New iPhone 6 and 6 Plus are equipped with more capacious batteries which provides them with additional time of battery life. However experts from iLounge have stated that their charging time too can be considerably reduced.
New iPhone are delivered with standard chargers which were not modified since release time of iPhone 5s, with current strength of 1 A and capacity of 5 Watt. You guess that with the same capacity of chargers and significant increase of the size of new iPhone batteries, their charging time should be substantially longer.
Experts from iLounge have carried out special measures using both standard chargers and chargers of iPad. A special device Kill-A-Watt and the system information from OS X were used for these measures.
The result of the tests was that the battery controller in new iPhone has much in common with the one installed in iPad. So irrespective of the used chargers iPhone 5s consumed no more than 5 Watt while being charged; new smartphones can use up to 12 Watt, which allows charging them much faster. Preliminary measures have shown that iPhone 6 Plus with its powerful battery of 2815 mA*h is charged within only two hours when using the charger from iPad.