Originally Posted by
Shimmy100 Hi all. Moving from a 4s to a pre-used 6s. It has arrived. I wanted to check battery health but find it is running ios 11.2.5. I believe battery health check came with 11.3? I was wary about updating my 4s so kept it on 7, where it ran great. So whats the best ios for the 6s please? I am not a huge app user, but will be adding some going forward. Thanks all.
My 4s will no longer update beyond 9.3.5, so that's that.
Re the 6s, it is better to update the OS to the latest both for the optimization (speed) and the security reason. My daughter is still sticking to the 6s, although replace the battery), and the latest OS (even the latest 12.2 beta) and totally happy with it. But you may want to check if it is eligible for the discounted battery replacement (you are. supposed to be able to check the eligibility by entering your S/N (or IMEI?) in the Apple site. It had an issue which I do not get into here. But in any case, for the 6s, my recommendation is to replace the battery with a new one anyway. I took advantage of the US29 battery replacement program for my 8 and SE, and SE got a brand new life.