Hi Bruce, just to correct your opening post, to fit the Lightspeed Attenuator the plug has to be 2.1mm (not 2.5) and centre +positive. You have to ask the ebay sellers but most are 2.1mm and + centre but ask just to make sure.
http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&_nkw=12vdc+Li-Ion+rechargeable&LH_PrefLoc=2
Cheers George
http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&_nkw=12vdc+Li-Ion+rechargeable&LH_PrefLoc=2
Cheers George