Question

Are the chemical reactions that take place when a battery is connected endothermic or exothermic? be specific as you explain your answer.

Answer 1

The question is too broad. Depends of the battery and depends where do you connect it to.

define first a battery reaction and where it is connected to define if the reaction is endo or exothermic.

If a battery reaction is exothermic when it is connected to a circuit may be endothermic when it is charged (reverse reaction). 

some batteries at low temperature tends to work less, that suggest, they may need absorb some energy from the surroundings.