what would happen with the current and voltage, if i put two different batterys parralel?

IF you're gonna play with electronic circuits, you need to invest some time in learning

basic circuit theory. The first thing to learn is Ohm's Law.

http://en.wikipedia.org/wiki/Ohm%27s_lawAs indicated, if you tie 2 nodes together, the current between the nodes is related

to the voltage difference between the nodes and the resistance from one to the other.

In your case, V = 6V - 0.5V and R = 0 ohms. Now calculate the current using

I = V / R.