Sorry, I explain myself really bad. I mean that, with a battery in it and in passive mode, I thought that the preamp wasn't using any battery power, and I was wrong. If I remove the battery, I can use it in passive mode without any problem. However, I prefer the active mode. But my concern is that it only lasts for about 8 months... Other players in my area with active basses (non Yamaha. They use Musicmans, Sadowsky, Sire...) claim that they don't change the battery in at least one year and a half or even two. That's why I think that my preamp might have something wrong