Mounting tab and cannister sealing joint disintegrated from battery acid.

New mounting tab fabricated, and mating joints sealed.

Mounted back in the car.
I know this is an old topic, but it has haunted me with my 2004 XK8 for many years. I changed the cannister close valve a few years ago and I thought I had it beat but after a few months it was back again.
Finally for my first project this winter I made myself a good smoke machine and got into it. I took the hose off at the solenoid that is behind the front fender and blew smoke into the evaporator line. I got a small amount of smoke out of the charcoal canister that is under the battery. It turns out that the vent hose from the battery comes out right beside the cannister mount and it would appear the cannister end cap and mounts have been eaten away, this happened on a friend's 2005 XKR a few years ago and we put a little glue on it and it fixed it, I don't know why I never made the connection to my car.
Anyway, I removed the cannister filed away a lot of the plastic that was messed up, fabricated a new mount bracket and sealed it up with JB weld. I tried the smoke test again and all is well.
The location of the battery vent hose would seem to be a design that was not well thought out. My latest battery does not have a vent, so I don't see any further problem.
The car is off the road for the Canadian winter so it will be a few months until I know it is fixed.