iphone 11 battery drainage

Old wives' tale. It is impossible to overcharge the battery. The "charger" is in the phone. Please read what battery expert Lawrence Finch and Apple has to say:

There is never a time when any smartphone is doing nothing, so it will use energy 24/7, and the amount used will vary from day to day and minute to minute. For that reason alone you should charge your phone overnight, every night. In addition, the absolute best way to get maximum use on a charge, as well as slow the decline of battery capacity long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight.

The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. 

If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates. Here's more information→About Optimized Battery Charging on your iPhone - Apple Support

My iPhone 11 Pro is 3 years....36 months.....old. Battery Health is 94% using the advice above since the phone was new.

Why are you not connecting to the phone to the charger and leaving it connected all night.....every night? The is the single best that you can do to preserve the life of your battery if you have Optimized Battery Charging enabled on your phone.

Try leaving the phone connected all night for a few weeks.

If no improvement, you can take the phone in to an Apple Store or Apple Service shop and have them check out the battery. Apple will not normally install a new battery unless the Battery Health is down to 80%

Your next battery will perform better and last longer if you apply the advice in the battery info above.

Err0r626 wrote:

ok thankyou so much. but what do I do when my battery doesn't want to hold a charge for very long? can I simply take it to a store and get it replaced?

83% is pretty close to when Apple considered the battery no longer fit for use. Apple's diagnostics, which are far more accurate than the Battery Health indicator on the phone, may show that it needs to be replaced. I would definitely consider contacting them.

Apple recommends replacing the battery when it reaches 80%, yours is very close to that.

Look here -

iPhone Battery Repair & Replacement - Apple Support

See here:

When to charge your iPhone or iPad - Apple Community

Check the battery health in Settings>Battery.

Err0r626 wrote:

because it was always said that leaving it plugged in overnight is bad for your battery

That’s false.