What fast charging claims really mean in daily use
Fast charging is the process of sending higher-than-standard power through a compatible charger and cable so a phone battery can move from empty to a usable level of charge far more quickly than with basic chargers, though the real charging pattern varies over time and rarely matches the headline wattage figure. To see how that plays out in practice, we ran a fast charging speed test on three flagship phones: iPhone 17 Pro Max, Samsung Galaxy S26 Ultra, and OnePlus 15. Each phone was tested twice—once with its own charger and cable, and once with an Anker Prime GaN charger and Anker bio cable. We tracked real-time power draw using a Mecheer power meter to compare real vs advertised charging across the full charge cycle, from 0% to 100%. The goal was a realistic flagship charger comparison rooted in measured data, not marketing.
Inside the test bench: tools, plugs, and batteries
Each phone entered the test at 0% battery and stayed connected until it fully charged, providing a consistent way to compare phone charging claims. The iPhone 17 Pro Max uses a 5,088 mAh lithium-ion battery with up to 40W wired charging, while the Samsung Galaxy S26 Ultra carries a 5,000 mAh lithium-ion battery rated at 60W. OnePlus 15 stands out with a 7,300 mAh silicon carbon battery and an advertised 120W charging speed. A Mecheer power meter displayed live wattage, revealing how power climbed and fell over time. The iPhone and Samsung relied on separately purchased OEM chargers—Apple’s 40 W Dynamic Power Adapter for USD 39 (approx. RM180) and Samsung’s 45W travel adapter with magnetic wireless puck for USD 71.25 (approx. RM330)—plus the Anker Prime GaN charger and Anker bio cable, while OnePlus 15 used its in-box plug and the same Anker setup for the second run.
Real vs advertised charging: where the numbers diverge
The graphs exposed a clear gap between real vs advertised charging speeds. OnePlus 15, which promotes 120W charging, never came close to that on the meter. According to ZDNET’s Adam Doud, “OnePlus’ charger isn’t even close to its advertised 120W speed…maxing out at just 46W on its homegrown charger.” During most of the session, it hovered in the 20% to 40% power range. Meanwhile, Samsung’s 60W rating proved conservative: the Galaxy S26 Ultra peaked at 61W, slightly above its spec, and completed a 0–100% charge in under an hour. The iPhone 17 Pro Max, rated at 40W, spent its first five minutes above that threshold before settling down. These patterns show that headline wattage is more of a momentary peak than a sustained promise, especially once the battery passes its initial low-charge phase.
OEM vs Anker: how much the charger really matters
Swapping chargers changed the flagship charger comparison in ways that may surprise many buyers. The Anker Prime GaN charger, paired with Anker’s bio cable, outperformed more than one official charger. According to ZDNET, the Anker pairing charged the OnePlus 15 and Samsung Galaxy S26 Ultra faster than their own OEM plugs, despite those plugs being designed and marketed for their specific phones. That does not mean brand-name chargers are useless; they still ensure compatibility and follow safety standards. But it shows that a high-quality third-party charger can improve effective fast charging speed, especially when a phone does not include a plug in the box. As with fast power banks tested in the lab, where charging milestones vary by setup, wall power, and overhead, the power source and cable you pick can noticeably shift your real-world results.
What buyers should look at beyond the wattage number
For everyday users, the lesson from this fast charging speed test is simple: focus on how long it takes to reach usable levels rather than chasing the biggest watt number. OnePlus 15’s bold 120W label did not translate into record-breaking real-world charging, while Samsung’s 60W-capable S26 Ultra quietly finished a full charge in less than an hour. In the same way ZDNET’s power bank tests measure time to 50%, 80%, and 100% instead of trusting indicators, phone buyers should ask how long it takes to hit 50% or 80% in normal conditions. Look for independent testing that compares phone charging claims to measured performance and pay attention to which charger and cable were used. If you match a reputable third-party charger with your flagship phone, you can get closer to the performance the marketing suggests, and avoid disappointment.
