The battery sparks a lot when i try to connect the cables.The poles began to fry and i need to separate them.I place the cables over the correct battery poles.If i leave them in place i can damage the battery?I have a volvo 740 1987 without turbo.Thanks for the attention.

 

Sounds like something might be shorted out, the ignition is off right?

Connect Pos cable to battery ,
put a meter between Neg and car frame, see what you get.