Never liked the tiny 3.4 volt battery of the ego. Much preferred, when I was a newbie, a true 3.7 volt battery like the Kgo. That is until I listened to the Vets and tried a 5 volt battery and realized what I was missing. Now I just use a variable wattage model and vape between 4.7 - 5.0 volts and realized why it's called the "sweet spot".