Which method is best for iPhone battery preservation?

It depends on your preference. If you would rather start your day with a full charge at 100% for convenience or have your battery health last a bit longer over time with a charge limit. On my new iPhone 16 Pro Max, I personally choose the 80% charge limit as it is plenty more battery than I need and I always end the day with extra charge.

For both charging habits, first, you shouldn't let your battery get below 20% as it is bad for the battery health. Second, you should charge your iPhone all night, every night. Either with a charge limit or charge to 100% with Optimized Battery Charging.

Please also review the following article for maximizing battery health tips:

Batteries - Maximizing Performance - Apple

Pretty much a coin flip as far as battery performance choices.

Most users are not aware that even if you have set a Charge Limit of 80%, 85%, etc......that battery will still charge to 100% "occasionally" according the Apple's documentation.

But....to makes thing interesting, Apple does not define how often "occasionally" might be. When I've tried Charge Limits, "occasionally" was maybe 3-4 times a month. Yet, some users report that "occasionally" is closer to every 4-6 weeks, and some users report that they have not ever noticed that the battery charged to 100% even though it might have been set at a limit of 80% or 85%, etc.

The occasional charge to 100% can really upset some users....like my neighbor...who fervently believes that the battery should never be charged to anything higher than 80%, or 85%, etc. (My neighbor thinks that the battery will explode if it is charged to 100% regularly.)

He seems to forget though that he charged his prior iPhones to 100% for a number of years....before....Charge Limits appeared.

So, what is "best"? I think the answer is that there is no "best". I have yet to see convincing evidence that one setting is better than another.

Maybe what might be "best" for one user is not "best" for another.

Hello~ In addition to the previous posts…I really enjoyed this excellent user tip by *Lawrence Finch* it has some great information that you may find helpful. Click on below and review…

When to charge your iPhone or iPad - Apple Community

~Katana-San~