I was in Target and saw a kids toy that was a bunch of rare-earth magnets in plastic rods with oversized ball bearings, Kinects or something. It was 12 bucks for what amounted to 100 or so rare-earth magnets. So I bought it.

Got home and began clipping the magnets out and doing some experimenting.

5 seconds with a 40 watt soldering iron on a button magnet will DESTROY it's magnetic field. It'll go from hard to pry off with fingers to won't hold a piece of paper to a pair of pliers.

I made a bunch of jumpers with the magnets for charging various LiIon/Lipoly batteries I have around the house. I ended up sticking the magnets to a honking big monkey wrench to heat sink it as best possible and dripping a dollop of solder on the magnet, then after pre-tinning the wire I'd melt as little of the dollop as possible to fix the wire. Then, after letting that cool down I'd hit the whole thing again till the whole solder blob spead out. I'd say I kept 90% of the original magnetic strength that way. Magnets do not like heat at all. All that chatter we hear about keeping motor temps down is some solid advice.

Small admission here. I love the smell of flux and solder. I'll solder something that really only needs a good crimp JUST to get that smell.