iPod Nano Battery Problems

I recently purchased an iPod Nano in September 2015 and have not been able to get more than 4 to 4.5 of playtime out of a fully charged battery. I have reset the software on iTunes, let the battery run completely down and recharged, and changed the on screen lighting with no improvements. I also turn the unit off when I'm not using it. My last attempt was to look at the headphones. My primary use is when I'm cycling and the apple ear buds will not stay in my ears so I purchased a set of Phillips Action Fit Sports Earhook Headphones (SHQ3200/28, Orange and Grey). One thing I have noticed is to get the same volume output out of these headphones as I do with the apple ear buds I have to turn the volume control on the music and volume limit all the way to high vs mid-way with the ear buds. Can the Phillips Headphones be the reason I'm not getting more hours of playtime on the Nano?