12 keeps turning off at certain battery percentage then back on

iPhone 12 was released in 2020, 5 years ago. What you've described is symptomatic of a failing battery, especially if the battery has never been replaced in the phone. Open Settings > Battery > Battery Health - if the battery is near, at or below 80%, it's useful life has been used and you need to pay Apple to replace the battery. DO NOT get a new battery ANYWHERE other than from Apple or an actual Apple Authorized Service Provider. No one other than they, have access to authentic Apple Batteries and non-authentic batteries will render the phone ineligible for service from Apple, and the phone will have no resale value or trade value.

Here is a link for Battery Replacement --> iPhone Battery Replacement - Apple Support

Your device has a battery issue and it needs to be replaced. The refurbisher probably didn’t use an Apple battery and it’s expired prematurely. You’ll need to have an independent repair service replace it.

https://getsupport.apple.com/repair-locations

It had a new battery when purchased as a refurb. Just dont wan to waste money on battery if not that.

Unless you buy a refurb directly from Apple, you have no guarantee that the battery is an Apple battery. Only Apple Authorized Service Providers can obtain genuine Apple batteries as a service part. Aftermarket batteries are almost all garbage.

To see if this is an Apple refurb, Do Settings > General > About. Look at "Model Number":

The first LETTER of the number holds a clue. If "F," it was properly refurbished by Apple.

If it is "N," it was a replacement Apple sent in lieu of having the owner wait for theirs to be repaired; those are also real refurbs so should have an Apple battery.

"M" indicates it was sold new. If you were told it had a new battery, M suggests a non-Apple refurb or that the battery was never replaced.

What is the battery health on the iPhone? Can you share a screenshot of the charging and usage pattern? Here is the path,

iPhone > Settings > Battery > View All Battery Usage > screenshot

Here’s mine for reference.

You've shown the battery graph, not the actual health of the battery. I'd be willing to bet real money it's not the software, but is a failing battery. Read my post above and report back with the actual Battery Health. Batteries don't last forever. It's a fact.

It’s draining abnormally fast. What is the battery health of the iPhone?

KPKPJP wrote:

Thank you for assisting me, read it would definetely be hardware . Will try new battery.

Apple won't likely touch the phone as it clearly was not refurbished with an authentic Apple battery. You could visit your closest Apple Store and see if they would be willing to replace the battery with an authentic Apple Battery. But it they won't, you'll need to visit an iFixit kind of place to have the battery replaced.

Or.......if you have an iPhone, maybe pass it down to your daughter and buy yourself a new iPhone.

KPKPJP wrote:

it wont show me , just blank . it had a new battery when purchased as a refurb. Just dont wan to waste money on battery if not that.

It was "refurbed" using unapproved parts. Apple won't touch it.

That phone is technically unsupportable.

Next time stick to Apple or authorized retailers when purchasing iPhones.

This needs to be addressed very soon because a battery in that condition can possibly damage the screen or the iPhone itself. At that point you’d need to replace the item because it would be uneconomical to repair.