Guess it can happen with Tadiran batteries. Tested out an SE/30 that I got today. Wouldn't boot, showed what looked like a mixture of checkerboard and the normal startup screen on the monitor. After repeated attempts to get the machine to boot, I got out the T-15. Opened it up, found some capacitor leakage that was visible from under the motherboard. Pulled the board and found this:
As per usual, the battery holder wasn't attached to the board anymore. So, I'm thinking it'd be a good idea to replace these guys, no matter what brand they are, on a 10 year schedule. Maybe sooner.
I also tore into a IIcx that came with the SE/30 and a bunch of other machines. No explosion yet from the Tadiran battery, but it was getting a little stinky and corroded looking.
Mac: 512Ke, Plus 4/0, SE 4/40, SE/30 8/40, IIx 8/230, IIcx, IIci 20/250, Q660av, iMac G3/333 Tang, G4/1.2GHz DA 1.5G/40G/DVD-RW, G4 MDD 2G/80G/30G/DVD-RW, C2D 2.16 iMac 2G/250G
Apple II: ][, ][+, //e x2, //c
Other: iPhone 4, Dell D830