Alternator or battery

[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.