iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
You can’t tell how long an 8,340 mAh phone battery will last from capacity alone. To find out whether it lasts longer than another phone—or longer after a change—compare the exact devices under the same workload and conditions, and measure elapsed time to the same stopping point. The capacity figure does not identify a particular handset, so it cannot support a device-specific verdict.
What “lasts longer” needs to mean
First name the comparison: two specific phones, or the same phone before and after a change. Record the exact model names and regional variants. A capacity rating is not a runtime result, and the title does not identify a handset or comparison target.
Next choose a workload. A mixed-day test can include calls, web browsing, video streaming, and gaming or navigation if those are part of your routine. If you mainly want to know how long a phone plays video, test video alone and label the result as a video playback comparison—not general battery life.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Brightness, refresh rate, network type and signal, background activity, temperature, battery age and health, and workload can all affect runtime. For example, PhoneArena’s battery test methodology specifies 200-nit brightness, Wi-Fi, new-device battery health, and current firmware for its tests, while warning that signal, temperature, and aging affect real-world results. GSMArena’s methodology also identifies network environment, background processes, ambient temperature, and ambient light as factors.
#1 Best Overall
- Up to 3.5 Phone Charges On the Go: Compact and easy to carry, this 15,000mAh power bank keeps you powered for travel, commuting, and emergencies. Charges iPhone 17 up to 3.5 times, Samsung S26+ up to 2.5 times, and AirPods Pro up to 20 times.
- 40% Smaller, 45% Lighter: Designed for power without the extra bulk, this compact power bank is 40% smaller and 45% lighter than conventional models, making it easy to carry for travel and daily use. Built-in USB-A, Type-C, iOS, and Micro cables keep your devices ready to charge—no extra cables needed.
- Airline-Safe Power, Trusted Worldwide: Safe charging you can trust. Join over 50 million users worldwide who rely on our safety-focused design for worry-free charging and carry-on travel.
- 50% Power in 30 Minutes: Get fast, convenient charging when you need it most. This 22.5W portable charger powers your phone up to 50% in just 30 minutes, ideal for busy days and travel.
- Charge 6 Devices at Once: With 6 outputs and a bi-directional Type-C port, this portable charger powers multiple devices at the same time. Compact enough for your pocket or bag.
Run a repeatable comparison
This is a practical procedure for making a fair comparison, not a formal universal standard. Keep conditions as similar as you reasonably can and record any differences.
- Choose the workload and endpoint. Write down the apps, content, duration, and order for each activity. Decide in advance when to stop—for example, at 20% remaining or at shutdown. A 20% endpoint compares partial discharge; it does not measure total runtime from full to empty.
- Match starting conditions. Fully charge both phones and let them settle. Begin each run at the same charge level. Use the same brightness setting and refresh-rate policy, and connect to the same Wi-Fi or cellular network in the same location. Keep temperature and background activity as similar as practical.
- Keep the test stable. Use the same apps and content for each phone, and avoid installing updates or changing settings between paired runs. If a condition differs—such as a weak cellular signal—note it rather than treating the result as directly matched.
- Log the result. Start the workload at the chosen charge level. At fixed intervals, record elapsed time, remaining battery percentage, and screen-on time until the endpoint. Use the phone’s battery display and a timer.
- Repeat comparable runs. A single result can be affected by changing conditions. Repeat the comparison on multiple similar runs and report the range or median, along with the workload and stopping point.
Check what a normal day looks like
A controlled comparison helps isolate differences, but it may not resemble your own routine. For a personal-use check, keep a short log over several ordinary days. Record starting and ending charge, screen-on time, broad activity mix, Wi-Fi or cellular use, and unusual conditions such as weak signal or extended navigation. Compare similar days; daily activity varies, so treat this as your usage record rather than a laboratory result.
Rank #2
- Ultra-Slim & Light weight Design: At just 0.63 inches thick and 8.11oz, this is the slim and light 10000mAh power bank. Perfect for travel, it easily fits in your pocket or bag without adding bulk.
- 22.5W USB-C Fast Charging: Equipped with USB-C input and output, this power bank supports PD3.0 and QC4+ fast charging, delivering up to 22.5W of power. Charge your iPhone to 65% in just 30 minutes or power up multiple devices quickly.
- 3 Output & Dual Input: Features 3 outputs (2 USB-A + 1 USB-C) and 1 inputs (USB-C ), allowing you to charge up to three devices simultaneously. Ideal for smartphones, tablets, earbuds, and more.
- Wide Compatibility: Works seamlessly with a wide range of devices,Compatible with iPhone 17/16/15/14/13/12, Samsung Galaxy, Google Pixel, iPads, AirPods, Android tablets, and other USB-C devices.
- Advanced Safety & LED Display: Built with an 8-Layer Protection System to prevent overcharging, overheating, and short circuits. The LED digital display shows the remaining battery percentage, so you’re never caught off guard by a low battery.
Use published battery tests without mixing unlike scores
Published tests are useful for controlled comparisons, but they do not guarantee the same result in your routine. Check the test workload, conditions, and version before comparing a score with another publication’s result—or with an older score from the same publication.
Recommended Free Tools
| Source and method | What it measures | How to interpret it |
|---|---|---|
| GSMArena Battery Life Test 2.0 | Calls over 4G/VoLTE, web pages with scrolling and touch input, YouTube streaming, and a looping 3D game. Its Active Use Score estimates a balanced mix, with slight emphasis on web and video; users can adjust the assumed mix. | GSMArena discontinued its former Endurance rating when it introduced Test 2.0. Do not treat an older Endurance score and a newer Active Use Score as interchangeable. |
| GSMArena legacy battery table | The Endurance figure models one hour each of calls, video, and web browsing per day, plus standby; sliders let users customize those components. | Use it to understand the old figure’s assumptions, not as a renamed Test 2.0 result. |
| PhoneArena battery benchmarks | Separate scripted browsing, streamed video, and gaming tests. The page specifies 200-nit brightness, Wi-Fi only, 100% battery health, latest firmware at test time, and new devices in controlled labs. | Compare individual use-case results where possible. The page warns that real-world results vary with signal strength, temperature, and battery aging. |
| Tom’s Guide 2026 guide | A scripted web-browsing test using the default browser and 150-nit brightness. It tests default refresh settings and may also test alternate refresh rates. | The guide says newer reviewed models were tested with an updated version. Check a phone’s test version before comparing its score with another result. |
Tom’s Guide’s 2026 guide reports nearly 11 hours as the average smartphone runtime in its web-browsing test; that is not a universal real-world average or a prediction for an unidentified 8,340 mAh phone. Its list of longest-lasting phones generally requires results approaching 16 hours, a threshold for that publication’s test and list—not a general standard.
Rank #3
- Universal 5V Battery Pack for Heated Clothing: Compatible with 5V heated jackets, vests, and trousers. This upgraded battery pack offers steady, reliable warmth, keeping you comfortable through any cold-weather activity.
- Pocket-Sized Portability: At only 5.5" x 2.6" x 0.5" and just 0.5 lbs, this slim, lightweight battery is built to go anywhere. Its compact design fits easily in your pocket, so you can stay powered and comfortable wherever the day takes you.
- High 10,000mAh Capacity: Reliably charge most smartphones 2-3 times or a tablet once, providing ample power for a full day out or during travel.
- Triple-Port Fast Charging: Two USB-A ports and one USB-C port allow you to charge up to three devices at the same time. Whether you're powering a phone, tablet, earbuds, or other small devices, you get fast, convenient charging without waiting for an available outlet.
- Comprehensive Safety System: Features advanced protection against over-charging, over-discharging, over-current, over-voltage, and short circuits for safe charging of all your connected devices.
What to record when comparing published results
- Exact phone model and regional variant
- Battery age and health
- Benchmark publisher and test version
- Workload category and duration
- Brightness and refresh-rate setting
- Network type and signal conditions
- Elapsed runtime, including the same starting charge and stopping point
If any of these differ, the results may still be informative, but the difference should be visible in your comparison rather than hidden behind a single battery-life number.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
