Power supply

Introduction

We need a power source for robot, the cheapest and easiest-to-use source is Pb battery for UPS and electonic devices. The battery is unfortunately very hight weight, this is important disadvantage. Typical PB battery 12V/5Ah weights 2kg.

Advantages:
- low cost
- simple and cheap battery charger
- simple construction (we don't need many batteries installed in battery basket)
- high output current

Disadvantages:
- very high weight  

We need:

• Pb battery, in my construction 12V/5Ah
• XL6009 DC/DC converter for computers line (Raspberry and Arduino); output 5V/3-4A; spec
• DC3 5V0 DC/DC converter for power line (Servos, DC motors); output regulated 1,25-35V/2A
• Watt meter, optional for easy measurement power consumption
• some devices to connect, in my test connection Raspberry Pi with camera and Arduino

Battery 12V/5Ah dedicated to UPS.

Watt metter for easy measurement power consumption. This's an optional element.

XL6009 DC/DC converter for low power line.

DC3 5V0 DC/DC converter for hight power line.

Connections

We need two power line. Line of computers can not be affected by the heavily loaded servo or motors. Therefore, I used two DC/DC converters.

Before connecting the Raspberry to XL6009, set the correct voltage using voltometer and resistant load device. Raspberry will be damaged if you do not adjust the valid voltage.

 Connection diagram.

Real connections (without battery charger).

Power consumption

I measuremend power consumption devices:

• XL6009 DC/DC (converters have efficienty 75-98%)
• DC3 5V0 DC/DC (converters have efficienty 75-98%)
• not load RaspberryPi with ArchLinux
• RaspberryPi Camera
• WiFi dongle
• ArduinoMega

Average power consumption is 2,3 Watts, theoretical battery can work 28 hours. In real construction we will add other devices, 28 hours is "standby time".