iPhone 6s battery draining fast even after replacement battery twice!

"Hi,

Been using cheap cables I guess?

You have damaged the tristar chip, when this is damaged, it can drain the battery extremely quickly.

You would need to take it to someone who does microsoldering, and can replace the tristar chip. :-)"

Hi, I still have the same issue even after new battery and IC replacement. Is there anything else that can have the problem?

"I buy a lot of iPhone aftermarket batteries. I estimate that 25% are “poor” when new. 75% are “very good to excellent”.

I was buying great batteries from a specific vendor, and suddenly they changed suppliers I ended up with a bunch of duds that couldn’t hold a decent charge. So beware that someone else’s experience with a vendor may not be the same as your experience.

Similarly, not all battery adhesive strips are the same. Some are good, but some of these adhesives are made so poorly that you’ll never be able to release them properly. I got a batch of bad adhesive, and battery re-replacement became a huge time sink as I spent far to much time trying to release the battery, followed by more time trying to remove the sticky remnants of the lousy aftermarket adhesive."