Historical clue formulations

• Band with the 1991 #1 hit "Unbelievable" — 2016-10-30
• Voltaic cell meas. — 2009-07-30
• Energy expressed in volts: Abbr. — 2009-01-03
• Generator output: Abbr. — 2007-01-19
• Band with the 1991 #1 hit "Unbelievable" — 2005-11-27
• Techno-funk band with the 1991 #1 hit "Unbelievable" — 2004-05-23
• It's expressed in volts: Abbr. — 1998-12-19
• Voltmeter meas. — 1997-08-08
• "Unbelievable" rock band — 1995-05-28