[Elecraft] K2 - Internal battery life?

[Rick Wheeler]

My K2 No. 2005 (I think I built it late 2000 or so) is probably 6 or 7
years old. I have it set up with the remote 100 watt amp/tuner and the
K2 itself with the low power tuner and internal battery option. 

My question is how long can I expect this battery to last? My greatest
fear is someday opening up the K2 only to discover acid leaking out
from the battery onto the main PCB. Has there ever been an instance of
the internal battery leaking?

Rick
K4LX
No. 2005