Samsung Galaxy S25 Ultra and S24 Ultra Hit by Severe Battery Drain and Overheating After July 2026 Security Update: What’s Going On and What You Can Do

 

By Diablo Tech Blog | July 30 2026 

Samsung’s monthly security patches are meant to fortify Galaxy devices against vulnerabilities while ideally leaving performance and battery life intact—or even improving them. Yet in late July 2026, a wave of complaints from Galaxy S25 Ultra and S24 Ultra owners suggests the latest July security maintenance release (tied to One UI 8.5 builds in many regions) has done the opposite for a noticeable group of users. Reports of dramatic standby battery drain, unexpected overheating during light or idle use, and in some cases slower charging have flooded Samsung Community forums and tech sites.

This is not an isolated grumble. It echoes earlier 2026 episodes of post-update battery issues on the same flagship lines and underscores a recurring pattern that frustrates owners of some of the most expensive Android phones on the market.

The Scale of the Complaints

The core reports center on devices that received the July 2026 security patch. One widely cited Galaxy S25 Ultra owner described a stark change: before the update, battery behavior was normal. Afterward, the phone dropped from roughly 85% at midnight to nearly 5% by midday, despite only about two hours of screen-on time. Idle drain was estimated at 5–7% per hour while the device sat unused.

Similar accounts appear for the S24 Ultra. Users who previously got a full day of solid endurance now report noticeably shorter battery life under comparable usage. Multiple threads on Samsung’s regional community forums (including India, Europe, and others) show users confirming the same symptoms: elevated heat even during basic tasks or standby, and occasional mentions of reduced charging speeds.

These are not fringe posts. Threads fill with “me too” replies, screenshots of battery graphs showing linear drain during long screen-off periods, and Device Care warnings about processes overloading the CPU. Some users note the phone becoming uncomfortably warm during ordinary browsing or messaging, or even while idle. A few report the issue appearing on other recent Galaxy devices as well (including certain foldables) after the same July update window.

Samsung has not issued a public statement acknowledging a widespread problem or confirming a fix at the time of writing. Community moderators typically respond with standard troubleshooting requests (logs via Samsung Members, basic optimization steps) rather than confirmation of a software regression.

What Exactly Changed With the July Update?

The July 2026 Security Maintenance Release is a substantial security package. Samsung’s own bulletin lists dozens of fixes—41 from Google’s Android Security Bulletin (including several critical CVEs) plus 16 Samsung-specific vulnerabilities (SVEs). The focus is hardening rather than feature additions. Rollout began in key markets (starting with Korea for many flagships) and expanded in stages to S25-series, S24-series, and other supported devices. Build numbers vary by region and model (examples include variants in the CZG3 / similar families for S25 Ultra).

Security patches of this size can touch deep system components—power management, background services, Knox-related security layers, connectivity stacks, and more. When something in that chain misbehaves, the symptoms often surface as elevated CPU activity, failed deep-sleep states, or runaway background processes. That matches what users are describing: high idle drain and heat without heavy foreground use.

A Familiar Pattern in 2026

This is not Samsung’s first 2026 battery scare. In April, Galaxy S24 and S25 owners reported severe drain and overheating after that month’s security update. Android Authority and others covered the surge in forum posts; some users pointed to Knox Matrix consuming disproportionate power. Reader surveys at the time suggested a large majority of respondents were affected.

Later in the spring and early summer, One UI 8.5 stable rollouts and subsequent security patches brought fresh waves of similar complaints. Users described post-update “catastrophe” battery life, phones that previously lasted all day now needing midday top-ups, and heat during normal use. Some issues were temporary (the classic Adaptive Battery re-learning period after major updates), while others persisted or required specific workarounds.

Samsung has previously framed some of these as expected short-term optimization after major software changes—the system re-indexes files, recompiles apps, and rebuilds usage models. Adaptive Battery resets mean the phone temporarily treats apps more aggressively until it relearns patterns. In many cases the drain settles after several days or a week of normal use and a few charge cycles. When it does not, the community has learned to dig deeper for stuck processes or buggy system services.

The July reports stand out because the drain is often extreme (multi-percent per hour idle) and appears immediately after the patch, on devices that were otherwise stable.

Possible Culprits

Without official diagnostics, causes remain educated speculation based on user data and past incidents:

• Software regression in power management or security services. A change intended to improve security or fix a vulnerability may keep certain services awake more often, preventing efficient deep sleep.
• Stuck or runaway third-party processes. At least one detailed S25 Ultra case resolved after the user canceled a stuck WhatsApp encrypted backup that was hammering the system in the background. Similar “me too” notes appear in other threads.
• System UI / One UI / core services. Some users report elevated consumption from System UI or related components in battery graphs.
• Carrier- or region-specific interactions. Past patches have shown carrier-variant quirks (for example, Mobile Services issues on certain US networks in earlier 2026 episodes).
• Incomplete post-update optimization. Even security patches can trigger background work that takes time to settle—though the severity described exceeds typical “learning period” behavior for many owners.

Battery health itself is rarely the issue; most reports note 100% health or near-new condition. The problem is software-driven consumption.

Practical Steps Users Are Trying

While waiting for a potential Samsung fix, affected owners have shared a range of mitigations. Results vary:

1. Basic resets and optimization — Restart, run Device Care optimization, put rarely used apps into Deep Sleep, enable Adaptive Battery and Adaptive Power Saving, turn off Always On Display, reduce refresh rate if set to high, disable unused radios (or switch to 4G temporarily in poor 5G areas).
2. Battery stats reset — A community tip circulating for S25 Ultra involves dialing *#9900# (Samsung Phone app), selecting battery stats reset, then restarting. Some advise turning Auto Blocker off first, then back on. Users are told to allow up to 14 days for re-optimization.
3. Check for stuck backups or heavy apps — Inspect WhatsApp (or other messaging apps) for ongoing encrypted backups. Clear cache of high-consumption system apps and Google Play Services. Review battery usage graphs carefully for outliers.
4. Safe mode test — Boot into Safe Mode to see if third-party apps are the main drain source.
5. Cache clearing — Note that some recent One UI versions have removed or restricted the traditional recovery-mode “wipe cache partition” option, limiting this classic fix.
6. Good Guardians / Battery Guardian — Samsung’s optional tools can help identify and restrict problematic behavior for some users.
7. Factory reset (last resort) — After backing up data. This often resolves “dirty” update states but is disruptive.
8. Report thoroughly — Use Samsung Members → Support → Error report with logs, screenshots of battery graphs, and precise build numbers. Volume of quality reports increases the chance of escalation.

Many users report partial improvement after a few days of these steps combined with normal usage; others see little change and are waiting for the next patch.

Broader Implications

Flagship phones like the S25 Ultra and S24 Ultra command premium prices partly on the promise of excellent software support and battery endurance. When a routine security update undermines that endurance for a segment of users—and Samsung remains silent—the trust erosion is real. The pattern of recurring post-update battery complaints across multiple 2026 patches suggests either insufficient pre-release testing under real-world idle and mixed-use conditions, or insufficiently robust power-management regression testing when security changes are applied.

Samsung’s update cadence is aggressive and valuable for security. The flip side is that even small regressions in power efficiency become highly visible on devices whose marketing emphasizes all-day (or multi-day) battery life.

Looking Ahead

As of late July 2026, the most realistic path for affected users is continued monitoring of Samsung Members and official channels for an acknowledgment or targeted fix in a subsequent maintenance release. In the meantime, the workarounds above, combined with disciplined background app management, offer the best chance of reclaiming usable battery life.

If you own an S25 Ultra or S24 Ultra and installed the July security patch, check your own idle drain carefully (compare overnight or multi-hour screen-off periods before and after). Document everything and submit detailed feedback. Collective, high-quality reports remain one of the few levers users have to accelerate a response.

Samsung’s Galaxy flagships remain among the most capable Android devices available. Moments like this, however, highlight that even the best hardware can be undermined by software that doesn’t fully respect the power budget users expect. A prompt, transparent fix—and tighter validation of future security patches against real-world battery metrics—would go a long way toward restoring confidence.