Need for suggestions on voltage regulation.

I'm making a model of the mars Curiosity rover. I'm using lots of servo's (6 modified ones for driving, 4 for turning, and a few more of various sizes for the arm and camera movement).

I'm planning on using a typical 2S2P LiPo battery (four cells, 2 of which are in series and two of which are in parallel), which should output 7.4V (I chose 7.4V because it's close to the voltage I need).

The 7.4V should be fine for the arduino (I'm going to use a Mega because of the large number of servo's).

The large servo's I'm planning on using (the 6 modified ones for driving and 4 for turning) should run at 6V and ~400mA each. 7.4V is too much for them.

Some of the other tiny servo's for the arm will go to as low as 4V.

I have no idea how voltage is regulated. With my understanding, a battery provides a constant voltage and as much current as is needed (with limits, of course).

What would be the best way for me to step down the voltage to 6V (at least 5A) and other voltages at much lower currents?

It might be as simple as using a resistor, I really don't know.

Would something like this work with electronic step-down transformers? http://imgur.com/6hFeZ6H

Use a switching regulator, www.pololu.com has a bunch of them to choose from. That'll be the most efficient use of your batteries.

Thanks for the tip. This is exactly what I was looking for. Do I use them like this: http://imgur.com/6hFeZ6H ? Sorry for the beginner questions, just wanne make sure :).

olafwillocx: Thanks for the tip. This is exactly what I was looking for. Do I use them like this: http://imgur.com/6hFeZ6H ? Sorry for the beginner questions, just wanne make sure :).

The switching regulators are 3-terminal devices. Your diagram appears to show current sources, which are 2-terminal devices. The 3 terminals are: Input, Output and Ground. They don't work without ground connected.

Most of the Pololu DC-DC converters also have a "shutdown" pin. Connect that to the input voltage so that it stays on whenever there is input power.

Some LM2596 DC-DC buck converters - they are cheap and several amp.