Lithium Ion Batteries Boost Power and Lower Operating Costs

Lithium Ion Batteries Boost Power and Lower Operating Costs

By Joe Marshall, Product Engineer for the Hybrid System at Terex Utilities, Terex Jon Promersberger, New Product Development, Terex Stanley Mlyniec, Engineering Manager at EnerSys Advanced Systems, Mike Kulesky, Director of Marketing for Next Generation Technologies and New Applications for EnerSys Reserve Power

Increasingly strict regulations have presented several challenges to makers and operators of today’s heavy-duty aerial device vehicles.  Hybrid charging system technology and lithium ion batteries are helping the platform/boom/bucket truck industry meet its unique needs, while helping to comply with today’s regulations on weight restrictions, fuel efficiency, emissions and idling.

The Evolution of the Bucket Truck

Originally known as a “cherry picker,” the bucket truck has evolved in the last 50 years from a simple bucket on a boom to a sophisticated, multi-purpose vehicle. Now used by industries from utilities to construction, today’s vocational trucks serve many functions and feature a wide variety of booms, buckets and aerial work platforms (AWPs). Other changes include upgrades in comfort, steering and handling.

Some of the biggest improvements in today’s aerial work platform (AWP) trucks, however, have been in flexibility and environmentally friendly performance:

Flexibility:  Today’s utility trucks are available with booms, buckets, diggers, drills or AWPs. These can be positioned in various locations on the truck and precision-controlled to enable workers on the ground and on the platform to adjust height, angle and movement for maximum efficiency on the job. 

Environmentally Friendly Performance:  Since the dawn of the current green movement in the 1980s, green engineering has helped to protect the environment while reducing operating costs. Owner/operators are looking for ways to cut fuel consumption and emissions. In response, utility truck users are demanding greater fuel efficiency while seeking ways to maximize their fuel investment.

Regulations Impacting Aerial Device Trucks

The trend toward greater fuel efficiency is being propelled by increasingly strict regulations governing manufacturers and operators of today’s heavy duty lift vehicles, including the following:

Gross Vehicle Weight Ratings (GVWR):  The U.S. Environmental Protection Agency (EPA) and Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) classify trucks in eight gross-vehicle-weight (GVW) classes. GVW is defined as empty vehicle weight plus cargo weight. There are transportation and cost implications to exceeding established GVWR. As a result, today’s bucket trucks are being built with narrower profiles, smaller footprints and greater efficiency.

Fuel Economy:  In November 2011, the EPA and the NHTSA announced a first-ever program to reduce greenhouse gas (GHG) emissions and improve fuel efficiency of buses and heavy-duty trucks, including vocational work trucks, which are the second largest contributor to oil consumption and GHG emissions in the transportation sector. The agencies estimate that the new standards will reduce carbon dioxide (CO2) emissions by about 270 million metric tons and save 530 million barrels of oil over the life of vehicles built for the 2014 to 2018 model years. Overall, the HD National Program will cost the industry about $8 billion, while providing vehicle owners $50 billion in fuel savings over the lifetimes of the vehicles. The majority of vehicles will see a payback period of less than one year.^{see footnote #1}

Truck Idling Laws:  Conventional utility trucks utilize the chassis engine to power the boom/bucket/AWP by way of a power take off and hydraulic pump.  Typically these systems require the engine to run at idle, while the operator is working with the boom in the air. The chassis engine provides about 80 horsepower while idling, yet the boom only requires about 20% of that power, making it an inefficient use of the diesel-powered engine.

According to a study done by the Argonne National Laboratory, the total fuel use by idling trucks is estimated to be over 2 billion gallons per year. The type of idling done by vocational trucks during the workday — referred to as Power Take Off use — often is not measured by studies such as this, as useful work is being done while the engine is idling.^{see footnote #2}

However, a study by Advanced Energy, a nonprofit organization that helps companies achieve energy goals through consulting, testing and training services, showed that vocational trucks idle for approximately three hours per day. Assuming that each truck operates 250 days per year, this results in 750 hours of idle time per year per truck.^{see footnote #3}

Meanwhile, Terex Corporation, based on surveys of its customers, estimates that the average utility truck consumes 4.8 gallons of fuel per day during this idle time. This means that, in just one year, utility trucks use more than 1,000 gallons of fuel per truck – while sitting still. Terex estimates that this wasted fuel translates to more than 10 metric tons of CO2 per truck per year.^{see footnote #4}

It’s no surprise then that many states and municipalities have enacted strict no idling laws to reduce air and noise pollution. These specify the duration and conditions under which trucks may idle and the fines for exceeding these restrictions.

Hybrid Power Systems Cut Noise, Costs and Emissions

Truck manufacturers have developed auxiliary stored energy systems that allow for boom/bucket operation while the engine is off.  For example, the Terex® HyPower™ system uses additional batteries on the chassis to provide hydraulic power in order to power the aerial device. The auxiliary batteries also provide power for in-cab environments and for charging battery-operated hand tools, like drills, impact wrenches, crimpers, etc. The most efficient way to charge the auxiliary system is to plug it into a standard 110-volt household outlet overnight. However, if the batteries require charging during the workday, a control system starts the engine to enable a quick charge. The run time is typically limited to five minutes but is programmable to any predetermined amount of time.

The hybrid power system offers many user benefits:

• Less engine idle time:  Approximately 750 hours less engine idle time annually.^{see footnote #3}
•  Reduced fuel usage/less time spent refueling: Terex estimates that each HyPower™ system equipped utility truck will have the equivalent positive impact of nine hybrid passenger cars– saving 1,205 gallons of fuel per year (compared to similar conventional vehicles).
•  Reduced engine wear: The vehicles may be spared up to three hours a day engine running time.
•  Elimination of jobsite noise/improved communication with worker in the bucket:  A standard truck continuously produces 75dB of noise 10 feet away from the truck. As a normal conversation is just 60 dB, standard trucks make communication difficult.3 A hybrid truck periodically emits 73 db of noise when the pump is running, but it only runs for a minute or two at a time. The rest of the time, the system is silent, except for the sound of the electronics and the hydraulic oil flowing through valves.
•  Reduced emissions: The primary GHGs emitted by today’s diesel utility truck segment are CO2, methane and nitrous oxide. Heavy-duty trucks account for nearly six percent of all U.S. GHG emissions and 20 percent of transportation GHG emissions.^{see footnote #5} These GHGs may contribute to global warming, smog and acid rain. Resultant global warming also can cause an increase in “climate sensitive” diseases, such as malaria and dengue.^{see footnote #6}
•  Cost efficient to retrofit: An auxiliary power system can be added to an existing utility truck, at a fraction of the cost of a new hybrid vehicle. In fact, the Terex® HyPower™ system has been designed to outlast their first vehicle so they can even be reused on new chassis.

 Lithium Ion Batteries Deliver Higher Energy Density

Installation of an auxiliary stored power system adds weight to the chassis. Given today’s GVWR restrictions, the user may need to give up weight capacity typically used for tools and supplies. The advancement of lithium ion (Li-ion) battery technology, however, has allowed for overall weight reduction while improving the performance of the battery system. A Li-ion system offers up to three times the energy density of standard AGM lead acid batteries and provides much greater cycle life.  This results in a system that weighs approximately 300 pounds less and lasts at least twice as long. Additionally, multiple batteries can be strung together to provide longer run time while adding little weight. Additionally, multiple batteries can be strung together to provide longer run time while adding little weight.

Li-ion batteries are more flexible and perform well even in partial state of charge applications — such as when a job runs overtime or requires overnight travel. For example, using quick charging methods, a Li-ion battery will provide far more cycles than a lead acid battery and will require fewer periodic boost charges than the lead acid battery.

Summary

Local and federal regulations are calling for higher fuel economy from utility trucks. At the same time, local ordinances also restrict idling times. This hampers the utilization of traditional power take-offs to power utility booms. New advanced Li-ion battery technologies have the potential to alleviate these restrictions by providing temporary power for short periods of time.

For more information on Terex® equipment, visit terex.com. For more information on the Terex® HyPower™ hybrid system, visit terexhypower.com.  For more information on EnerSys Reserve Systems, visit Enersys. com.

Footnotes:

1- EPA Regulatory Announcement, Office of Transportation and Air Quality, EPA-420-F-11-031, August 2011.

2 - Paper 06-2567 -“Estimation of Fuel Use by Idling Commercial Trucks” by Linda Gaines, Anant Vyas, John L. Anderson, Center for Transportation Research, Argonne National Laboratory

3 - Progress Energy Bucket Truck Monitoring,” June 09, Advanced Energy.

4 - http://www.terexhypower.com/environmentally-concerned/

5 - EPA Regulatory Announcement, Office of Transportation and Air Quality, EPA-420-F-11-031, August 2011

6 - World Health Organization, http://www.who.int/mediacentre/factsheets/fs266/en/

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About the Authors:

Joe Marshall is a Product Engineer for the hybrid system at Terex
Utilities. Joe received his Bachelor of Science degree in Mechanical
Engineering from South Dakota School of Mines and Technology. He previously worked as an Installation Engineer at Terex Utilities interfacing the boom to the chassis.

Jon Promersberger is currently in New Product Development at Terex
Utilities. He graduated from North Dakota State University in 1974 and has
held various engineering positions at FMC, Crane and Excavator Div.; Condux
International, and FMC, Naval Systems Dev. Promersberger received a patent
for a hybrid system in 2011.

Stanley Mlyniec is an Engineering Manager at EnerSys Advanced Systems. He and his team are involved with the research, design and development of advanced lithium-ion battery systems. He has a Bachelor of Science degree in Electrical Engineering and a Bachelor of Arts in German from the University of Rhode Island and a Master¹s in Engineering Management from Drexel University.

Michael Kulesky is currently the Director of Marketing for Next
Generation Technologies and New Applications at EnerSys. Michael received
his Bachelor of Science from Pennsylvania State University majoring in
Operations Management and Business Logistics and holds an MBA in Global
Management. He started his career managing the manufacturing floor at a
Philadelphia plastics manufacturer. He then accepted an offer at American
Home Products where he held several Operations Management positions.
Continuing in his career he joined Lucent Technologies where he completed
his tenure as a Senior Manager of Power and Batteries Supply Chain Network.