Battery Draw Back

Hi guys,
Has anybody on the forum fitted an R&G tail tidy to their bike, and had the battery drain down whilst the bike is not in use? not over a long period of time but sometimes in the space of 7 days. And yes the battery has been replaced even though the original battery was tested and passed as being OK.
Replaced the R&G tail light with the original and the battery was fine, it only seems to be when the R&G tail light is fitted