This happens to all my buds,its normal; but its commum to happen to the right side; that IS the master; anyways, just found this on internet, hope this helps.
""""""When the faster draining one hits about half way, put it in the case and let the other pair to your device before taking it out again, this will change the “master” earbud and then drain the other side faster instead, which should even out and give you more overall battery life out of one charge. If you don’t want to use the case, a simple power off\on cycle works too, as long as you allow the “slave” to pair as “master”."""""
