Battery draining overnight Iphone SE 3rd generation.

Bought my 3rd Gen in March 2022. This overnight battery draining issue has been happening to my phone periodically for the last 1 1/2 years. Apple Geniuses could not diagnose it but tell me my battery strength is 100% (which I already knew from checking it). I have taken to doing screen shots to keep a record of this. Jan 23, 2023 drained from about 40% to zero. May 21 drained overnight from 48% to 18%. June 15 from 90% to 48%. June 29 from 25% to 5%. Aug 30 from 92% to 49%. Nov 10 from 73% to 18%. Battery health right now says it is at 100%. If I charge overnight the next morning it is always at 100%. I turn my phone off every night. So it is draining with the phone turned off. Nothing that I know of is running in the background. Any suggestions?

If you turn the phone off and charge it overnight, and it is not 100% in the morning, then the battery is bad. There are many failure modes for batteries; loss of capacity is only one of them.

Here’s another test. Charge it to 100% near the end of the day, then power the phone off after disconnecting it. It should be at 100% when you turn it back on. If it isn’t there is an internal drain in the battery itself.

By turning the phone off, do you mean you put it to sleep, or you actually hold both buttons until it says “Slide to Power Off” and you then slide to power off, and the screen goes black? If you do that, the battery should be exactly the same (within a couple of percent) as it was when you turned it off. If it isn’t you have a back battery that is “self discharging”.

If you just lock the screen, any cell phone uses energy continuously, as long as it isn’t powered off. This means that if it is not connected to power for 8 hours the battery level will be lower at the end of that time. How much lower depends on what apps you have, how many notifications you have enabled (which will be delivered and processed by apps even if you force close apps-they will relaunch when a notification arrives), and, probably most important, how strong your cellular signal from the network is; your phone maintains a "conversation" with the network so your phone can be found when a call or text arrives, and low signal strength requires much more energy to do this update to the network. Thus, you should be charging your phone overnight so this nighttime usage is powered by the external source rather than the battery.

Thanks for the quick response.

I hold the right side button until it says "Slide to Power Off", slide to power off and then the screen goes black . I only put it sleep when I am not using it during the day.

I normally wait to recharge the phone until the battery gets down to about 20%. It can take the battery 3-5 days to get down to 20% at my normal usage. By "back battery' do you mean the phone's main battery I am charging up?

The genius bar employee thought that it was the third party charger I was using so I bought a new one from the Apple store. It obviously didn't help. His other thought was that it was a software issue and that I could reset the phone back to it's factory settings.

Iphone SE 2020 also. dead out of the box when brand new, and drains even powered off. it was a gift for my best friend, but worked normal for a couple of years then it suddenly just "died". I bought a used SE2 and took the "dead" one back and left it on the charger for a week then it came back alive. again 🤔.

seems like the SE series are defective or has something running even when off. definitely drains battery much faster than even the old 6s which i duplicated/recovered to as backup. i don't run any apps, it's just an iMessage portal. I really like the red version but might have to just sell off!

i have 6s,6s plus, 7 plus no issue with battery drain when off.

I took the advice of Lawrence who responded above and not had an issue since - yet. It has only been 2 months but this has been happening every 1 -3 months since 2022. It seems kind of silly to me to be recharging overnight when the battery has gone from 100% to only 90% (I am a very light user) but have done so anyway so that it was at 100% every single morning after recharging. There have been some nights I've forgotten to recharge, sometimes several nights. The battery will drop about 10 - 20% a day depending on usage and get down to 40-50% - then I will recharge overnight. My spouse has an IPhone 10 and tells me he lets the battery get down to around 10% before recharging (and not necessarily overnight) and has never had this particular problem of overnight battery drainage. I think also that it an SE 3rd generation issue.

If it loses energy when powered off see→Check your iPhone battery for Self-Discharge.

Note that it will lose a small amount of energy when powered off because Bluetooth stays on to support the Find My Network crowd-sourced tracking, but that should be under 5%.

And you should not manually manage the battery charging; what you are doing will shorten the useful life of the battery because your phone will never run on line power. Your iPhone manages the battery automatically if you charge overnight, every night, with Optimized Charging enabled. This allows the phone to use external power for 8-10 hours a day rather than using the battery.

That’s a symptom of a battery failure.

OK - thanks. Will give it a try.