Ultracapacitors Give Power Lift to Automated Guided Vehicles

by | May 17, 2012

The commercial and consumer vehicle markets have made significant inroads in cleaning their technology and improving the performance and lifespan of their energy storage systems. One way to achieve this is by using ultracapacitors in combination with batteries to reduce emissions and store more power in smaller packages. The ultracap-battery combination improves the power density of the hybrid supply and reduces system size, thereby decreasing vehicle weight and improving fuel efficiency. All those benefits are now in reach for manufacturers and users of automated guided vehicles (AGVs), which include tow vehicles, unit load carriers, carts and forklifts. The next generation of AGVs will reap the rewards of supercapacitors, multiplying the longevity of their energy storage systems by as much as four times beyond the lifespan of battery-operated vehicles.

The need for a better energy option

Users adopt AGVs to move goods around distribution centers, production lines and other industrial settings without the need for onboard operators or drivers. AGV owners choose automated carts and carriers to reduce the risk of injuries and save money they would otherwise spend on personnel to operate these vehicles. However, the inefficiency of the energy storage options previously available for AGVs cuts into those potential savings. That’s because AGVs, which have traditionally relied on battery-based systems, require bursts of high power for lifting or dumping. They also need continuous energy for travel between stations. These requirements drain battery life, forcing users to switch out or recharge their energy sources every six hours. Since the typical work shift is eight hours, AGV owners are not only losing resources by having to replace or recharge batteries, they’re losing time shift employees could spend more productively.

Enter the ultracapacitor. Unlike batteries, ultracaps hold their charge for eight hours of continual work – a full shift – while also extending the overall lifespan of the energy storage system to 10 years. For example, a facility might have inductive charging installed under its floor. When the AGV stops to load or unload material, it gets a rapid charge to the ultracapacitor, and the vehicle moves on to its next stop, where it recharges again. Each charge provides enough power to get to the next charging location, and the vehicle owner captures the highest possible productivity from the vehicle. The AGV can operate 24 hours a day, seven days a week with no battery changes or respites from work.

Ultracaps also take advantage of regenerative braking, a system proven in hybrid passenger vehicles, to capture energy that would otherwise be lost. The ultracapacitor can then release the stored energy and use it to power the AGV when necessary. Supercaps maximize performance and the run time of AGVs, providing a dependable energy storage system with a long lifespan.

A prime application for ultracaps

Forklift manufacturers have tested out several technologies over the years in attempts to increase the efficiency of their vehicles. Their success was limited, and they have traditionally settled for batteries as the energy storage system of choice. However, batteries have proven to be less than satisfactory. They are energy dense but not power dense, and they have temperature and lifespan limitations that affect productivity. Increasingly, forklift manufacturers are adopting ultracapacitors in tandem with batteries. Ultracaps are power dense, but not energy dense, and they allow for a lower charge rate, enabling the application to operate at a lower temperature. The result of the ultracap-battery combination: longer lifespan and better performance.

Ultracaps also offer other benefits to forklift manufacturers and AGV owners. In an emergency situation, ultracaps provide enough energy for peak shaving, which lowers the power to a safe and manageable level. In full-crane operations, users need only four megawatts of ultracap banks. Ultracaps also increase the life of the batteries with which they partner; a 3,000 pound lead acid battery partnered with an ultracap can last up to four hours, when alone it would last only one hour. And finally, ultracaps have endured and successfully completed crash tests, meaning they are rugged enough for the nature of the work AGVs do.

Ultracapacitors are particularly useful in dynamic systems where applications perform several accelerations that last just a few seconds. These rapid movements, typical in AGVs, set the stage for energy recapture, which ultracapacitors excel at doing. The high-power and high-energy applications in the AGV market can benefit significantly from a hybridized solution of ultracapacitors and batteries, while seeing a payback on the ultracapacitor investment in just 18 months.

The market for ultracaps is expected to grow rapidly among AGV manufacturers in the next year or two, and it’s clear to see why. Manufacturers of these vehicles will benefit from the cost savings, performance enhancements and longevity made possible by ultracapacitors, and AGV users will gain from those advances.

Jeff Colton is vice president of sales, North America at Ioxus.  He is responsible for managing and growing the company’s North American sales operations in multiple alternative energy sectors. Previously, Jeff held executive roles at companies including General Electric Corporation, Sanyo Electric Corporation and Saft Battery Corporation. Jeff can be contacted at jcolton@ioxus.com or (858) 663-1609.  


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