Are individual batteries in the batter module isolated from each other

[PaulOpie]

Will a bad battery in a battery pack effect the other batteries in the pack, or are they individually isolated from each other. 

I have found that one replacement batteries in dropping its charge when connect, I am worried that the bad battery may effect the others, while I wait for a new battery replacement 

[Hectormp]

No, they are not isolated, the new battery will be discharged by the old batteries until they level up.