Secondhand car batteries?

[Bretty]

Hi all,
I'm trying to get hold of a cheap/secondhand car battery. Any ideas where I could get one? Is that something an auto salvage company would sell and if so what should I expect to pay?


Basically, I want to charge some Li-Po batteries for a drone, but want to do it  outside and off the mains, so I can leave them charging unattended  without the fear of them burning my house down.


Any ideas?


thanks,


Brett