At some point in time we believed that it is dangerous to make calls when the battery power of a phone is running low thinking that the low battery makes the phone to emit more radiations.Fortunately,at a point not too far from then,we discovered they were all baseless rumors.
To understand the basic facts about this topic,I think it's best we start by answering some questions concerning the topic in question.Questions like:

• What brings about radiation in phones?
• What does the radiation emitted have to do with the batteries in the phone?
• In what ways does that affect our health?
  Being cautious of time,let's get straight to the point.

What brings about radiation ?

Phones depend on signals from cell towers to send or receive data ( including sending/receiving text messages,making/receiving phone calls,and at the same time surfing the web ).In the process of receiving signal from those cell towers,cell phones emit a lot of radiations.
In areas with low network signals,cell phones emit much more radiations to send/receive more powerful signals so as to reach the nearest cell tower more efficiently.

What does the "radiation emissions " have to do with the battery?

Of course,like every other activities of the phone,this process requires energy.
In contrast to the former popular opinion that phones emit more radiations upon low battery,phones emit more radiations when they're in low network areas.
NOTE:The only proven relationship between radiations and battery is that the emission of radiations drain batteries NOT that low powered phones emit more radiation.

In what way does the radiations affect our health?

Since phones emit those radiations from antennas,the tissues closest to that antenna could end up absorbing the radiations.
But even at that,you don't have to be scared for these two reasons .The first is that the radio-frequency energy emitted from phones doesn't affect the DNA in a way to cause cancer. The second is that phones are better constructed this days in a way that will reduce the rate and frequency of emission.
You just have to be cautious when making calls that you don't make calls in low network areas because phones emit a lot of radiations then.Let me hang my pen over here.
Hope the article'll be helpful.Have a nice day.