98 Astra Mk3-ignition light came on while driving but got home and next day battery flat.On recharging car started but light still on and glowing brighter on acceleration.Voltmeter across battery terminals showing fluctuating voltage with all lights etc on-as low as 12 volts.1.6 petrol.is it probably alternator needing replaced?
you should be getting around 14 volts across battery when vehicle running. almost certian alternator is at fault here. you need to check wires to alternator from battery first though before changing alternator.
howtomendit.com for free repair help, information and advice.
