About “fast” wireless charging
Apple notes on the product pages for both the Mophie and the Belkin charger that fast wireless charging will be enabled via a software update due later this year. As of now, actual charging speeds will be close to the same speeds garnered from the 5W Power Adapter included with the iPhone 8.
Although the latest Qi specification (version 1.2) supports 15W wireless fast charging, the iPhone 8 and iPhone X will only support half of that. This appears to be either a software or hardware limitation, or a combination of both.
Once the “fast charging” update is applied, charging wattage will increase by 50% up to 7.5W, which should provide a subtle, yet noticeable increase in charging speed. We will be sure to test the chargers again once the update goes live, but technically all of them, sans the Anker Wireless Charging Pad, supply enough output to support 7.5W fast charging. The issue, however, may have to do with secure encryption. We’ve heard through unofficial channels that only supported partners (in this case Belkin and Mophie) will support the faster 7.5W charging.