Battery Voltage DX6i

[sham]

Quick question, a bit of a beginner question I'm afraid.

I don't have rechargeable batteries for my radio, so I just put fresh AAs in every now and again. I was just wondering if the effectiveness and range of the radio drops with the voltage or if it stays the same until the battery alarm goes off at 4.5v?
I got nervous and changed them at 5.5v, but just wondering if anyone else replaces them early or if you wait for the low battery warning - or close to it.

[renard80]

I have always waited for the alarm before changing the Tx batteries, without problem.

As always, though, I am open for the more technically minded to advise that I am being foolish!