Ceruleanplains.com - Amateur Robotics Project Journal

Thermal Control System and Power Subsystem

Two subsystems that are typically separated in major design efforts are the TCS and Power subsystems. TCS is the purpose of managing heat rejection or insulation to a vehicle to maintain it's nominal mission operation parameters - too cold and materials may become too brittle, too hot and materials may become too pliable and melt. Power sub-system involves the scoping of a designed power system in order to achieve a desirable endurance via the vehicle's hardware need for energy in the form of stored (batteries) or other form of energy.

Battery Pack: From Andy Lindsay's Robotics with the Boe-bot

Resistor Color Code

Energy storage in Batteries

Reference source: http://www.allaboutbatteries.com/Energy-tables.html

I merely converted tables into GIFs for my uses here.

The table below shows the battery volume for cell sizes AAA, AA, C, and D. The volume does not change with the type of battery, but the weight does, as shown here.

Energy storage in AAA batteries

Energy storage in AA batteries

Energy storage in C batteries

Energy storage in D batteries

Lithium-Thionyl Chloride -- Special Mention

Although non-rechargeable,Lithium-Thionyl Chloride has the highest energy storage per kilogram of any battery type. Lithium-Thionyl Chloride cells do not supply high discharge currents, typically 1/10 the current of other cell types. However they last for 20 years, and withstand temperature extremes of -55 to +150 degrees C. For more information on Lithium-Thionyl Chloride batteries, contact Tadiran Battery Co.

Finally, if you would like a D-size battery that can supply 20 amperes of current for a short time (5 seconds), that will last for 10 years, check out the Ultracapacitor at Maxwell Technologies Inc. It is not really a battery at all, it is a 350 farad capacitor rated 2.5 volts. Yes, we said farads, not microfarads. As such it can store 277 Joules at 2.5 volts. This is not a great amount of energy storage, hence the limited discharge time. However, it can deliver more peak current than a lead-acid battery of the same size, and it recharges easily more than 500,000 times. The cost compares favorably with other D-size rechargeable batteries, but the cost per Watt-hour is not too good, $195.

Conceptual Power Considerations

References: http://www.engineering.sdsu.edu/~hev/energy.html

Source of Figure: http://www.nrel.gov/ *

Plot of energy versus power for various energy storage devices.*

Capacitors

http://www.arar93.dsl.pipex.com/mds975/Content/components01.html

Links to Projects:

Home
Up

About the Author:

An astronautics engineer, the author is interested in studying artificial intelligence and more specifically the intelligent agents created to accomplish specific tasks. The goal of his projects are to build a robotics test bed for experimentation and discussion amongst peers.

Contact Author