customer will accept.
I buy Milwaukee and Ryobi power tools because they have Samsung Li batteries inside their battery packs.
If I am actively using them I will charge them up to 100% but I always run them down below the 75% level when I know the battery is going to sit overnight or longer.
I have bought a couple cheap “Chinese Knock off” Milwaukee and Ryobi battery packs that are about 40% of the Milwaukee/Ryobi prices but during testing have found that they are about 75% of their rated amp-hrs, so that if they degrade 125% faster their “bargain price” will not save any money.
I bought a 2016 Google Pixel XL cell phone.
For about a year I just plugged it in when it was below 50% and charged it to 100%.
Then on Reddit’s Google Pixel subgroup I read other user’s warnings to limit charging to 70% or less and use the app AccuBattery Pro to sound an alarm when your battery is at any % charge level you desire. AccuBattery told me my 3450 milliamp-hour had declined to 3000 at that time, but by limiting charging to 68% after six years my battery degradation slowed down a lot and has more or less stayed at 2660 milliamp hours, which gives me up to two days of use.
With EVs, power tools, or cell phones
you can extend Li battery useful life a lot
if you avoid letting the battery spend much time sitting between 68% to 100%
You can still charge to 100% if you know you are going to draw it down quickly.
Of course, Apple, Google, DeWalt, Milwaukee, Ryobi,
love the profits of selling their customers either new devices or new battery packs,
which are priced like computer printer ink cartridges.
