Unexpected shut down, fast run down. What could the cause be?

[Roger K1]

Unexpected shut down, fast run down

The phone is a Samsung Galaxy S4 GT-I9505 with Android 5.0.1

I am getting a deteriorating performance. The phone shuts down and fails to re-boot until connected for re-charging. I also notice that when switching on WiFi, which used to be instant, it now takes several seconds for the icon to light.

The battery power runs down fast, even when the phone is switched off. 25% in a couple of hours when off for instance.

Thinking the problem was with the battery I bought a replacement from Samsung, but found no difference in the performance.

The phone, which in the past would go down when the battery reached about 20%, now cuts out at 79%, a quite unacceptable level of performance.

My speculation has moved from suspecting the battery to a power-related hardware fault, to suspecting that there are apps which drain the battery 24/7. Or that the Android version has a bug.

Power saving mode is always on, and I minimise use of Location GPS and mobile data as power saving measures. Bluetooth is always off. A fairly recent feature is an Apps Optimiser (found under Settings, Battery) that pops up with a list of apps that can be kept off when unused for 3 days etc. The options are illogical since nearly all are marked as optimising. When touched, each offers choices for dormancy, though the choices seem to repeat the already reported status 'Optimising'.

I see others on the forum with similar seriously debilitating symptoms. What's the cause, what's the cure?

 

[Rukbat]

Re: Unexpected shut down, fast run down

If the problem happens when the phone is off (which you say it does - "The battery power runs down fast, even when the phone is switched off."), it's hardware, and the phone has to go into the shop.