My "phone" feature is my top battery consumer 90% of the time. It generally fills out the whole bar. And there's a reason for that.
When I'm at work, my phone is almost always sitting on my wireless charging stand. I'll send emails from it, text message, browse Grin (Imgur), tweetium, baconit, etc. All this time, it's on the charging stand. The battery app registers the use of those apps as going off of power, not battery.
When I get a phone call, I take the phone off of the stand and hold it in my hand. Thus, the battery app registers the phone as a battery consumer, not a power user. It makes a lot of sense.
I'm not sure if that's the case with your phone. But if so, it's not battery drainage. Just a nuance of using a device while on and off a charger.