[Galaxy S III Original Android Development] curiousrom:
NFC Service & Battery Life

As per my Battery Optimization post linked below & as you found out > Settings > Wireless & networks > More > toggle NFC off to save battery usage.

Settings > Apps > 3-dots show System > Nfc Service > press Memory > Memory usage > I see Average memory use 4.1 MB & Maximum usage 7.3 MB. Details Z-Ram 2.2 MB / Always running (99%) and Nfc Service 1.9 MB / Always running (99%).

Note that you can Force Stop and the Disable button is greyed out so it will run again after rebooting.

Or > Settings > Memory > Memory used by apps > App usage set to 3 hours > Nfc Service > Average memory use 4.1 MB.

If you go to > Settings > Personal > Privacy > Privacy Guard > 3 dots > Advanced > 3 dots > Show built-in apps and do not select Show user apps to make it easier to find Nfc > then swipe between Location, Personal (Nfc Service read contacts), Messaging, Media, Device (Nfc Service keep awake), Background, Bootup (Nfc Service start at boot), Root access, Other (Nfc Service read external storage & write to external storage).

Privacy Guard does not offer any choices when long press Nfc Service.

Settings > Developers Options > Running services and check both Running & Cached Processes > Nfc Service is not there so it is not running nor using any RAM.

If rooted some apps let you disable or uninstall system apps but it's not always a good thing as sometimes other services will keep searching for ever the app you disabled or it can break other system apps.

Using the app BK Package Disabler > System > long press Nfc Service > it says Is running No and RAM usage 0 MB with NFC being turned off. In the Description: "Disable NFC service can make [Settings app] crash or not work well in some devices" > if you press on Services (3) you can disable all 3 services. (attachment)

I disabled the Nfc Service & rebooted and searching for NFC in MatLog this is what I get and it's more busy than when enabled:

04-28 00:26:00.004 W/PackageManager(2383): Unknown permission android.permission.NFC_UNLOCK in package com.android.nfc
04-28 00:26:05.113 W/PackageManager(2383): Unknown permission android.permission.NFC_UNLOCK in package com.android.nfc
04-28 00:26:25.849 I/ActivityManager(2383): Start proc 3199:com.android.nfc/1027 for added application com.android.nfc
04-28 00:26:26.503 I/NfcService(3199): Starting NFC service
04-28 00:26:26.540 I/NFCJNI (3199): NFC Service: loading nxp JNI
04-28 00:26:26.903 I/NfceeAccess(3199): read 3 signature(s) for NFCEE access
04-28 00:26:27.025 D/NfcService(3199): checking on firmware download
04-28 00:26:27.025 D/NfcService(3199): NFC is off. Checking firmware version
04-28 00:26:27.032 D/NativeNfcManager(3199): prev modtime: 0
04-28 00:26:27.032 D/NativeNfcManager(3199): new modtime: 0
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:00.004 W/PackageManager(2383): Unknown permission android.permission.NFC_UNLOCK in package com.android.nfc
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:05.113 W/PackageManager(2383): Unknown permission android.permission.NFC_UNLOCK in package com.android.nfc
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:25.849 I/ActivityManager(2383): Start proc 3199:com.android.nfc/1027 for added application com.android.nfc
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:26.503 I/NfcService(3199): Starting NFC service
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:26.540 I/NFCJNI (3199): NFC Service: loading nxp JNI
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:26.903 I/NfceeAccess(3199): read 3 signature(s) for NFCEE access
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:27.025 D/NfcService(3199): checking on firmware download
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:27.025 D/NfcService(3199): NFC is off. Checking firmware version
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:27.032 D/NativeNfcManager(3199): prev modtime: 0
04-28 00:35:05.401 I/ActivityManager(2383): 04-28 00:26:27.032 D/NativeNfcManager(3199): new modtime: 0

So I enabled Nfc Service, hard rebooted & included a screenshot made using the free MatLog: Material Logcat Reader > Search > nfc. You can see "NFC is off" near the bottom. It does a few things on boot but the Nfc Service is not running in the background.

Conclusion: turn NFC off & leave it alone! :)

Service Disabler and Root Uninstaller are made by the same developer KunKunSoft as the BK Package Disabler 2.3.2 that I am using which has more features (shows Available Memory in the bottom of each panels, export & import list of disabled apps, etc) but it is not in Play Store anymore so I found it on the web somewhere...

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Battery Life?

On my S3 i9300 running Lineage 14.1 + Open Gapps Nano + Lineage super user addon su-14.1-arm, root enabled, with SIM, no custom kernel & no system mods, sync disabled & more than 100 apps installed. As per the attached screenshot of BetterBatteryStats free XDA edition:

- Phone unplugged & left alone for 2 days 52m, battery -11%, average -0.2%/hour. :eek:

That is with Lineage installed as described here: Samsung stock firmware & LineageOS Super Clean Install and optimized as described in S3 Lineage Battery Drain Troubleshooting & Optimization (Thanks to [MENTION=7746932]Robert-R[/MENTION] for linking to it in the post above.)

You can also search this thread for other opinions:

https://xdaforums.com/search/thread/3544531?query=battery life

https://xdaforums.com/search/thread/3544531?query=battery usage

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