[iMore Question]

I have iPhone SE with a new replaced battery 1 month ago. But I can;t figure out - either when using different cable or charging with Power bank Or not charging the phone to the full 100% the phone starts lasts more less - about more than 30% less.

I found that the last time this was fixed when upgraded from 12.1.3 to 12.2 beta. But now I tried to reset with iTunes to 12.1,3 after that to beta, but the battery is alwful again. What to do?

[Annie_8plus]

There are all sorts of possibilities that could be the cause. To clarify, so that we can help you better, are you using a power bank to charge your iPhone? Also, are you using the original cable?

[xanadome]

If not a bad battery:
1. It might be the iOS version but it should not drain the battery so drastically so fast.
2. Although Li-ion batteries do not have to be discharged and recharged (cycling) periodically, I read somewhere that it is better to be cycled down to full discharge (not below 5 % preferably. Completely depleting the Li-ion battery is harmful. So they say) 2 or 3 times before you put it in service. For more than a decade (from my camera days), I do this almost as a ritual and seems to be working.
3. More likely reason is something is lurking behind the scene. Usually a reindexing of the spotlight, which might last a few days before it settles down.
4. Certain apps might be busy using the CPU constantly and hogging down the battery. The most likely cause.

[Ledsteplin]

How high you charge has nothing to do with how fast it discharges. It just seems like a 100% charged phone lasts longer. Think of it like a car. When you fill the tank up, it seems like it gets better gas mileage. It doesn't. In my experience, excessive battery drain is usually an app or apps running wild in the background. I usually swipe out the suspect apps. Then do a hard reset (reboot). This works most of the time. Turning on Background App Refresh helps the apps run more efficiently, using less resources. And remember the big 3 battery users are screen brightness, location services, and Push notifications. Anytime you can cut back on those helps.