Quote Originally Posted by kinyo View Post
this used to be ok for old school cars without sensitive electronic components

modern cars, those with ECU's, have sensitive electronic components, the ECU itself and sensors, aircon controls, alarm system, stereo, etc. can be damaged with this procedure ...

[SIZE=4]removing the battery terminal/s and letting the alternator supply power alone can produce transient voltages up to 80 volts on the system ... and if you happen to have a defective/shorted regulator (inside the alternator) or a shorted diode, you're asking for a disaster![/SIZE]

[SIZE=6]you were warned! don't ever let anybody do this procedure to your modern cars![/SIZE]

consider yourself very lucky if your car survived this dangerous test!
a failing alternator that surge hiigher voltage will damage any electrical system regardless wether the battery positive is connected or not.
the positive line that connects the battery and alternator is there to recharge the battery via alternator.nothing more.
when the car is running..the battery doesnt do anything anymore in regards to the electrical system of the car unless the alternator isnt giving enough amphere/voltage to power up the rest of the electrical system.
the clicking sound you hear when starting the engine comes from the starter.the alternator doesnt have anything to do when starting the engine.its mainly the battery cranking power and the starter.