is charging phones, laptops 80/85% really makes battery last long?

Charging your phone or laptop to around 80-85% can help extend the lifespan of the battery. Lithium-ion batteries, have a limited number of charge cycles, tend to degrade faster if they are consistently charged to 100% or drained to 0%. Maintaining a charge level between 20% and 80-85% is generally considered a good practice to maximize battery life. Additionally, avoiding extreme temperatures and not overcharging can also help prolong the battery's lifespan.

Yes as far as my experience with smartphones suggests. The original batteries in two Redmi devices soon starting their 7th year are still in pretty good condition. 

now its

10% - 90%

keeping your battery in this range will increase its life span

avoid keeping your phone under direct sunlight / overheating

also wireless charging / slow charging is better overall

use wifi calling over airplane mode whenever avalable

Yes still using a nearly 5yr old ph without changing battery so it works definitely but cureent rapid fast charging will make sure ur battery die in 3yr or so, that's why in some ph there is option to disable fast charge

Battery temp is more important that charge levels. Everything else is just here-say, when you don't go to extemes, battery stats on lower end of temps

There is no harm in following this rule.

Just don't follow it so hard and preach it to anyone who comes your way.

It's ok to charge till 95 when you are going for a trip or similar.

Be happy..!

I have set my Lenovo laptop in conservative mode where battery charges only upto 55-60% and rest of the times it works directly on ac power, it helped me keeping my battery capacity more than 90% even after 2.5 years. Whenever i have to work outdoor, i charge it fully and it gives good battery backup 

Modern Technology   is  weird . Why  have  that 0%  - 100 % blunder than .   Just  business  profits  noone  cares  for quality  now . After  rippjng  off so much money  on buying mobile phone  , you don't  get a charger ,or anything else than the phone itself even that has battery   Nautanki , and that to fixed

You and I are not physics and/or chemistry experts. So, we go to people who employ them. If Tesla recommends not charging their car batteries beyond 80% unless you have a long trip planned, then I believe there must be a good reason for it. Apple used to give a setting to limit battery charging to 90% (seems to have been removed with the iOS 17 or 17.1 update) and Samsung still has one to limit it to 85%.

https://www.reddit.com/r/teslamotors/comments/1...

If it was, it would have been mentioned in the user manual. It makes no sense.