I need to power a bunch of RGB LED strips on my cosplay, however, the batteries seem to run out extremely fast no matter if there is 2 or 6 9vbatteries powering the LEDS. the LEDS are 12v, however since there are so many of them, they are quite dim with only 18v. I feel like there is something I am missing electronically, like, some sort of bottle neck so that adding more batteries will actually increase the duration, not just the brightness.