Expert: John F. Iannuzzi - 5/25/2007

Question
I'm wanting to build a round electromagnet that is 3" in total diameter (coil included).  I want to make the most powerful magnet possible to run off the power of a car battery.  What gauge wire should I use to get the maximum number of turns without overheating the wire?  What size
core (width and length) should I use and what material?  What will the approximate hold (LBS) be?  Any other design specs/tips you can provide would be helpful.  Thanks!!

-Brady


Answer
Brady,
although this seems like a simple problem on the outset, it could get complicated.  I can only suggest a couple of things.  There are some safety issues as well.  The current that can be provided by a car battery could be a much a 100amps.  You must somehow limit the amount of current.  The magnetic field is dependent on the current, number of turns of wire and the construction geometry of the magnet core itself.  There is a lot of experimentation involved.  There could also be a lot of HEAT generated.  
John