I have a battery pack surge protector for every machine. I was at a quilt retreat with my Bernina 440 and ruined the mother board, because of low power flow. My dealer told me to use one with a battery unit to keep continuous flow to the machine. I have told my guild members this story, but it happened to another quilter a few years ago. They are only 40-50 dollars at Best Buy, and worth every penny. Low power flow is just as dangerous to your machine as too much power.