Ask A Scientist General Science Archive

Question:  How can I recharge a dead magnet?  Thanks! :-}
 mleyba

Answer:
Some magnets are not rechargeable, and some are only marginally so.
Generally, however, it is necessary to subject the material to a
very high intensity electro-magnetic field for a short period of
time repeatedly.  There are machines that are built specifically for
that purpose.  Many Permanent Magnet DC Motor repair facilities have
these devices.  They are used to "recharge" the field of these motors.
Many of these motors used to use AlNiCo magnets which would recharge
very well using charges of, say, 1,000,000 watt-seconds for approx.
10 ms.  This charge would have to be repeated several times, depending
upon the gap between the field and the magnet material, the amount of
the material, and the amount of original magnatism lost.  Ceramic
magnets are not as nearly successful.  Sumariam Cobalt magnets as
well as NdFeB (Neo-Iron) magnets recharge the best.
-- dipper