Copper Sulfate Pentahydrate experiment, help please?
Frankly you're going about this all wrong. First you want to exploit the difference in solubility of the salt in hot water versus cold water. 

Copper sulfate's solubility is 32 g/100ml water at 20 C, and 114 g/100ml water at 100 C. 

2-3 drops of sulfuric acid is all that is needed. You're just trying to prevent the formation of $\ce{Cu(OH)2}$ or $\ce{CuCO3}$.


  I'm not sure about battery acid. I assume that you're using new battery acid, not actually from an old battery. So the sulfuric acid will be a little less concentrated. Use 5-6 drops instead of 2 or 3. 


After you make a saturated solution of the copper sulfate (aim for 100g /100ml water) in hot water, let it cool slowly and don't stir at all. Stirring will promote nucleation of many small crystals. 

To get a really large crystal you'd make a saturated solution at room temperature, filter it, and add one of these seed crystals. You'd then let the water evaporate over weeks very slowly.