I replaced my 6S battery last January and, since this summer (6 months later) the performance has been dropped dramatically. After a full charge, this morning it have lost 25% of charge in 20 minutes and many times when it has less than 20% the iPhone shuts down. With less than a year, the new battery has worst performance than the original with two years. The iOS battery health indicator is at 92%.
I called Apple service and they told me that the battery is out of guarantee, because the replacements only have 6 months.
My impression is that the replacement batteries they’re using have a very poor quality and they loose performance very soon.
This is interesting. I have a 6s and had the battery replaced for free under the warranty program from a few years ago. It was replaced in July 2017. Oddly, after only 370 cycles, the battery health via the battery app was at 80% and I got an unexpected shutdown.
I took it in last week for the $29 replacement and even the tech thought it was strange it had depleted that quickly. Their diagnostic showed everything else to be functioning fine. The replacement only took about 45 minutes which was nice. I’m curious to see how this one holds up.