four in a row or four in parallel...like a deck of cards?
four in parallel.
If it is like this you are ok.
View attachment 458664
You have overload protection, but not reverse polarity protection. So just dont put a battery in backwards.
Resistance in this situation would be VERY low and not a concern.
W00h00! I done did 'er good! This is for my LIPO, mikep, so as long as I don't connect the battery terminals in the dark (knowing me, there is that possibility), I should be gtg.