I have a bad habit of buying the most expensive 9Vs I can find. I was oddly excited about Josh Scott's last April Fools joke video about vintage 9Vs (my favourite April Fools of all time).
I had a 1984 Boss battery that was in the box with an OC-2 I bought and it was still registering high 8’s on the multimeter, although no load. I don’t want to use it and waste the vintage volts. Heh.