If you're holding onto an iPhone 7 Plus while eyeing newer smartphones like the Galaxy S8 Plus, one frustrating reality might dominate your daily routine: your phone dies by midday. You charge it overnight, yet by lunchtime, you’re scrambling for a power bank. Meanwhile, friends with Android devices—some even from the same era—seem to get through the day without issue. What gives?
The truth is, battery life isn’t just about capacity on paper. It’s shaped by hardware efficiency, software optimization, usage patterns, and most critically, age-related degradation. The iPhone 7 Plus and Galaxy S8 Plus were released within months of each other in 2017, but their long-term battery performance tells very different stories. Understanding why your iPhone struggles now—and how it compares to its Android counterpart—can help you make smarter decisions about maintenance or upgrading.
Battery Capacity and Design: A Technical Comparison
At launch, both phones offered solid battery specs for their time. However, the Galaxy S8 Plus had a clear advantage in raw capacity:
| Device | Battery Capacity (mAh) | Screen Size | Processor | OS at Launch |
|---|---|---|---|---|
| iPhone 7 Plus | 2,900 mAh | 5.5 inches (LCD) | A10 Fusion | iOS 10 |
| Galaxy S8 Plus | 3,500 mAh | 6.2 inches (Quad HD+ AMOLED) | Snapdragon 835 / Exynos 9 Octa | Android 7.0 Nougat |
On paper, the S8 Plus has a 20% larger battery, which should translate to longer endurance. But screen technology plays a crucial role. The S8 Plus uses an AMOLED display, which consumes significantly less power when showing dark content—especially under Samsung’s optimized UI. In contrast, the iPhone 7 Plus uses an LCD panel, which draws consistent power regardless of screen brightness or color.
Apple’s A10 Fusion chip was extremely efficient for its time, often outperforming rivals in tasks per watt. However, iOS updates over the years have added background processes, visual effects, and services that increase strain on older hardware. Android 7 through 9 (the versions supported by the S8 Plus) were relatively lean, especially before Google expanded background syncing and AI-driven features.
Why Your iPhone 7 Plus Battery Dies So Fast Now
Lithium-ion batteries degrade over time. Every full charge cycle wears them down slightly. After two to three years, most users see noticeable decline. By year five—common for iPhone owners—the battery may retain only 70–80% of its original capacity.
Apple acknowledges this. Starting with iOS 11.3, the company introduced **battery health monitoring** and optional performance throttling to prevent unexpected shutdowns on aging iPhones. While controversial, this feature reflects a core truth: as battery capacity drops, voltage instability increases, forcing the system to slow down CPU performance to avoid crashing.
This means your iPhone 7 Plus today isn't just running on a weaker battery—it's also being held back by iOS safeguards designed to keep it functional. The result? Slower performance, reduced responsiveness, and paradoxically, worse battery life because inefficient processing takes longer to complete tasks, keeping the CPU active longer.
“Battery degradation isn’t linear—it accelerates after 400–500 charge cycles, especially if exposed to heat or deep discharges.” — Dr. Lena Park, Battery Research Scientist, MIT Energy Initiative
Real-World Example: Two Phones, Five Years Later
Consider Mark, who bought both an iPhone 7 Plus and a Galaxy S8 Plus in early 2017—one for himself, one for his partner. Both devices were used daily, charged nightly, and updated regularly. By 2022, he noticed stark differences.
The iPhone 7 Plus struggled to last four hours of mixed use. Even after closing apps and reducing brightness, it would shut down unexpectedly at 15%. Diagnostic tools showed a maximum capacity of 72%, and performance management was permanently enabled. Replacing the battery temporarily improved things, but iOS 15 felt sluggish regardless.
In contrast, the Galaxy S8 Plus—despite having no official updates past Android 9—still managed six to seven hours of screen-on time. Its battery health wasn’t perfect, but the phone never throttled itself aggressively. Custom ROMs extended usability, and the AMOLED screen continued to offer energy savings with dark themes.
Mark eventually retired the iPhone first—not because it broke, but because it became impractical. This scenario is increasingly common among long-term Apple users.
Step-by-Step: How to Maximize Your Aging iPhone’s Battery Life
If you’re not ready to upgrade, there are practical steps to extend your iPhone 7 Plus’s daily usability. These focus on minimizing unnecessary drain and improving efficiency:
- Check Battery Health: Go to Settings > Battery > Battery Health. If Maximum Capacity is below 80%, consider a replacement—even third-party options help.
- Disable Background App Refresh: Many apps constantly update in the background. Turn this off for non-essential apps under Settings > General > Background App Refresh.
- Reduce Motion & Visual Effects: Enable Reduce Motion (Settings > Accessibility > Motion) and turn off transparency effects to lower GPU load.
- Limit Location Services: Set location access to “While Using” instead of “Always” for apps like Facebook, Weather, or Maps.
- Use Low Power Mode Daily: Don’t wait until the battery is low. Manually enable it in Control Center to disable mail fetch, automatic downloads, and some visual effects.
- Turn Off Push Email: Switch to Fetch manually or every hour instead of constantly checking servers.
- Keep iOS Updated (But Not Too Late): Security patches matter, but avoid upgrading to the latest iOS version if your device feels slow. Sometimes staying one version behind improves stability.
Checklist: Preserve Your iPhone’s Remaining Battery Health
- ✅ Avoid charging to 100% daily; aim for 20%-80% when possible
- ✅ Remove thick cases during charging to prevent overheating
- ✅ Disable Raise to Wake (Settings > Display & Brightness)
- ✅ Turn off Bluetooth and Wi-Fi when not in use
- ✅ Use Airplane Mode in low-signal areas (phone boosts power searching for towers)
- ✅ Delete unused apps that run background processes
- ✅ Enable Auto-Brightness to reduce screen power waste
Frequently Asked Questions
Can I replace the iPhone 7 Plus battery and expect like-new performance?
Yes—replacing the battery can restore 95–100% capacity and disable performance throttling. Apple offers official replacements, and many third-party shops provide affordable options. After replacement, reset settings and recalibrate by fully charging and draining once.
Is the Galaxy S8 Plus really better than the iPhone 7 Plus for long-term battery use?
In real-world longevity, yes—for different reasons. The S8 Plus started with a larger battery and more efficient display tech. Samsung also applied fewer aggressive throttling measures, allowing sustained performance even as the battery aged. However, lack of modern security updates makes it risky for primary use today.
Why does my iPhone die at 20%?
This usually indicates advanced battery wear. The phone’s battery gauge becomes inaccurate as cells degrade. It may report 20% when voltage suddenly drops below operational levels, causing an abrupt shutdown. A battery replacement resolves this in most cases.
Conclusion: Respect the Lifespan, Then Move On
Your iPhone 7 Plus served you well. It delivered smooth performance, excellent cameras, and seamless integration with the Apple ecosystem. But all batteries degrade, and software demands grow. Holding onto a device beyond its effective lifespan leads to frustration—not because you’re using it wrong, but because physics and engineering have limits.
Understanding the difference between the iPhone 7 Plus and Galaxy S8 Plus isn’t just about specs—it’s about how design choices affect longevity. Apple prioritizes tight integration and controlled updates; Samsung leaned into hardware flexibility and display efficiency. Both approaches have trade-offs.
If you’ve followed best practices and still can’t make it through the day, it’s not you—it’s time. Whether you choose to repair, recycle, or upgrade, do so knowing you got value from a device that helped shape mobile computing. And next time, monitor battery health early, act before it’s too late, and plan for the inevitable: batteries don’t last forever.
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