Car Battery

[Racer X]

elmo3, you obviously have very limited automotive theory background. Numerous alternator designs will operate if disconnected from the battery once the vehicle is running. What usually happens is you send a voltage spike at the moment that the battery cable is pulled, that fries an alternator's diodes. However, this doesn't always happen. I have on numerous ocassions done this with cars equiped with Delco 10 SI and 12 SI series alternators. Blusubaru's link says that it may damage the alternator, but nowhere does it say, for example, that the vehicle will shut off.

As for the voltage spike taking out diodes, in marine applications that use a battery switch, they even make something called a ZAP Stop, which is another diode essentially, that is mounted externally on your alternator. So if someone turns of the battery switch between the engine and tha battery bank, it won't fry the alternator, and the boat stays running.

And as for an alternator actually functioning without a battery to provide power for the field, there are numerous alternators that have a self exciting field. They are also know in the racing community as one wire alternators. You even see race cars with insulated posts on the back. This is for starting jumper cables, as many race cars have no on-board battery. They do have alternators though.

I am ASE certified, and I managed an auto parts store. I have seen and done a few things that you haven't done, and haven't even heard of.