iPhone 15 battery percentage drops after restart

Just checking because the phone was discontinued and no longer being sold by Apple nearly 6 months ago. That would make the location where it was purchased much more relevant as it was either sitting on some shelf or had been refurbished (possibly with a third party battery) and sold to you as new.

In any case what you are experiencing is not abnormal.

• Firstly, your phone is still indexing files in the background and optimizing your photos for object detection from initial setup and that continues for about 3 - 5 days. You may also notice the device will run warmer and may experience a little bit of UI lag during this time.
• And secondly, your phone is not constantly polling the battery for updated readings as that would just increase battery use, instead it is updated every so often on a non determined schedule, but will be polled on a restart.
• Thirdly, your phone will use more battery restarting, than if you just let it sit idle and Read/Write access on the drive during startup is energy intensive. That is also why apps are just suspended in the background instead of closing, as it takes much more battery to launch an app than it does to move it to the foreground from a suspended state.

I have seen the reported range of drop on this Support Site vary between 0%-5% on restart. It seems you are right in the middle and I expect after the background processes have completed from initial setup, you will see that the drop after restart will be even less.

This isn’t rocket science. This is chemistry and what happens when an iPhone restarts. I can explain in detail but here’s an analogy.

When I start my car in the morning my battery supplies X number of amps to start my car. If my car doesn’t start, I attempt to start again. Because of the previous attempt, the chemistry of the battery has changed and can’t supply the same amount of amps to start my car.

So, how does that apply to my iPhone? I restart my device and all kinds of systems and hardware needs to restart, create communication links and much more. Starting up a processor requires a lot of battery capacity. Do you have multiple tabs open in your browser? A social media app may attempt multiple connections because of their trackers etc.

This is common access multiple generations of iPhones, multiple iOS versions etc. This is just you being over cautious. Nothing wrong with asking questions and understanding how your device actually works.

What is your Battery Health and Charge Cycles when viewed in Settings?

Did you buy a used phone?

What is the Maximum Capacity? Settings > General > Battery Health & Charging

How many Charge Cycles has the battery completed?

pranta128 wrote:

I bought an iPhone 15 two days ago, and I’ve noticed an issue. The battery percentage drops by about 3% every time I restart the phone.

In my experience, yes it does, 2 to 3%. Another reason not to routinely turn iphones off. Not sure why you would want to.

Still readily available here from reputable resellers

Yes, in US too. Just New Old Stock (NOS).

I am considering one as an AI-free upgrade to my current phone!

Makes sense to me. I have a couple of older iPhones that are definitely pre AI (7 plus, XS) that I keep ready to go.