iPhone 15 vs iPhone 14 Battery Test

Battery Capacities: The Starting Point
The fundamental hardware specification for any battery test is the raw capacity, measured in milliamp-hours (mAh). The iPhone 14 housed a 3,279 mAh battery. The standard iPhone 15 sees a modest increase to 3,349 mAh. The larger Pro models show a more interesting shift. The iPhone 14 Pro contained a 3,200 mAh battery, while the iPhone 14 Pro Max featured a 4,323 mAh unit. For the iPhone 15 Pro, Apple actually reduced the capacity slightly to 3,274 mAh. Conversely, the iPhone 15 Pro Max received a significant upgrade, boasting a 4,422 mAh battery—the largest ever in an iPhone. This sets the stage for a nuanced battle where software and silicon efficiency become as important as raw power.

The A16 Bionic vs. The A17 Pro: Efficiency Under the Microscope
The core of the battery life conversation revolves around the system-on-a-chip (SoC). The iPhone 14 and 14 Plus utilize the A15 Bionic, while the iPhone 14 Pro models introduced the A16 Bionic. The entire iPhone 15 line, however, is powered by a new generation of processors. The standard iPhone 15 and 15 Plus use the A16 Bionic (now a year old), and the Pro models debut the new A17 Pro chip, built on a cutting-edge 3-nanometer process.

This 3nm architecture is pivotal. It allows for a significantly higher transistor density, which translates to either more performance at the same power draw or the same performance at a lower power draw. Apple claims the A17 Pro’s efficiency cores are up to 3x more efficient than the competition, but the real-world test is against its predecessor. In sustained tasks, the A17 Pro’s advanced manufacturing should, in theory, lead to better power management and less thermal throttling, thereby preserving battery life during intensive workloads like gaming or video editing.

Display Technology: Always-On and Dynamic Island
The iPhone 14 Pro models introduced the Always-On Display (AOD) and the Dynamic Island, both of which have implications for power consumption. AOD, while cleverly designed to drop its refresh rate to just 1Hz, still requires constant power to illuminate pixels. The iPhone 15 Pro models retain these features, but with potential software optimizations in iOS 17 that may slightly refine their power draw. The standard iPhone 14 and 15 models, lacking AOD, avoid this constant drain entirely, which inherently benefits their standby battery performance.

Methodology: Simulating Real-World Usage
A comprehensive battery test moves beyond a single metric. Reputable testing involves a controlled, standardized set of tasks designed to mimic average user behavior. Common methodologies include:

• Web Browsing Test: Continuously loading complex web pages over Wi-Fi, stressing the CPU and modem.
• Video Playback Test: Streaming video (e.g., via YouTube or a local file) at a fixed brightness level (often 200 nits), testing the display and media decoding efficiency.
• 3D Gaming Test: Running a graphically intensive game, which maximally stresses the GPU and CPU, generating heat and high power draw.
• Standby Test: Measuring drain over 8-24 hours with the phone idle, testing background process management.

Test Results: A Model-by-Model Breakdown

• iPhone 15 vs. iPhone 14: Given that both models share the same A16 Bionic chip and nearly identical form factors, the small ~2% increase in battery capacity of the iPhone 15 results in a marginal improvement. In most tests, the iPhone 15 will last approximately 30 minutes to an hour longer than the iPhone 14 under identical conditions. This is a slight but welcome gain for a direct successor.

• iPhone 15 Plus vs. iPhone 14 Plus: This comparison is similar to the standard model matchup. Both devices use the A16 Bionic and have large physical footprints that allow for big batteries. The iPhone 15 Plus benefits from its slightly larger cell and potential incremental efficiency tweaks, often edging out the 14 Plus by a similar margin of about an hour in continuous use tests. Both models consistently rank as the overall battery life champions in the iPhone lineup.

• iPhone 15 Pro vs. iPhone 14 Pro: This is the most complex and surprising comparison. The iPhone 15 Pro has a slightly smaller battery (3,274 mAh vs. 3,200 mAh) but a more advanced 3nm A17 Pro chip. Test results are mixed and highly dependent on usage. In light-to-moderate tasks like web browsing, social media, and video playback, the efficiency of the A17 Pro often allows the iPhone 15 Pro to match or very slightly exceed the battery life of the iPhone 14 Pro. However, under sustained heavy load—such as extended 4K video recording or high-frame-rate gaming—the A17 Pro’s performance cores can draw more power, potentially causing the 15 Pro to drain slightly faster than its predecessor in these specific, intensive scenarios. Thermal throttling can also play a role if the device gets too hot.

• iPhone 15 Pro Max vs. iPhone 14 Pro Max: Here, the narrative is clearer. The iPhone 15 Pro Max combines the efficiency of the A17 Pro chip with the largest battery ever in an iPhone (4,422 mAh). This combination delivers a definitive and noticeable improvement in battery life over the already-excellent iPhone 14 Pro Max. Across virtually all test categories—web browsing, video playback, and especially standby time—the 15 Pro Max consistently lasts longer, often by a significant margin of 2-4 hours in total usage time. It sets a new benchmark for iPhone endurance.

Charging and Connectivity: The USB-C Factor
A critical change across the entire iPhone 15 series is the transition from Lightning to USB-C. This does not inherently change charging speeds—the iPhone 15 and 15 Pro still max out at around 20-23W with a compatible USB-C Power Delivery charger, similar to the iPhone 14 series. The iPhone 15 Pro Max can accept slightly higher peak wattages (approx. 27W) for marginally faster top-ups. The true battery-related benefit of USB-C is convenience and universality, reducing the need for multiple cables. Furthermore, the iPhone 15 series supports faster data transfer speeds on the Pro models, but this has a negligible impact on overall battery consumption for the average user.

Practical Implications and User Experience
For a user upgrading from an iPhone 13 or older model, any iPhone 14 or 15 will offer excellent battery life. The choice between generations should be based on more than just battery performance. The standard iPhone 15 models offer the Dynamic Island and a superior 48MP main camera, making them a more significant upgrade over the iPhone 14 than the battery test alone suggests.

For Pro users, the decision is nuanced. If maximizing battery life is the absolute priority, the iPhone 15 Pro Max is the undisputed king. The smaller iPhone 15 Pro offers a more modern chipset and features but delivers largely similar—and in some heavy-use cases, slightly less—battery endurance than the iPhone 14 Pro. Most users will not notice a dramatic difference day-to-day between these two Pro models.