Our robot eats too many batteries! We’ve already bought 2 packs and I think it is not the end!

Actually I’m not sure that it is normal. I do not think that that 2 motors (3^rd one haven’t been used yet) and small processor requires so many batteries. And also one of the motors does not work well. At the beginning we thought that it does not work at all, but later on we noticed that he worked in 40% of times. May be one of the contacts is faulty?