Will Rapid Charging Damage Your iPhone 6 Or 6 Plus?

Based on recent marketing campaigns, if there is one area where new Android phones have iPhone 6 and iPhone 6 Plus beat, it’s rapid charging.

With the Galaxy S5, Samsung’s “fast charging” technology became “ultra fast charging.” Motorola’s Droid Turbo promises an 8 hour charge in just 15 minutes. With the release of HTC’s Rapid Charger 2.0, 2014 HTC devices like the One M8, the One E8 and Desire Eye will charge 40 percent faster.

Meanwhile, the new iPhones promised increased battery life, but no quick charging. However, as bloggers quickly discovered, the iPhone 6 and iPhone 6 can also play the quick-charging game. Just plug them into the 2.1A/12W charger from an iPad or the high-power USB port of a newer model Mac.

This raises the question, why doesn’t Apple advertise this feature? And, more importantly will it hurt your phone if you try this? I’d like to be able to answer the first question, but the first rule of Apple PR on this topic is you don’t talk about Apple PR. It is possible, however, to deduce from the web page Apple created “Charge the battery in your iPad,” that Apple is aware of this capability and endorses it.  The Apple store lists every iPhone from the original “iPhone” to the iPhone 6 plus as being compatible with the iPad charger.

Ivan Cowie, chief engineer at MaxVision and author of an EE Times series, “All About Batteries,” notes that the iPhones have actually been charging at a lower speed than they are designed to charge at. Simply increasing the current from .5 amps (USB charging cable) or 1 amp (the bundled iPhone charger) to 2.1 amps (the iPad charger) boosts the charging speed.

What effect will this have on your device? More amperage equals more heat, and more heat equals more wear and tear on the battery. For this reason, it’s common for people to conclude that using the iPad charger is a bad idea. Apple’s silence on the issue isn’t particularly encouraging either. But in this case, knowing just a bit more about how batteries work may ease your mind.

Isidor Buchmann, founder and CEO of Cadex Electronics and author of “Batteries in a Portable World,” explains a key measurement that determines how much charge a phone can safely receive is the C-rate, or the rate at which a battery charges or discharges. To determine a C-rate, simply take the ratio between the charging rate and the capacity of the battery as measured in mAh or milliampere-hours. For an iPhone 6 that is being charged with the iPad charger, the C-rate is 2100mA/1810mAh or 1.16C. For an iPhone 6 Plus, the C-rate is 2100mA/2915mAh or .72C.

Most portable batteries are rated at 1C.  This puts the C-rate that we calculated for the iPhone 6 and 6 Plus in the safety zone.  ”A battery manufacturer would recommend a rate below 1C,” Buchmann said. But a rate that is just barely above 1C is nothing to be concerned about, he added.

Another thing to keep in mind is how rapid charging typically works. This is how George Paparrizos, a director of product management who works on Qualcomm’s Quick Charge 2 technology explained it to me:  A bit of code on your device, often located in a chip known as the Power Management IC, communicates with the charger you are using and requests that it send power at a higher voltage. The Power Management IC, also known as the PMIC, receives this voltage and converts it into a voltage and current that is suitable for a particular battery. In theory, this step would protect the battery of an iOS device because Apple would still determine the voltage and current provided to its batteries, regardless of your choice of charger.

In fact, both iPhone 6 and iPhone 6 Plus feature a PMIC made by Qualcomm. So while Apple isn’t talking about power management and Qualcomm isn’t talking about Apple, it seems safe to conclude that rapid-charging iOS-style will not damage your phone or significantly degrade its battery.