The original charger put out 13 volts A/C, but according to George Payne a 12 volt DC charger can be used. Here's the link to the post he made http://jb-ms.com/Discovery/Sept18-2006/1157416049.html.
Mr Bill should still have new 2.2 chips. You can contact him via email at email@example.com or firstname.lastname@example.org. He checks this forum most days, so he'll likely see your post and respond.