VS playing up after some help. alternator?

[lok]

hey guys just driving home then and a few lights on the dash came on(abs off, airbag), then the headunit turned off and wouldnt come back on. then all lights dimmed and high beams barely put out any light. then car totally died and i was on a long slope so put clutch in and rolled tried to roll start it a few times but nothing. my old man came down jump started it and had enough battery to get home but then turned it off and wouldnt start again. so im thinking the alternator is stuffed. im after some peoples thoughts on what they think problem is. cheers

[Not_An_Abba_Fan]

Check the thick yellow wire coming off the back of the alternator, if it looks burnt close to the alternator, then that is your problem, you will need to cut it back a bit and fit a new connector. It could be the alternator itself, or it could be the battery. How old is the battery?

[lok]

ok cheers i'll go check it out. dunno how old battery is cos only bought car a couple weeks ago but i've had it playing music and everything over the last few weeks for a fair while with engine off and its started back up fine and everything so battery has seemed fine. can a battery just shit itself really quickly? or does it usually gradually wear down? charged it up last night and did about 30mins drivin today and it started to lose power again and almost konked out on me drivin up my street

[Not_An_Abba_Fan]

Yes, a battery can fail enough where it won't hold charge. Sounds like the alternator though. Do you have a multimeter? With the car running put it across the battery and see what the alternator is putting out. Also check the back of the alternator, they should be within a couple of tenths of each other. Just over 14 volts.

[lok]

just having a look at it again. i was reconnceting battery and the negative terminal does not tighten around battery connection bit, it sits there very loosely and will not tighten any more. could this be the problem?

[Not_An_Abba_Fan]

Yes, it could be. Replace that first and see how you go.

[lok]

thanks for your help mate

[immortality]

start with some good clean and tight battery terminals.

then check to see that the voltage sensing wire is properly attached to the positive terminal (small wire that has it's own little plug). if that is ok then get a cheapy multimeter from dicksmith/jaycar ($15 when on special).

with the multimeter you should see 14volts at the battery with the engine running. if your not getting 14volts (or atleast 13.5volts) then there may be a issue with the charging circuit. test the voltage at the postive output of the alternator. if this reads 14volts then there is a issue with the main charge cable. if it reads less then you possibly have a alternator problem ( assuming that the voltage sensing wire is properly connected)

with the engine off the battery should show 12.4-12.7volts. have someone crank over the engine and the battery voltage shouldn't drop bellow 12 volts. readings lower then 12volts indicates the battery is stuffed (or atleast discharged)