iPhone 12 Pro Max — poor battery life

Found why mine was draining so quickly, Amazon music app ! No idea why is as I’ve had the app for a long long time, but found it was using 75% of battery ! If you go to battery in settings, you can see what is using most of the battery. I updated aAmazon music app and been fine since

The best way to find out is to go to your battery health and see what is consuming your battery, you have tabs for “last 10 days” and “last 24 hours” there it will tell you what app or what activity of yours consumed the battery in %. It will also show which apps “background” is consuming battery. You might want to then disable backgrounds of app’s you don’t want them to be active. However’ after doing all this you might still consume more battery because of screen time. Tweak the best option for you. However, I still feel the 12 Pro Max battery is not that great or probably the latest update wrecked it. I have attached a photo sample view

if you keep it for an overnight charge your battery health will go poorer earlier than was expected of it and if you are not havin apple care you will end up replacing the battery at a considerable cost sooner. The battery performs best at less over charges & less over heat. Overnight charges are bad for all batteries does not matter iphone or other brands. You might want to see these threads to tweak it to last longer:

About Optimized Battery Charging on your iPhone - Apple Support

Batteries - Maximizing Performance - Apple

I had the same problem with the excact same storage space, but i do have some tips for you: turn On auto brightness or just don’t have it on max all the time no matter how much you want to, I keep it at about 40-60% brightness and that gives me about 20-40% more if you don’t use Bluetooth that often i reccomend turning off Bluetooth Even though it doesn’t extend battery life that much and you could also turn On battery staving mode or glose your apps after you use them if you’re not roing to use them right after. Hope this helps!

Most people connect their phone to a charger overnight.

What did your Battery preference pane show used the power?

An easy way to duplicate this is to

leave a GPS app or anything else that continuously interrogates Location Services running.

No "tweaking" required.

Plug it in or put it on a charger while you sleep.

You can't compare iPhones that way.

In particular, if you have 5G service, you will see higher battery usage.

Samsung actually explains this nicely:

You may notice that your phone's battery drains faster than usual while you are connected to a 5G network. This is a limitation of the current 5G networks, and will be improved as the networks expand.

At this time, the 5G networks are only used for data connections and are not yet capable of carrying phone calls and messages. Your phone will need to maintain a connection to the 3G or LTE network in addition to the 5G network so that phone calls, text messages, and data will be delivered consistently.

Because your phone is connected to multiple networks simultaneously, the battery will drain faster than one would typically expect, and the phone may get warmer than when solely on 3G or LTE. …

As the 5G networks grow in capacity and capability, they will be able to handle more of your phone's functions with less battery drain.

https://www.samsung.com/us/support/troubleshooting/TSG01201462/

You’re probably using an unoriginal charger which charges at a very low rate, you could also be using an old charger or a charger that doesn’t support fast charging

Even if you tweak all that including, it will still drain quiet fast. I think the battery is poor in this design, and is unable to cope up with increased memory (I have 256GB) and watch synch. I had 11Pro Max and it was doing OK with the same app's and watch synch.

I bought that and is the same, I changed the 5G to LTE and the battery last a little bit more. Also, my phone don’t get too hot. But is really weird we have to make so many changes in order to save battery in a phone less than a month old 😣

How can you "not use" your phone if it's fully charged?

If your battery is being used within "hours" what does the Battery pane say is using the energy?

Does the issue continue in low power mode?

There's nothing to "make right" here, though Apple Support can help you further:

Contact - Official Apple Support

Do what a billion other users do:

Charge the device while you sleep.

I agree, I charge overnight but phone battery discharges so quickly once charged, 50% gone in 3 hours with little use and no gaming, never had an iPhone with such poor battery life !

Why don't you just leave it plugged in overnight like most?

The only time mine is not on a charger is when I am out and about; it's connected at home and any time I'm in my vehicle.

iPhone Battery and Performance - Apple Support