Comparing batteries to generators as power sources for use with mobile robotics

• Published in: Journal of power sources 2012-08, Vol.212, p.130-138
• Main Authors: Logan, Drew G., Pentzer, Jesse, Brennan, Sean N., Reichard, Karl
• Format: Article
• Language: English
• Subjects: Allometry; Applied sciences; Batteries; Battery; Direct energy conversion and energy accumulation; Electric batteries; Electric motors; Electric power generation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Generator; Generators; Power sources; Robot; Robots; Vehicles
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.03.041

This paper considers the scaling principles associated with the power and energy density of batteries and generators as applied to mobile robots and similarly-sized vehicles. We seek to identify, based on present technology, the size range at which a generator inclusive of a direct current electric motor, gearbox, and internal combustion engine can be effectively used to replace modern batteries. Models were derived to scale each component of the generator as a function of power, mass, efficiency, and speed. For a given power, energy, or mass requirement, these models illustrate that generators based on conventional technology are ill-suited for smaller robots. The results indicate that there is an intermediate robot size above which a hybrid generator/battery architecture is desirable. Using these scaling principles with modest extensions of existing battery technologies, it is also possible to infer the near-future performance of robot power technology and thus illustrate whether the generator-versus-battery tradeoff will shift toward or away from a hybrid robot topology for smaller vehicle systems. ► We compare batteries and generators as power sources for ground robots. ► Allometric scaling principles are used to size generator components. ► Generator components are optimally sized for a required power output. ► Batteries always have a higher power-to-mass ratio than generators. ► Above 0.9 kg, generators have a higher energy-to-mass ratio than batteries.