No they do not, but Stan used a Redi-line inverter for the early prototype of the dunebuggy. We have pictures of that.
The 8xa was not designed to run on a 12V source (in a car), but was designed for the patent office to demonstrate the electrical polarization process on Stan's plate cell. Stan's original box ran on 120V AC (standard US household voltage). It can, be used in a car if an inverter is used. I have seen this done numerous times successfully...