Assembe the PositiveWire to the plug prong Published October 9, 2010 at 800 × 489 in Extending battery life for battery powered devices ← Previous Next → Assembe the PositiveWire to the plug prong Because we’re going to use the back end of the plug as the negative terminal, a small hole is made into the plastic plug body about 1/8th dia. that is used to route both positive and negative wires out of the plug body.