iPhone 6s battery issue

[PJMcK]

3. It could be your charger

The little wall wart that came with your phone is only a 5-watt charger. If it's damaged or under-performing, your phone won't be getting a full charge. From your post, it sounds like your phone isn't really powered up unless it's plugged in.

If your Settings indicates that your battery still has an 88% capacity, I'd consider buying a new, higher wattage charger, like 15- or even 30-watts. Your phone will charge much faster. Anker makes some really good products and their cables have a lifetime warranty. They're less expensive than buying a new phone!

Actually, I have a 6S and I'm going to buy the new 12 mini. It's a bit pricey but these phones can last 5 or 6 years. If you amortize its cost on a daily basis, they're not too much money.

Good luck and Happy Thanksgiving!