alternator test

ive got time and effort, cant be doing with taking it to people cos half the time they just dont want to knmow cos it isnt brand new and its a 3.9 in a defender and it has got mud on it

you should be seeing something like 14.6 volts at the battery terminals with the engine at reasonably high revs. If not then it's an unhappy alternator. Is the ignition warning light comming on when you turn the key (before starting the engine) if the bulb has blown it will stop the alternator charging the battery as it's connected in series. Sounds daft but this is the case on some systems and I'm pretty sure Land Rovers are one of them. Check for cracked wires and dirty terminals and of course the belt tension. Have to agree with the others about taking it to a specialist though. Cost me £30 to get mine sorted. Look for an auto electrician in yellow pages. Small workshops are usually pretty helpful.