Amiga 500 memory expansion battery..yikes!!

[Exluddite]

I recently picked up an Amiga 500 with the 512 memory expansion in it. Great condition, still in the box, needless to say I was psyched when I got it.
When I opened Workbench, I'd get an error message about the battery, so I decided to take a look at the memory cartridge.
I'm glad I did. The battery (probably from sitting unused for so long) has white froth on one side. Luckily I noticed this early enough that it still works and doesn't seem to have done any damage beyond the battery itself.
Does anyone know if I can get a new battery for it?
Those with the same cartridge (and any system with a battery) check your battery now!!

 

[Kaptain Skitzo]

Yes, actually most parts stores(like Radio Shack) still carry them. Or you could order them online. I suggest you look at the pics that I posted a while back, and see how to make sure the new one doesn't damage the board.