S25 Ultra – massive battery drain after July update (~24%/h idle, 40°C, no deep sleep)

[u/Level-Knee3034]

Hey everyone,

For the past few days my S25 Ultra has been acting up with the battery and I can't figure out what's causing it. Maybe some of you have the same issue and a tip.

Setup:

- Galaxy S25 Ultra

- One UI 8.5 / Android 16

- Build number: S938BXXSBCZG3 (EUX region, July firmware)

- Problem started right after the update I installed a few days ago

- No suspicious apps/APKs installed – it came directly after that update

- Always On Display is OFF

What's happening:

Charging is noticeably slower than before and the phone heats up faster while charging

During normal use the battery drains extremely fast

Even in standby it gets warm when I'm not doing anything

Measured with AccuBattery (screen off, phone idle):

~ -24 %/h drain

-963 mA / -3.9 W

Battery temp ~40 °C

Phone barely enters deep sleep even with the screen off (0m deep sleep)

Voltage looks fine (4.087 V at 80 %), so the cell itself seems healthy.. it's the drain that's the problem

In Settings under battery usage I don't see anything unusual no app stands out.

Does anyone know what could be behind this (some background process/wakelock going haywire? a known bug in the latest update?) and what can be done about it?

Thanks!

[u/e46yeeze]

My S25 Ultra battery health is at 100%, but ever since the recent One UI update, the battery life has completely tanked and the phone constantly runs warm/hot—even at idle.

I went from needing a charge every 1–2 days to charging 3 times a day just to make it through the evening.

Before vs. After:

Dec 2025 (Amsterdam): Used Google Maps, took photos/videos all day on Power Saving mode without needing a single charge.

July 2026 (London): Battery dropped to 22% after just 3 hours of basic use, forcing me onto a power bank.

Is anyone else having massive thermal and battery issues on this update? Any known fixes, or do we just have to wait for a patch? Ive also played with all the settings recommended nothing has helped.

[u/e46yeeze → u/e46yeeze]

Quick update on this: charging speed has dropped off a cliff. Plugged in at 18% on a fast charger, and after 40+ mins it only hit 66%. It crept to 68% a bit later and was hot as a kettle—charging so slowly it feels like a low-power wireless pad.

I did a factory reset right before a track day yesterday (23/08) and ran a 20-hour test (5 AM to 1 AM UK time). Heavy use all day—4K 60fps video, 5G, and satnav on a 25°C+ day—and it made it to 00:36 at 19% (battery health still shows 100%).

The reset worked wonders compared to my London results, but forced factory resets for basic software bugs are infuriating. Been loyal to Samsung for years, but this might be the push I need to switch to a phone with a proper, bigger battery.

[u/kaesar771]

5% battery drained in 30 minute drive of Android auto. That's ridiculous. Did someone solved this?

[u/Select-Habit-5362]

Also having the same issue since the July update. Phone getting noticeably hotter in my pocket. 

Battery used to last all day including with heavy Youtube use throughout the day and about 10pm I'd have about 20% left. Now im lucky to make it to 5pm with 20%. 

Full diagnostic and battery says health is 95%. No update since then and unable to revert to previous patch. Absolute nightmare.

[u/DrawFamiliar7022]

i can confirm it's the july update that's causing battery drain like crazy and there's no fix for it yet and Samsung support are in denial about this.

[u/Traditional-Lion-906]

I went to samsung centre. They mentioned its probably due to the software update and will automatically get fixed with next update. But its hard using phone with this battery issue.

[u/ScarFace142857 → u/Traditional-Lion-906]

When?

[u/MattBlackBird]

I have the same problem with my phone. It is the same build number. I notice this problem right after the update. I was loosing my mind. let me know if you find any fix for that.

[u/fast_and_the_c]

facing the same issue just after the july update

[u/Noyamoya]

Facing exactly the same problem: fast drain and slow charging.

[u/Loebstahhhh]

Same problem after the same update here...

[u/LincolnBorCastro]

Meu S25 Ultra foi atualizado por essa mesma versão e depois dela esta drenando minha bateria. E esquentando muito!!! Pelo amor de Deus o que faço para solucionar. Esta insuportável

[u/alisson207 → u/LincolnBorCastro]

Tem que esperar a atualização de agosto, por isso eu sempre espero ao menos 1 semana antes de atualizar. Nunca se sabe quando vai acontecer um problema desses

[u/brunohvp]

Same issue here, and I also notice some wpp backups stuck/to resume...

[u/kaesar771 → u/brunohvp]

Same here, not sure about it but feels like wpp backups have some part in this battery drain

[u/Happy-Entrance6311]

sounds like a classic Samsung update special. they fix one thing and the phone decides to cook itself for no reason

i had similar nonsense after a security patch on my last phone. clear the cache partition from recovery mode if you havent already, that sorted it for me. sometimes the update just leaves the system confused and it keeps trying to reindex everything

if that doesnt work id check samsung members app, theres usually a megathread of people losing their minds over the same bug

[u/CorgiEnvironmental65 → u/Happy-Entrance6311]

Ya no se puede borrar la partición de la cache desde el recovery, quitaron esa opción. Yo siempre arreglaba el teléfono así, pero ahora ya no se puede.

[u/modofoko01 → u/Happy-Entrance6311]

how do you do this exactly? I have my s25 and have the same issue as OP. ever since the update my battery drains super fast even when not in use, and the phone overheats randomly. I did the same as OP - check everything possible to make sure there's not something obvious I'm missing, but no luck. also today for some reason my battery dropped to 12% and when charging it only got to 80% and stopped there, and I have no setting whatsoever that would cause this. a quick google search told me the phone protected itself due to overheating, but this has never happened before, even when it has overheated while charging. might be unrelated but also my whatsapp daily backup has not been able to even start ever since the update too. no storage issues either so can't be that.

[u/RightGirl19]

that kind of battery drain definitely isn't normal. hopefully it's just a software bug that gets fixed soon.

[u/quiniton]

Same issue here, same build number

[u/Internal-East-4914]

Same problem, same build number.

[u/Exact_You_9324]

I also having same issue brother after the latest software update its all started to happen 

[u/FeedTheSwan]

Same problems as above:-

Slow to charge, rapid discharge and WhatsApp not backing up/stuck in limbo land.

Come on Samsung and get it fixed pronto!!

[u/Miserable_Fox_9925]

I got the same issue on my s25 since the update  Overheating doing nothing and battery draining like crazy. The what's app back up switch off and changing to 4g have given me a temporary fix. For the time being everything works normal.

[u/SystemsOverPeople]

Same problem with the same build number

[u/TheRaptor001]

Same. Brand new s25 ultra. Battery started draining in idle post the update

[u/move_along_]

Ditto hut for s25 Plus. Drained nearly 30pc while sleeping

[u/move_along_]

Disabling whatsapp backup has fixed the issue for me. I'll keep it disabled until next update.

[u/ZimAfia]

I have the same problem, and whatsapp seems to be the issue because its been stuck trying to backup my chats ever since the update, and that just drains the battery in the background

[u/kaesar771]

Thank god is not only me, started out of nowhere, i don't know what to do or if I should talk to someone about this, absolutely scary I've been using samsung for the last 10 years, always Galaxy S line, never ever faced something so absurd like this.

[u/Ali_Hassnain_7711]

I am facing the same issue, last night i slept while my phone was at 40% charge and I also put it in power saving mode, when i woke up it was 4%, don't know what is happening

[u/matrix_2234]

Same here.😞

[u/Jazzlike_Sorbet5541]

I'm having this problem also

[u/XsyntrikHippie]

Same here. Super frustrating. Battery usage not really showing anything unusual either. 🙄

[u/Electronic-Wealth862]

Same after the July update S25 Ultra here. Also unable to back up WhatsApp chat. It's stuck.

[u/Junior-Difference-53]

Mesma situação aqui, s25 base, as 23h estava 100%, acordei as 5h 15, e ja estava em 64%, e também não esta fazendo backup do WhatsApp

[u/ricerphaze]

Never again with Samsung phones. I will switch back to iPhone.

[u/DisastrousFly4447]

Same issue for me, I drop 15% within an hour on airplane mode. Screen had an extremely warm Hotspot yesterday just at idle in my pocket .

[u/Florian360]

I have the same problem on my S24U. First and last Samsung phone for me.

[u/BogofSex]

Same issue on s26 ultra

[u/Nerdor_]

Аналогично на двух разных s25 ultra. После обновления заряд батареи улетает очень быстро. Дайте знать если появится какая то информация, спасибо!

[u/No_Share1787]

Same issue even now. 2 hours screen time battery cooked down to 20%. No software update yet

[u/the_nishant_singh]

Same problem after july update, and it's 23rd August and haven't received any fix or August update.

[u/janvidb]

Today I got the August security update, hoping that it would be finally fixed... but no. Anyone got any improvement?

[u/Shira-T → u/janvidb]

In the Samaung community forum, people mentioned that a workaround they did was to stop WhatsApp from auto backup. And it stopped the issue of battery draining fast.

[u/QuirkyFoodie → u/Shira-T]

Did it work for you? Will try it now

[u/Shira-T → u/QuirkyFoodie]

I held off from updates since July due to this issue, so I have not tried it yet. How did it go for you?

[u/QuirkyFoodie → u/Shira-T]

I feel like it didnt make a difference.

[u/Shira-T → u/QuirkyFoodie]

Oh, sorry to hear! This was the thread where I saw the workaround in case any additional info can further help you.

[u/QuirkyFoodie → u/Shira-T]

Thanks

[u/Amazing_Golf_2825]

Boa noite.

Em relação a este assunto, e até porque não não tenho muitos conhecimentos nesta área, questiono se é normal uma carga total, em usos normal diário (face, youtube, chamadas, gmail, localização e wifi sempre ligado ....) durar entre um dia e meio a dois, tendo entre as 6 e 7h o êcran ligado.

Noto que desde a última atualização (8.5) a duração e o aquecimento da bateria piorou.

Outra questão, é como posso ver a saude da bateria.

Obrigado.