Haithar once I got two car batteries and connected them in series and than I connected straight to my old parallel plate cell 20 cm x 10 cm plates 0,1 or 0,2mm apart and I got h2 and ozone from water, I don't know the proportion it was it just smelled like ozone, in the water there was only sodium hydroxide. I used that kind of paper insulation for transformers to don't let the borders of the plate to touch the other to very close to each other.
I repeat the gas coming out smelled like ozone.
Regards