Alternator or battery?

[davidball]

I seems everything is happening at once. I took my se7en out to fill her up (painful) and thought I would take the scenic route home. I stopped to admire the view along the river and lo she would not start. I got the dreaded solenoid clunk. I have fitted a new starter but checked to see if it was too hot or jammed, but no. I put the lights on and tried the starter again and sure enough the lights dimmed to nothing. The battery is only 6 months old. I cannot understand how it could be flat after driving for 30 mins or more. Is there any way to check whether the alternator is putting out enough juice?

[DKL]

David,
Do these engines have a voltage regulator in the alternator? Other cars I have had have had these fail which gives similar syptoms to yours. But it means the alternator is ok.
Did you change the starter and solenoid or just one bit?

[davidball]

Hi DKL,

I do not know if there is a voltage regulator in the alternator. I will take it off in the morning and get its model number and check on the internet. The starter is an inertia type so the solenoid is a separate unit mounted on the bulkhead. I am charging the battery over night so if the car starts ok in the morning I have got to suspect the alternator.

[pikeyboy]

how aboout getting it started and putting a voltmeter across the battery, if the volt meter shows 14 volts'ish (say 13.8 - 14.2)while its running the alternator is working OK.

[davidball]

Thanks but I cannot start it at the moment. I think the whole issue is due to a bad earth connection (see other post regarding melted wire).

[davidball]

Thanks pikeyboy. I have fixed the starting problem (see Burning wire Horror story). The battery is showing 13.49 volts at rest and 14.9 volts when running so it looks like the alternator is ok. The whole problem seems to have been the lack of a heavy-duty earth strap from the battery neg to the chassis.