FYI: The following is just what I do. It’s not meant to be official advice. Use your own discretion if you’re buying the $299 ASUS ZenFone 2 and/or contacting them with your own questions/concerns
ASUS says not to be concerned if you feel the special charger is too warm. I did a 40-minute test and the hot temperature of the charger made me contact ASUS with a sense of urgency. I told them I wouldn’t charge the ZenFone2 overnight, unattended. They responded saying it’s intentional.
Although the battery charger does get hot (and ASUS is aware of this), if the product senses you’ve got a low battery, while the charger stays in the wall and your battery fills, the charger “knows” to draw less power, just not at first, if your battery’s low. So it’s the speed charging feature responsible for making the charger hot in the beginning.
Then after awhile you can actually touch the charger and it’ll feel normal. Again, the longer it stays in the wall, the more it knows to return to normal.
So, to see if what ASUS was saying was right, I did a 91-minute test and ASUS’s response proved accurate because after that test, I forgot about the test for a good hour after it was over – The good news is, the charger didn’t even feel warm. But do a 40-minute test like I did, on a low battery and you’ll probably notice the charger is hot to the touch.
So for me, all’s good in the hood. I think the phone will be a hit with people who travel. At $299 unlocked, dual SIM card slots, etc, well, where can you get that? For most, the ZenFone 2 will be a solid investment. I haven’t tried the camera or cam yet, but I will.
Important: The speed charger is only given to you for free if you buy the $299 model of the ZenFone 2, not the lower-priced one.