How do I transfer battery?

What do you mean by transfer battery? You cannot move a battery from one device to another.

You cannot open an iPhone and transfer a battery yourself. If you need a new battery in your iPhone schedule an appointment at your Apple Store Genius Bar and pay Apple $49 for a battery replacement. If you attempt to open an iPhone, Apple will NEVER touch that phone for service if you ever need it.

If you want to see your battery level % on iPhone 11 using iOS 13 or later, you can:

Swipe down (from top right corner of the screen) to open Control Center;

or

You can add a battery widget to your widgets.

If you meant something different, please better explain your needs.

Regards

Giulio

If you go to Vietnam, you can visit this store: This store will replace battery for you or you can consult your local authorized Apple store.

You can find a local authorized Apple store at: https://locate.apple.com/

[Link Edited by Moderator]

Sorry... That doesn't make any sense. You can't "transfer" a battery. Apple hasn't made anything with a removable battery is years...