iPhone 6S dies within the hour after charging

Well, you can check your battery status going to Settings>Battery>Battery Health and read the maximum capacity percentage shown there. Post that percentage here.

It's recommended that only Apple Technicians (at an Apple Store or Authorized Service Provider) replace your battery (if necessary), because they only have original genuine spare parts and have tools to check / calibrate your device correctly.

Regards

Giulio

You can do it choosing your preferred / doable method (via iCloud or via computer). Follow the steps provided in this support article:--> How to back up your iPhone, iPad, and iPod touch – Apple Support

(No, you can't use your iPad to create a backup of your iPhone).

Regards

Giulio

Your iPhone's battery is reaching the critical point of its life, generally fixed at 80%.

The problem is that, in such a situation, the battery can have unpredictable behaviors.

To avoid bad surprises, I suggest that you create a full backup of your device and have its battery replaced.

Regards and best of luck

Giulio

jaltobel ~

Apple Repair

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My pleasure.

This is the list for Canada. Choose "Service & Support" or "Sales" (only Apple Stores, not resellers) and write your city's name):--> Apple - Find Locations

Regards

Giulio

Sorry, forgot to tell you: I suggest that you make an appointment (to avoid queues and to be sure the correct spare part is available).

Giulio