As waste fleet managers assess their future truck choices, full electric and hybrid options should be on their list. Full electric vehicles have the greatest potential positive impact on emissions reduction, making them a more natural choice if you operate trucks in certain states.
By Andrew Schliebe
Transportation experts are predicting that as many as one third of all commercial trucks and buses will have alternative drivetrains by 2030. Many of these are expected to be fully electric. Data from research firm Markets and Markets confirms this, suggesting that the total market for commercial electric vehicles will grow at a compounded rate of more than 33 percent between now and 2027. With this push to vehicle electrification, vehicle designers will need to rethink how to power accessories.
Today’s vehicles with internal combustion engines rely on belt-driven accessories for power steering assistance, air conditioning and battery charging. With electric drivetrains, fans and alternators are eliminated, as are belt-driven accessories. Instead, air conditioning compressors and power steering pumps will need to be driven by small electric motors.
Five Key Qualities
The challenge with electrically-driven accessories in battery-powered electric vehicles is their range-robbing potential. If the motors used to drive the accessories are incorrectly spec’d, they could draw significant amperage, pulling down battery levels more quickly than desired and reducing the vehicle’s effective range. Ideally, the motors used to drive EV accessories should have five key qualities:
1. High output with low power draw—High efficiency is important to keeping the electrical draw to a minimum. The best measure for this is the ratio of electrical input power to motor output torque. Percentage efficiency is calculated by taking the Work out/Work in. Work in = Voltage*Current. Work out = Torque*pi*RPM/30. You should be targeting motors with efficiencies of 40 percent or greater.
2. Long life—Motors should be designed for several million cycles before failure. Commercial vehicles put on a lot of miles and will have high accessory usage. Fleet owners cannot afford frequent replacements.
3. Designed for harsh environments—Vehicles experience weather extremes and need motors that can handle heat, moisture, dust and cold conditions. Do not pick a motor that is not designed for these conditions. Look for motors with high ingress protection (IP) codes, such as IP67 or IP68, which indicate high protection from solids and liquids.
4. Programmability—By equipping motors with encoders, you can run them even more efficiently and adjust output/speed to changing conditions. Look for motors already packaged with encoders so you can save time involved in integrating with control systems.
5. Easy to replace—Sticking with simple, proven brushed motor designs is wise because of the many years of refinement in vehicle applications such as wiper motors. These motors are quickly and easily replaced at low cost.
Electric Vehicle Advantages
For the waste and recycling industry, the biggest expected growth for vehicle electrification is in residential waste pickup and removal. Not only can electric vehicles help to reduce emissions in urban areas, other advantages of electric-powered trash trucks are:
• Reduced noise: Eliminating diesel engines and traditional drivetrains significantly reduces the disturbance created by waste trucks in residential areas, helping improve relations between the waste company and the residential customers.
• Improved operating efficiency: With its high-frequency stop/start operations, residential pickup can be fuel-inefficient with diesel power and hard on braking systems. Electrically-driven powertrains use regenerative braking, which is more efficient and allows smoother ramp up and ramp down between each stop.
• Lower maintenance: Aside from the significant reduction in brake maintenance, electric vehicles also eliminate maintenance required for hydraulic systems typically used for pickup arms.
Evaluating Options
As waste fleet managers assess their future truck choices, full electric and hybrid options should be on their list. Full electric vehicles have the greatest potential positive impact on emissions reduction, making them a more natural choice if you operate trucks in certain states such as California with stricter emissions regulations and more aggressive timelines for eliminating combustion engines altogether.
The quietness and cleanliness of full-electric vehicles also offer more public relations value if its important for your fleet to improve your public image. And they may qualify for more subsidies from local electric utilities or from carbon credit programs.
However, hybrid systems (a small combustion engine generating power for an electric drive system) will likely be the most popular interim choice because it allows for a more managed transition from diesel-powered equipment to full electric. It will take considerable time and investment to change maintenance systems and parts supply chains for the new electric drivetrains.
Ultimately, fleet managers will need to weigh up the cost of disruption to existing maintenance infrastructure and knowledge systems before making a decision to electrify their fleet. | WA
Andrew Schliebe is Senior Engineer for AM Equipment, headquartered in Jefferson, OR. He has extensive experience in electric motor design and application engineering. Andrew can be reached at (541) 327-1546, e-mail [email protected] or visit www.amequipment.com.