Voltage is largely irrelevant. The less the better.
28 volts? What kind of battery does THAT? Did you even read the article? The whole point is that we can do it ourselves.
Printed copy · Anthology Volume 3, page 798Printed copy from The Tender For Law Anthology, Volume 3, page 798 (printed 13 June 2014). Added by this site; not part of the Facebook export.