However, if you're in a pinch and need some extra battery fast, then using a larger amp charger won't destroy your iPhone. The iPhone does not need 2.1 amps forced inside it, but it will handle it. People claim the iPhone is designed to handle more than 1 amp of power, such as the iPad's 2.1 amp brick. It’s a little slower than the 35W adapter, as you might expect. You get to a half charge in just under an hour, about 10 minutes longer than the 35W model. A full charge takes about 140 minutes How to Test Your Wireless & AC Chargers [Android 5.0+]Full Tutorial: http://gadgethacks.com/how-to/are-your-chargers-faulty-slow-heres-test-them-android-0159 An iPhone should accept 2.1A from that. There are a lot of power adapters that provide exactly 2.1A because a lot of portable devices max out on USB-A at that current. It's just a regulated voltage supply though. The power adapter could max out at 1000A and it would be perfectly safe to use with an iPhone. Reply. .

how many amps to charge iphone