Good stuff! 
For future reference it is good practice to remove any battery that is present in an old (or even newer) Mac you pick up and either leave it out or replace it with a brand new one. Fresh stock from Saft, a reputable brand used as OEM parts in Macs for years, are cheaply available from eBay in the 1/2AA size used in all Mac's other than the 128k/512k/Plus series, right through until theswitch to button cells in the late dual-core models of the G5.
For future reference it is good practice to remove any battery that is present in an old (or even newer) Mac you pick up and either leave it out or replace it with a brand new one. Fresh stock from Saft, a reputable brand used as OEM parts in Macs for years, are cheaply available from eBay in the 1/2AA size used in all Mac's other than the 128k/512k/Plus series, right through until theswitch to button cells in the late dual-core models of the G5.