Alternator and Battery

Z

ZUM

New Member
Can anyone provide a simple explanation of the relationship of the alternator to the battery? I'm not 100% on this. Here is my understanding: The battery is simply a storage container for excess electrons. The alternator is an electron pump that pumps electrons through the accessories of the airplane and into the battery. The two purposes of the battery are (1) to provide enough electrons for the alternator to pump through accessories and (2) to produce the electromagnetic field within the alternator. If (1) there were enough electons from ground (ie on the conductive parts of the plane) and (2) the alternator field was produced by some other means, a battery would not be necessary (once the airplane has already been started). Is this line of thinking correct?
Thanks
 
[ QUOTE ]
Can anyone provide a simple explanation of the relationship of the alternator to the battery? I'm not 100% on this. Here is my understanding: The battery is simply a storage container for excess electrons.

[/ QUOTE ] Correct.[ QUOTE ]
The alternator is an electron pump that pumps electrons through the accessories of the airplane and into the battery.

[/ QUOTE ] Also correct. It generates the power consumed by the electrical accessories and the power stored in the battery.[ QUOTE ]
The two purposes of the battery are (1) to provide enough electrons for the alternator to pump through accessories and (2) to produce the electromagnetic field within the alternator.

[/ QUOTE ] Not exactly. You don't really need a source of electrons to "pump", the electrons are already present in the wires and components. The alternator/generator provides the motive force to move them around. As for #2, you're right, the alternator needs a source of electrical power for its internal electromagnets.[ QUOTE ]
If (1) there were enough electons from ground (ie on the conductive parts of the plane) and (2) the alternator field was produced by some other means, a battery would not be necessary (once the airplane has already been started). Is this line of thinking correct?
Thanks

[/ QUOTE ] In some aircraft you can turn off the battery master in flight and everything will still run, but it is not recommended. What happens here is the alternator provides power to excite itself, but since the battery also acts as a shock absorber for the electrical system, the avionics can be damaged.
 
Thanks for the reply. So essentially then, other than for providing the electromotive force for the initial start up, the battery's primary purpose is to act as a buffer for the electrical system?
 
Other than proving electric power for start, the battery's primary purpose is to provide electic power for the electical equipment when the engine is not running (on the ground) or as a backup in the event of an alternator failure. Acting as a shock absorber is a nice by-product but I wouldn't say its a primary purpose, but yes it is one of the purposes of the battery.
 
[ QUOTE ]
Thanks for the reply. So essentially then, other than for providing the electromotive force for the initial start up, the battery's primary purpose is to act as a buffer for the electrical system?

[/ QUOTE ]

Sorry, should have made that more clear. flyguy is right, its promary purpose is to power everything when the alternator is not producing electricity. One of the things that needs electricity at that time is the alternator field, to start making more electricity.
 
Think of the standard "water wheel" model often used in physics. The alternator is pump that moves the water, the electrons are the water, and the battery is the resevior. If the pump fails, then the resevoir uses gravity to keep the water going, but only until it's out of water itself.

Clear as mud?
 
That all makes sense. I guess my source of initial confusion was whether the alternator was doing the job of DIRECTLY moving the electrons through all of the components as opposed to the battery directly doing this, with the alternator simply replenishing the voltage into the battery. I think i understand now. The alternator does directly do the work when everything is functioning properly with the engine running.
 
You must log in or register to reply here.
Back
Top