The two settings are not the same
Optimised Battery Charging holds the phone at 80% and finishes charging just before you normally wake, learning your routine. You still get a full battery each morning; it just spends fewer hours sitting at 100%.
Charging Limit, on models that offer it, caps the battery at 80% permanently. You never reach 100% and you accept shorter days in exchange for slower ageing. Settings → Battery → Charging holds both.
Why sitting at 100% is the problem
Lithium-ion batteries age fastest when held at a high state of charge, particularly when warm. A phone that spends eight hours a night at 100% on a charger accumulates that stress every night for years.
That is what both features address, from different directions. Neither is about how often you charge — the cycle count barely changes.
Which one to use
For most people, Optimised Battery Charging is the right answer and it is on by default. It removes most of the ageing stress without costing you any usable battery, because the phone still reaches 100% by the time you pick it up.
The 80% limit makes sense in narrower cases: a phone that lives on a car mount or a desk dock all day, or one you are deliberately preserving because you intend to keep it for many years. If you regularly need a full day away from power, it will hurt.
What it does to daily endurance
You lose roughly a fifth of your usable battery, and it is exactly as noticeable as that sounds. On a phone with a healthy battery and light use it is unremarkable. On a phone already below 85% capacity it can be the difference between reaching the evening and not.
You can toggle it off temporarily before a long day and back on afterwards, which is what most people who use it actually do.
Does it meaningfully extend battery lifespan
Directionally yes, but the effect is measured over years rather than months, and heat matters at least as much. Charging in a hot car, gaming while charging, or leaving the phone in direct sun does more damage than reaching 100% ever will.
The honest summary: leave Optimised Battery Charging on, avoid heat, and do not worry much beyond that. Our battery health guide covers monitoring the result.
If your battery is already worn
None of this restores a battery that has already degraded. Below 80% Maximum Capacity, a replacement is the only thing that changes the outcome, and it is inexpensive relative to a new phone.
Our replacement guide covers the signs and the cost.
Frequently Asked Questions
What does the 80% charge limit do?
It caps charging at 80% permanently, slowing battery ageing at the cost of about a fifth of your daily endurance.
Is the 80% limit better than Optimised Battery Charging?
For most people no. Optimised Charging removes most of the ageing stress without costing usable battery, because the phone still reaches 100% by morning.
Does charging to 100% damage an iPhone battery?
Sitting at 100% for long periods, especially while warm, ages it faster. Reaching 100% briefly is not a problem.
Does the 80% limit make the battery last longer?
Directionally yes, over years. Heat matters at least as much — avoid charging in hot places.