It is impossible for a 6 cell lead acid battery to EVER get a voltage potential of zero volts. What part of that don't you understand!!!!!
I was under the impression that speedster 1919 wanted to somehow kill his battery to 0 and measure the internal resistance. You cannot measure resistance in an energized circuit ever!
Repeating the excercise with a discharged battery would be more informative. (But I don't have any easy way to discharge my battery at the moment.).
This is what he wrote down. It does not make sense because he states in parenthesis that he has no easy way to discharge the battery when as you stated its discharged when its 11.8 to 12 volts. I was under the impression that somehow he wanted to totally kill his battery if possible and measure its internal resistance.[:-]