One of the things we discovered is it actually takes a lot less current and energy to start engine than we originally thought. It's rare that anyone even uses 1

One of the things we discovered is it actually takes a lot less current and energy to start engine than we originally thought. It's rare that anyone even uses 1% of the capacity of a regular lead-acid while cranking. So we're confident 10AH is more than enough. The high capacity of most lead-acid is really just a side-effect of making a battery that can deliver high current over a reasonable lifetime.