White powder on the battery tray,sometimes can hear the battery sizzling, have added water. I went to the local auto parts store and they put a meter on it.Checked out as good( 15-16 volts). Then I revved the engine and the needle intermittently started fluctuating into the overcharging zone.Auto parts guy said it could be alternator or regulator. I thought alternator only put out what it had coming in. Is it the alternator or regulator in your opinion? Thanks, SCott!