Hi Klaus,

"Checking voltage output is easy. Start the car, pull off the positive cable from the battery and check the voltage from that cable to a ground point. If the engine dies, both brushes are no longer making contact inside the alternator."


The procedure you've just outlined is NOT for fuel injected car. Lifting the positive cable off the battery (engine is running) while alternator still connected to car's positive cable could damage the ECU. The switching diodes in the working alternator produce voltage spikes that are suppressed by the battery. Unsuppressed spikes could damage the ECU and cause engine non-start.


It is okay to do this in a carburettor car which I have done many times. Start the dead car with a good battery then replace it with the previously half-depleted battery while engine is running (this when I have no jumper cables to use).


Regards,
Amarin.