Think that I have 2 pack of batteries. In the first pack I have 6 batteries and each battery is giving 1 Volt and 0.01 Amperes, and the second pack of batteries are 2 batteries and each one is giving 0.3 Volts and 1 Amperes.

So, we have:

 

First pack

6 Batteries (6(1 Volt, 0.01 Amps))

Second Pack

2 Batteries (2(0.3 Volts, 1 Amp))

 

Can I obtain 6.6 Volts and 2.06 Amperes, putting all the batteries togheter?

I asked the same question to one friend and he told me that I only can get 6.6 Volts at 0.01 or less amps, or obtain 2.06 amps but decreasing the voltage.

I have to say that all the batteries are the same kind of battery.

 

Making a serie of parallel connection? How many voltaje would decrease in the second case (when I want the 2.06 amps)?

The current limit for a battery is determined by its internal resistance, so in series you are limited to 0.01A. Trying to drive more can damage the battery. I don't think you could quite get 2.06A, because you can't put all of the batteries in parallel — some small amount of current will go through part of the circuit that ties the batteries together.