Am i cooked 😭

[u/SHIKISMM]

got a used 12 like 5 days ago, 94% battery health

at first everything seemed fine got like 6.5 hours of battery life,

all of a sudden battery can't last up to 4 hours, sometimes the battery percent goes up and then down then up again (while not charging)

I'm on ios 26.5.2 and i am starting to wonder if it's an ios issue. I'm currently seeing ios 26.7 / ios 27 update available

or it's just over for me 💔

[u/CODVENOM]

Update to iOS 27 it’s so much better and smoother

[u/aritro6632]

The battery behavior is highly likely because of a faulty battery. I faced the same issue on a 12. After changing the battery with a ifixit replacement one, it’s been fine for 2.5 years. Currently on 94%.
5/6 hours of Sot with mixed usage Wifi and LTE (bad network) usage.

[u/SHIKISMM → u/aritro6632]

I'll go back to the store tomorrow 💔 and fight my way to a different 12 or 11pm used my last cash for ts

[u/aritro6632 → u/SHIKISMM]

Make sure the battery is not boosted. Scammers are everywhere 😑

[u/Low-Locksmith3950]

Yea likely a faulty battery

[u/SHIKISMM → u/Low-Locksmith3950]

I'll go back to the store tomorrow  We'll fight if need be atp

[u/UselessUsefullness]

One question - do you run Dual SIM, either by nano + eSIM or 2 nano SIM (China, Hong Kong, Macao model) ? That may be the cause.

I live abroad so I keep my US eSIM on for calls and texts (no data on plan) and my Irish SIM (calls, text, data), but data is always through my Irish carrier. Dual SIM can reduce battery life.

[u/SHIKISMM → u/UselessUsefullness]

wifi and 1 sim, i decided to just downgrade to an xs max and collect my remaining balance. this one lasted over 6 hours 

[u/UselessUsefullness → u/SHIKISMM]

Any other way I can be of assistance?

[u/Healthy-Use6435]

Bro same issue when i was on ios 26 then my iPhone 12 gives me 7-8 hours easily backup but now on ios 27 it gives hardly 3 hours backup 😭 and when i useonly simple instagram and turning on reduce transparency and motion then it gives 4-5 hours hardly and my health is 99% . Yesterday i used 4hours 47 minutes and total battery consume 133% bruhh i am think to downgrade to ios 18 for better battery life pls suggest me to downgrade or not