How do i do this to my baterry.

how do i calculate the correct polarity to determine the voltage in wich multiplies the amps connecting the plates and posts to discover the c,c,a reading on my 12 v deep cycle batterry in wich it allows me to transform it to a 24 v batterry with wiring it to have only one open circuit tester on the pos post..

p.s this is to ginko. im a mechanic and i know the answer, he always thought he was on top but now we will see if he can cover the answer for me.