I've got a Battery Minder Plus charger maintainer conditioner that I've used to bring back to life some batteries I thought were junk. You have to leave it in the conditioner mode for at least a week, I let it work for 2 or 3 weeks. It won't bring back a battery with a bad cell or internal shorts but I had an 8 year old Bosch battery in the basement for 2 years and was testing at 150 CCA. After I got the Battery Minder I hooked it up for a week and tested it again. It was up near 300 CCA. After another week over 400 CCA. And by the end of the 3rd week it was at 535 CCA and almost at 13 volts.

I say leave it connected a good 2 weeks and see what it puts out then.