Alternator or battery

[NigelP]

Is this a one off problem , or has it developed to a point it will not start?

Completely sudden, starting perfect every day up until this morning.

 

[Strima]

An alternator is designed to replace that charge lost during starting and it can take a while for it to do this. If the battery is flat or has a low voltage the alternator will never charge it no matter how far you drive.

Modern cars have very specific power requirements and need a stable voltage to run correctly. Charge the battery or fit a new one. Most vehicles charge at around 14.5 volts.

 

[ruston]

Are you certain you did not leave anything on that would have flattened the battery to a level it would not crank?

 

[NigelP]

Are you certain you did not leave anything on that would have flattened the battery to a level it would not crank?

Completely, I locked the car and this deactivates anything left on but it definately did not have anything left on.

 

[NigelP]

An alternator is designed to replace that charge lost during starting and it can take a while for it to do this. If the battery is flat or has a low voltage the alternator will never charge it no matter how far you drive.

Modern cars have very specific power requirements and need a stable voltage to run correctly. Charge the battery or fit a new one. Most vehicles charge at around 14.5 volts.

So the alternator should be performing at a volt more then it is.

 

[ruston]

Take it do a well equipped garage that has the equipment required to test the battery properly , they will also test the alternator for you. They will know if the battery is defunct if they have the proper gear to test it with. The equipment is quite sophisticated now.
It is worth the extra to have it done properly.

 

[Strima]

So the alternator should be performing at a volt more then it is.

The battery could be pulling the alternator voltage down. An alternator needs voltage to operate correctly so a dead battery will not help.

 

[DPG]

As above, replace the battery and get the alternator checked to be on the safe side.

And don't buy a cheap brand battery. They are a waste of money.

 

[Mike Johnson]

Halfords do decent batteries, and give good guarantees with them, keep the invoice, but do get your alternator checked at a decent garage.