battery light coming on when just after starting the engine

[westy 90]

after starting the engine on my 300tdi defender the battery light comes on very faint. Give it a little rev and it goes out. Any ideas ? i think it mite be the alternater. 

[Axetamer]

Usually its the alternator, if you've been offroading the brushes can stick a little, if its a lucas type you can take the plate off the back of the alternator in situ, 3 screws hold it on, you may have to thin the wall on a socket to get them out as they sit in small counterbores, 7mm I think

[ARMYBOB]

alternator

check out put it may work a bit but o/p will be down

i just changed a friends for this reason

its was 12.5-13 now up to 14v again

[Saffy]

maybe check the engine idle speed is correct first before fingering alternator ?

[crazymac]

Maybe even check the belt tension before you spend money??  :doh:

[Landroverstormer]

I had the same, then finally the tensioner gave up and the temp guage flew up!  Just caught it all in time though!

[Saffy]

Maybe even check the belt tension before you spend money??  :doh:

was gonna say that but with 300tdi if there is a tension problem with serpentine belt then alternator light is least of worries, lack of steering and overheating too.
Saying that... if the belt is in poor nick or contaminated... :-k