Hi. I was offering to trade my acoustic/electric Epiphone El Capitan for a fully electric bass and I got an offer for a Yamaha RBX-375. While the reviews seem great, one thing I've noticed is that it takes batteries for some reason. What would a fully electric bass need batteries for? I tried to find this online but couldn't find an answer. I know that for my acoustic/electric bass, it takes batteries for the pick-up but I can't see why it would on a regular electric bass. Could anyone give me insight to this? Thanks.