A TACKLIFE 500Wh portable power station (i.e. a battery) won't power up a Rumble 15W and I'm wondering why. Maybe the amp has some instantaneous surge load that the TACKLIFE can't provide, so it doesn't even try (no red light)? I haven't put an ammeter (clamp) around the cord yet, but if it is some sort of instantaneous surge demand...I'm not sure the ammeter will be able to detect the draw (prob. need a scope). Even still, I wasn't expecting any significant amp draw until I started playing at a volume north of zero. Does anyone know the specs/requirements of the Rumble 15W?