What “fast charging” really means in the real world
Fast charging test results describe how quickly a phone or power bank can move from empty to specific charge levels under controlled conditions, revealing real-world charging performance instead of relying on marketing watt numbers alone. When brands advertise 40W, 60W, or even 120W charging, they are not saying your phone will draw that power all the time. In practice, charging is a curve: power ramps up, holds for a short window, then tapers off to protect the battery and manage heat. That is why two phones with similar wattage claims can show very different phone charging speed from 0% to 100%. It is also why accessory testing matters. As ZDNET’s lab notes for power banks, measuring energy drawn from the wall at specific milestones gives a more honest view than trusting on-device indicators or spec sheets.
Inside the test bench: methods that expose the real numbers
Real-world charging performance depends as much on testing discipline as on the phone or charger itself. ZDNET’s power bank lab used a HOBOware plug load logger and a 70W USB-C adapter to measure energy in watt-hours drawn from the wall every minute, then interpolated the times to reach 50%, 80%, and 100% charge. Charge milestones were based on input energy, not what the battery reports, which “reflects energy delivered to the charger rather than energy stored in the cells.” For phones, reviewer Adam Doud used a Mecheer power meter in line with the outlet to watch live power draw for an iPhone 17 Pro Max, Samsung Galaxy S26 Ultra, and OnePlus 15. Ambient temperature, battery starting level, phone usage during charging, and cable quality all influence curves, so each phone was tested with its own cable and plug, then repeated with an Anker Prime GaN charger and Anker bio cable.
iPhone, Samsung, and OnePlus: how fast did they really charge?
On paper, the iPhone 17 Pro Max supports 40W wired charging, the Samsung Galaxy S26 Ultra is rated for 60W, and the OnePlus 15 advertises a headline-grabbing 120W with its 7,300mAh silicon carbon battery. In testing, the story was more nuanced. The iPhone briefly exceeded its 40W rating in the first five minutes before dropping down, while the S26 Ultra peaked at 61W and went from dead to full in under an hour. OnePlus was the biggest surprise: its own charger never approached the claimed figure and instead spent the entire session between 20% and 40% of that number, topping out at about 46W. That confirms a pattern already seen in power bank tests, where the fastest unit to 50% is not always the fastest to 100%. The headline wattage rarely describes the true experience from empty to full.
Do third-party chargers help or hurt fast charging?
Phone makers promote their own chargers, but third-party options can change the phone charging speed story. In Adam Doud’s fast charging test, an Anker Prime GaN charger paired with an Anker bio cable outperformed the original chargers for both the OnePlus 15 and the Samsung Galaxy S26 Ultra. That means a high-quality third-party charger can sometimes unlock better real-world charging performance than the plug bundled in the box, or the branded adapter sold separately. Apple’s 40W Dynamic Power adapter costs USD 39 (approx. RM180), while Samsung’s 45W travel adapter with magnetic wireless puck costs USD 71.25 (approx. RM330), which makes alternatives appealing for many buyers. Still, compatibility matters: phones and chargers must negotiate power safely, and poor cables or no-name plugs can limit speed or add risk, even when the phone itself supports high wattage.
How to read fast-charging claims before you buy
Fast-charging numbers on spec sheets are starting points, not guarantees. A phone rated at 60W might only spend minutes at that peak, and a 120W claim can mask far lower sustained power. Power bank testing showed the Cuktech 15 Air reaching 50% in around 26 minutes and 100% in 54 minutes on a 70W adapter, while another unit raced to 50% in about 13 minutes but took over three hours to finish. Those curves matter more than one bold number. For iPhone Samsung OnePlus charging, check independent graphs, not only marketing slides. Look for tests that state the charger, cable, ambient conditions, and phone state, and pay attention to times for 0–50%, 0–80%, and 0–100%. The most reliable way to choose is to treat wattage as a ceiling and focus on measured minutes, not big fonts on the box.
