My computer gives me a shock; Some details: Supply: 250 V/50 Hz. Neutral to Ground at plug-point: 4-5V. Power On (UPS), but no equipment drawing power: 9V (Computer-case to Earth). With everything powered ON: 20V (Case to Earth). Everything ON: 5V (Earth to Neutral at powerstrip - before the UPS).
My UPS batteries are very weak and give about 4-5 minutes backup on power-failure. Could this be causing the problem? How do i check to see if the battery is dead?