It depends on where the wire is being connected on the alternator. It could be the alternator or it could be a damaged wire or connector. It's something that you will need to track down.
It is the wire that supplies the initial field current to the alternator from the battey. Once the alternator is rotating the field current will be provided by the diodes from the current produced by the alternator. excitor wire is usually wired through the charging indicator light.
Diodes and rectifier
No, the alternator is the charging device which runs off a belted pulley attached to the motor. The alternator charges the battery which is the source of the current required to get the engine turning over and in turn starting the engine.
The brushes on an alternator carry current.
An alternator produces AC current but it is converted to DC by the rectifier inside the alternator.
Engine Dies, but Runs for a while After Jump StartingIf you're sure the alternator is working properly, I suspect that you have a loose, or disconnected, connection of the conductor [wire] that is supposed to carry the alternator charging current to the battery, OR a battery that has become defective.
You need to check your battery and alternator, to start with. If you're lucky it'll be something simple like those two. Sometimes you can get local auto parts stores to check them it for free. Typically that means that the alternator isn't charging. Many auto parts retailers will test the charging system at no cost. Their hope is that you'll buy the replacement parts from them. An automobile will run for a while after the alternator stops charging, but when an alternator is not replacing the electrical current the battery will eventually discharge and without recharging the battery SOMEHOW, with either a functioning alternator or an outside charger, the engine will eventually fail to start.
The devices that develop electric power are a generator (for direct current), or an alternator (alternating current). In a car, an alternator is used, with a rectifier, because of size and weight considerations.
The Alternator is a component that acts like an electrical generator, charging a battery and powering necessary electrical systems. They are usually used in place of generators because they are lighter in weight, simpler to operate, and produce alternating current.
An alternator cannot "short" out for years or even minutes. The definition of a short is a wire or circuit touching ground to cause a fuse to blow. The circuit is too "short" for the current to flow through the proper load and back to the battery. The voltage regulator in a alternator can act up from time to time and cause improper charging from the alternator. Or a component of the alternator can go bad and cause a charging system problem intermittently. Your question needs to be explained better to give a better answer.
formals to calculate exciation voltage of alternator
Disconnect the cable from the alternator and see if that stops the draw. If it does, the alternator may be defective. Otherwise there may be something else drawing current.