The problem with running from the battery is that it is a long run, is not fused, and there is no switch meaning it is on when you plug it in, and off only when you unplug it. Rather than take a chance that the long wire gets chaffed and shorts out going all the way to the battery, take the time to find a "hot" wire under the cover of the handle bar and connect the wire to that. It will be fused, won't be as likely to short out and when the key is off so will the power to the shield.