Baffling iPhone 5 battery problem

[jwkay]

I know, not another iPhone battery thread! I've read pretty much all of them in search of help, but this one is beyond me.

The phone: iPhone 5, 64GB. The battery was replaced earlier this year and, according to Coconut battery, is still at 100% of original capacity.

Up until a couple of weeks ago, I was regularly getting the following out of the phone, with 10% still to go:
Usage 8.5 hours
Standby 32.5 hours

Suddenly this has dropped massively, whereby I'm getting on average
Usage 2 hours
Standby 10 hours

The percentage of battery useage per app shows no abnormalities.
I have tried restoring the phone, and setting it up both from a backup and as a new device.
I've turned off the myriad of settings the various threads suggest, but to no avail.

The most baffling thing is there is still enormous battery drain in flight mode!
I put my phone into flight mode at about 11pm with 100% battery. At 7am its dropped to between 40 and 50% ! Useage shows nothing out of the ordinary, the phone is not warm, the battery appears simply to be discharing for some reason.

As I say, having tried everything and then some which is suggested elsewhere, I'm pretty baffled. Does anyone have any suggestions? I find the huge drain even in Flight Mode very odd indeed!

 

[dr.delinquent]

Sounds to me like a hardware malfunction. Perhaps the replacement battery was of sub-par construction standards? For something like this a multi-meter would be of great benefit. You would have to test the replacement batt. Did you replace it yourself or was it done through a third-party source?

 

[chscag]

The phone: iPhone 5, 64GB. The battery was replaced earlier this year and, according to Coconut battery, is still at 100% of original capacity.

Who replaced the battery and was it a quality battery or an inexpensive Apple knock off? If it was replaced by Apple, take it back to them and have them check it out. Definitely either the battery or charging circuit is a problem.

 

[BrettApple]

I've had third party and even OEM batteries be hit or miss. The last one I put in that has actually been doing well was something like a Stalion brand I think. Some last a year, some don't. But for $10 or so It's worth it to replace it.

 

[jwkay]

My impression is it's hardware related, too.
The replacement was done with a third party company here, as Apple don't offer replacement batteries here.
It's still got about 6 months of the guarantee to run, so it looks like I should take it in for them to test.