My iPhone 15 Pro Max battery health decreased by 2% in the last days

There are multiple threads about this. First, the battery health percentage is not in real time and may appear to not change for months and then you may notice what appears to be a fast drop. Unless your iPhone 15 Pro Max is fairly new being at 92% isn’t declining really fast (you need to provide a little more info such as how long you have owned it assuming you are the original owner). Regardless, as it currently stands there is nothing wrong with your battery health and there isn’t a problem to address (anything above 80% is going to be normal).

Batteries - Maximizing Performance - Apple

Ways to help with your battery performance and lifespan in the link above.

Battery Health is not a linear slope. It can remain steady for a while then take a sudden drop of a percentage or more, and in some cases can even increase. It's all in how the algorhythm tries to make its best estimate of the remaining capacity. How many charge cycles does your iPhone show that it's undergone?

How long have you had the phone? On average over several months it is expected to drop about 1% per month. The drop is not linear meaning that some months will not drop at all and other months will drop more. Any single month is not an indicator of what to expect in future moths. Given that you are at 92%, you would be above average if you purchased the phone new more than 8 months ago.

The phone will only calibrate when it has the chance to charge to 100%. Some users who attempt to control the charging by not charging anytime after 80% or 90% find that once it does charge to 100% to calibrate, they notice the dramatic drop as it had not been given that opportunity before.

.......2 days ago last Tuesday it was 94% and today it is 92%......

On a quick glance, that does look like a 2% drop, but you might not be aware of how Apple displays the Battery Health settings.

Apple always rounds any tenths of a percent down to a whole number. So, 92% might have really have been 92.9%, but that number is rounded down and displayed as 92%.

The actual drop might have been from 94.0% to 92.9%.....a drop of only 1.1%.

But......Battery Health is only important over longer periods of time. I've seen one phone display 98% for five months, then suddenly drop to 93% the next month.

All that you really need to remember is that the battery should be replaced when it is down to 80%. Everything else is pretty much meaningless.

284 cycles and I had the phone since November 2023

Since Battery Health normally declines 1% for every 25 Charge Cycles, the battery should have declined by 11.4%. ( 284 divided by 25 = 11.4%)

So, 100% minus 11% = 89%. That is where I would expect your battery to be at this time.

You report that the battery is at 92%. Your battery is doing better than average. I wish that my battery was doing as well as yours, but mine is simply average.

Stop worrying about your battery. There is no need to be checking the battery all the time. Replace the battery when it is down to 80% in the first quarter of 2026.

Runii95 wrote:

I had the phone since November 2023

That is better than average. I would expect 89%-90%. You have nothing to worry about.