Defender Run out of Electricity

Hi All,
Thought their might be loads of you that will know the answer to this straight of the top of your heads.

I think my Defender 90 (200 TDI) has a faulty Alternator, but I don't want to replace the entire Alternator if its just the brushes. Couple of nights ago. I was out over the fields. The lights got dimmer and dimmer until I couldn't see where i was going. stopped and the battery was completly flat. No RED Battery warning light. I jump started the Landy and put a volt meter across the battery terminals when the engine was running. the reading read 11 volts.

Anyone got any ideas

Cheers
J

look at this.

Check the battery warning lamp is not blown as this would cause the alternator to stop charging. The voltage to the exciter coil comes via the lamp. Broken lamp = no charge.

Thanks Guys, I've checked the Battery Warning light, works when ignition is switched on. All works OK it would seem.

alternator dead. Jus cos the light aint on dnt mean its charging. The alty can be comletely ****ed and the light still goes out like it should.