The term trigger point was coined in 1942 by Dr. Janet Travell to describe a clinical finding with the following characteristics: Pain related to a discrete, irritable point in skeletal muscle or fascia, not caused by acute local trauma, inflammation, degeneration, neoplasm or infection.
A fresh alkaline zinc battery can have an open-circuit voltage of 1.6 volts, but an iron-disulfide battery with an open-circuit voltage below 1.7 volts is entirely discharged.
This could be a 9 volt battery or 6 volt dry cell for rejuvenation of small, low voltage battery packs, or a 12 volt car battery or charged up power tool battery for higher voltage power packs. If you need more than 12 volts, you can connect two 12 volt batteries in series as shown below to get 24 volts.