Where can I get some old beat up lead acid batteries?

Hi folks, I am trying to source some old 12v lead acid batteries for development work on my EV.
I won't be using them to actually move a car, I'll just be using them on my test rig to experiment on my motor and controller in my workshop, so I don't care if they are old and have only a fraction of the capacity they had when new. I'm hoping to get them for free as they are basically scrap.

I tried putting an ad on craigslist but haven't got any responses at all. Where else can I try for these? I am looking for at least 12 batteries as my system is 144 volts.

Thanks!