S21 battery draining very quickly

[Alrocsmash]

Howdy folks,

My S21, current OS patch version, randomly started overheating and battery draining very quickly last week. This was an abrupt change in behavior. I factory reset my phone. That fixed it for a few days and then this issue reappeared. I cleared my partition cache, no change. I swapped my battery for an OEM battery at a shop. No change. Accubattery and Devcheck both say no app is draining any CPU, RAM or power unnecessarily. This has to be a droid OS issue. Apparently late last year around One 6.0 some bad stuff happened and I have now been affected and cannot find any resolution. My phone now has to be on a charger 24/7 for normal use. The heat alone will end of life the device prematurely. Totally unacceptable.

Help? Much appreciated.

[MrBond007]

Looks like, so far, the problem may have gone away for me. Used the phone for 20 minutes today, disconnected for almost 2 hours from charger, 5% used. Would have been down 25% yesterday by now. No longer warm, I have done nothing to the phone.

[Alrocsmash]

Same. As of yesterday, my phones battery performance returned to normal. They probably stealth patched something without forcing an actual OS update, for legal reasons aka the S8 battery exploding issues they had.

So I googled the ***** out of this, missing a decimal on how to charge lith ion cells by even a few mA can blow up cells. While this is just one nerd typing on the internet, this is likely the case and they fixed it. Glad my phone didn't blow up in the process.

[MrBond007]

Mine has started doing it again it looks like, down 20% after 1 hour being unplugged, warm, and running slow.

CPU usage, across all cores is at 50 - 70% constantly.

[Alrocsmash]

Yup. Same issue returned here as well. And agree on the CPU usage, I missed that the first time around. I thought that was standard background CPU usage but in the last 2 weeks when the issue went away, prob 10% background usage. This is a CPU leak in code somewhere.

Samsung - Respond please.

[MrBond007]

This is my current process list for the phone and whats using CPU:

Tasks: 845 total,   3 running, 842 sleeping,   0 stopped,   0 zombie
  Mem:    10575M total,     9133M used,     1441M free,        4M buffers
 Swap:     8191M total,      962M used,     7229M free,     4150M cached
800%cpu 289%user  47%nice 179%sys 269%idle   1%iow  12%irq   2%sirq   0%host
  PID USER         PR  NI VIRT  RES  SHR S[%CPU] %MEM     TIME+ ARGS                                                                                                                           
 1412 system       18  -2  25G 476M 243M S  148   4.4  24:52.47 system_server
  959 statsd       20   0  12G 8.0M 3.8M S 94.3   0.0  11:14.21 statsd
 3960 u0_a121      20   0  16G 174M  92M S 77.0   1.6   1:02.26 com.samsung.android.scs
23189 u0_a383      20   0  16G 243M 125M S 29.0   2.2   0:47.43 com.microsoft.windowsintune.companyportal:omadm_client_process
24498 u10_a383     20   0  32G 188M 117M S 27.3   1.7   6:59.91 com.microsoft.windowsintune.companyportal:auth
  629 logd         30  10  12G 108M 3.4M S 16.0   1.0   2:52.61 logd
 8535 u0_a290      16  -4  17G 220M 137M S 14.0   2.0   0:13.71 com.microsoft.office.outlook
 4312 u10_a251     20   0  16G 221M 151M R 13.3   2.0   3:36.33 com.google.android.gms.persistent
32285 u10_a249     20   0  16G 131M  76M S 12.0   1.2   3:36.86 com.google.android.apps.restore
 2049 u0_a62       20   0  18G 392M 234M S  9.6   3.7   0:37.84 com.android.systemui
23098 u10_a251     20   0  17G 239M 158M S  9.3   2.2   1:57.11 com.google.android.gms
18507 u0_a349      20   0  16G 158M  96M S  6.3   1.4   0:24.14 com.Slack
 3363 u10_a264     20   0  16G 107M  68M S  4.3   1.0   0:55.48 com.google.android.syncadapters.calendar
  142 root         20   0    0    0    0 S  3.6   0.0   0:40.85 [kzerod]

[MrBond007]

I had posted, not too long ago, my process list on the phone, obtained via adb, but it got deleted as spam it looks like for some reason. But the top 3 processes that took up over 300% CPU (3 cores) were:
system_server
statsd
com.samsung.android.scs

[Alrocsmash]

I rebooted my phone just now, and it's back to normal. Give it a try, this is a friggin' roller coaster man.

[MrBond007]

I didn't need to reboot, cpu usage just reduced without doing anything:

Tasks: 886 total,   1 running, 885 sleeping,   0 stopped,   0 zombie
  Mem:    10575M total,    10219M used,      356M free,        3M buffers
 Swap:     8191M total,     2199M used,     5992M free,     3557M cached
800%cpu  30%user   2%nice  43%sys 711%idle   0%iow  10%irq   5%sirq   0%host
  PID USER         PR  NI VIRT  RES  SHR S[%CPU] %MEM     TIME+ ARGS                                                                                                                           
 1412 system       18  -2  25G 445M 214M S 12.0   4.2 434:27.02 system_server
32600 root          0 -20    0    0    0 I  8.3   0.0   0:50.70 [kworker/u17:2-bcm477x_wq]
 5077 u0_a290      20   0  34G 446M 274M S  7.3   4.2   6:46.87 com.microsoft.office.outlook
11295 u0_a5        20   0  38G 360M 243M S  7.0   3.4   0:25.72 com.insideinc.gcpu
10635 u0_a349      20   0  17G 108M  60M S  7.0   1.0   5:37.20 com.Slack
 1101 system       -3  -8  13G  36M  19M S  7.0   0.3  42:23.01 surfaceflinger
  984 system       20   0  12G 2.6M 2.1M S  5.6   0.0  10:15.51 android.hardware.sensors@2.0-service.multihal
22796 u0_a259      20   0  33G 224M 151M S  3.3   2.1   1:40.70 com.android.chrome
 2049 u0_a62       20   0  18G 408M 199M S  2.6   3.8  16:13.97 com.android.systemui
  267 root         20   0    0    0    0 S  2.3   0.0   2:18.26 [spi7]
 8308 u0_a303      20   0  18G 101M  49M S  2.0   0.9  12:55.69 com.sec.android.app.shealth:remote
  646 root         RT   0    0    0    0 S  2.0   0.0   5:11.65 [esgov:0]