A battery power system includes a number of battery modules. The walking cane includes a trigger that can be actuated to mechanically operate the jaw-grip from an open to a closed position. The method also automatically establishes the conference event using a moderator code responsive to determining that the invitee is the moderator of the conference event. Each LED of the first and second plurality of LEDs is mounted proximate a heat sink and a drive circuit is provided for the LEDs, with the drive circuit being located proximate and electrically connected to the screw base. A surface region of the third nitride semiconductor layer between the ohmic electrode and the Schottky electrode contains an element heterogeneous with the constituent element of the third nitride semiconductor layer at a higher concentration than a region of the third nitride semiconductor layer of the second nitride semiconductor layer side. This can prevent malfunctioning due to displacement of the electrode plate group when an impact or vibration is applied.