Battery draining in subway/poor signal?

[jamesino]

Is it normal for a phone's battery to drain and the phone to become hot when you are in an area with very poor reception? For example, I noticed that in the NYC subways, my phone battery just plummets and gets extremely hot and likewise in underground libraries with no signals. Is the phone constantly searching for a signal or something?

Can I alleviate this problem simply by turning on airplane mode?

 

[zkSharks]

Is it normal for a phone's battery to drain and the phone to become hot when you are in an area with very poor reception? For example, I noticed that in the NYC subways, my phone battery just plummets and gets extremely hot and likewise in underground libraries with no signals. Is the phone constantly searching for a signal or something?

Can I alleviate this problem simply by turning on airplane mode?

When your phone has very low reception strength, it channels increasing amounts of power to the antenna to try and maintain an adequate signal. Your battery usage will be significantly higher in areas with poor reception, but your phone shouldn't get hot. Warm, sure, and I wouldn't worry about it, but if it's getting hot to the touch that's unusual by my experience.

Airplane mode would solve the issue, yes. Also, if you have very poor 4G reception but better 3G, toggling 4G off will alleviate the battery issues related to that signal.