Though I would share a problem I have recently had - basically battery going flat, do the usual alternator check of checking battery volatage before and after starting the engine - 12.5v before, 13.6v with engine running.
To cut a long story short, I connected a long set of leads to my multimeter to the battery and monitored it whilst driving. Bottom line is after about 10-20miles (variable) the voltage suddenly plummets - the alternator stops charging bascially.
So... if you have such a problem, before blaming the battery (which is what I was going to do after finding the car with a flat battery a couple of times) check you don't have this problem!
For the record, the car has covered 260k miles, and I changed the brushes on the alternator after it stopped charging a little more conventionally about 30-40k miles ago.
Tref.
To cut a long story short, I connected a long set of leads to my multimeter to the battery and monitored it whilst driving. Bottom line is after about 10-20miles (variable) the voltage suddenly plummets - the alternator stops charging bascially.
So... if you have such a problem, before blaming the battery (which is what I was going to do after finding the car with a flat battery a couple of times) check you don't have this problem!
For the record, the car has covered 260k miles, and I changed the brushes on the alternator after it stopped charging a little more conventionally about 30-40k miles ago.
Tref.