[iMore Question]

My fully charged iPhone 6 drains quickly and then arbitrarily shuts itself down saying it is low on charge when there is 30 - 40 - even 60+% power remaining. When I plug it in it returns to the previous power level.

[mark-d]

Check your iOS is up to date

If that fails set up your phone again from a fresh start rather than using a backup

Alternatively you could contact Apple support and ask them to run diagnostics. If it is a faulty battery they'll replace it for you at a cost if you're out of warranty.

Be aware that one of the iOS beta updates did something similar to my phone although it was 32% was the number for me! It's ok now there's been another updated beta issued so it may be your iOS version

[Larry Cook1]

When my six did that it was a bad battery.

[SprSynJn]

Had my iPhone 5 replaced because it would shut down at 20%.

[mark-d]

My iPhone 5s has a faulty battery but it still didn't shut down till 0%. It drained very rapidly and taken off charge at 6am wouldn't even make it till lunchtime with a normal usage.

My 6s did the early shut down at 32% a few times but thankfully that's gone now that the latest iOS update has dropped.

I understand it can be frustrating though. When mine 5s was going through battery diagnosis trying many different things I bought myself a second hand mophie juice pack which was an absolute life line