If you hold the wire in place on the battery with your finger, it will get hot and burn you. with a good battery it only take about 5 seconds for the wire to get this hot.
I use a 1/4" diameter and 3/16" high solid Neodimium magnet. The exact size is not impotant. The thicker magnet makes it easier to touch wtih the wire. My favorite magnet source is www.supermagnetman.net The magnets are inexpensive and the service is great.