Ok dc to dc converters can allow us to drop a battery voltage saaaay like a 7.2 v rechargeable down to the 6volt the servos and ezb need. Motors can handle a little overvolt sometimes. This is useful for dropping voltage for lights and LEDs too so your not wasting lots of power through tons of resistors. In my case I have a 12v motherboard and everything else runs lower voltage so the motherboard PSU goes straight to 12v and everything else is dropped to 6v as seen in the picture. Dc to dc converters range from 2 to 10th dollars on ebay. I opted for the nicer one with built in led display to show both input and output voltage which.is great for setups and trouble shooting without using a meter on every connection. Dc to dc converters are up to 96 percent efficiency meaning 4 percent is lost through heat.