can anyone tell me the difference in wireing batteries

[Mr.lst]

I want to know the difference in how to wire lipo batteries for more run time. and to run 2 smaller batteries like 2 2s together to get 4 s for my revo. I currently have 2 4s batteries and I want to run them with my mamba max but the esc gets warm quickly. it has a 9l motor and 20 pinion gear and a 66 spur gear.it also has a e savage tranny if that helps. I have a xlt1 from fine design that I can use once I get a pinion gear from mike. my concern is that the mamba max heats up reather quickly as well.