I held on to my 8 Plus for little over two years and it remained excellent most of the time -- although I had to replace the battery before reselling it because it was at 83% capacity.

I also always charge my phone overnight even if it's at 70% (which it routinely is) because I've been bitten by going out and about with 60% charge and having to spend 12h outside and my phone died. So I just started conservatively charging it each night no matter what I expected for the next day.

But yes, for most people an iPhone can easily last two full days and still be at 15-20% when you finally plug it in on the second day's end.

iPhone batteries are only rated for 500 cycles of 100% -> 0%. Or, to look at it differently: You can charge 1 percent of your battery 50,000 times on your iphone before Apple no longer guarantees under warrantee that your battery will hold 80% of its original capacity.

Caveat: every percent is not equivalent. Charging above 90% is harder on your battery than charging from 40-50%. Charging and even just using your battery while it is very hot (90 degrees or above) or very cold (below freezing) is also very hard on it. Apple defines operating temperatures as:

> Use iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F)

and claims that using the phone outside those temperature ranges can permanently shorten battery life. Bit silly when you live someplace like I do where 60% or more of days are outside of that operating range, but I guess Apple is really just designing for Cupertino temperatures.

Basically after just 365 days of phone ownership, you're probably already over 50% of your way through your battery and capacity might be reduced by over 10%, up to 19% is still OK under warrantee. I've had a 2016 iPhone SE for over 5 years now, and I've replaced the battery twice in that time. Seems to be essentially required once every two years.

Yes, I agree with that. The two iPhones I had before the 12 Pro Max -- 6s Plus and 8 Plus -- seem to have needed a battery replacement at about the 20th month mark because the capacity was at ~85% at that point. And you being to notice. So yes, doing a battery replacement anywhere inbetween the 1.5 and 2.0 years mark for iPhones is quite expected IMO.

I've used my (original) SE for over 5 years, running it down to the 20% region (often way lower) and back up overnight at least 2000 times. Battery still seems reasonable - health on 79%.

May I ask where in the world you live? I wonder if part of the cause of your incredible battery longevity is a climate that stays safely within Apple's design specs of low humidity, moderate temperature. I've lived in areas that get very hot, very cold, and very humid regularly in the time I've owned my SE, which could contribute to battery degradation.

And above it all, batteries are very much a lottery. Sometimes you get a really great one, sometimes your battery falls apart within a year. I guess you got lucky.

Before I had an 11 I had an SE, and by year 2 or 3 the battery was so weak that I had to carry around an external charging pack for it. This got really awkward (and a little scary) for traveling and was part of the reason I upgraded to a newer model.

Right before I sold that SE to my friend I checked the battery health, and it was in the high 80s. Yet I could not get a full day's use on a single charge. This led me to conclude that that Battery Health measurement was bullshit.

I haven't looked at it before.

Apparently if I enable analytics I will get a report saying how many cycles my batter has lasted. Unless I use my phone for several hours of playing spotify and youtube I don't notice the battery dying during the day.