Tin ( put solder on ) both .... you might find that Flux or Bakers fluid will help you tin the battery tags.....
A high wattage soldering iron will also help.

Id tin the wire first ...... then as soon as the battery tag is tinned.. and still hot.. solder on the wire.

http://www.fernox.com/?cccpage=bakers_no_3_soldering_fluid&sub=9http://www.fernox.com/?cccpage=baker...ng_fluid&sub=9

(Message edited by woody on January 07, 2007)