The City of Chicago has awarded San Francisco Bay Area startup Motiv Power Systems an up to $13.4-million contract for 20 Class 8 electric refuse trucks. The 52,000-lb trucks, powered by a 200 kWh battery pack, will have a range of up to 60 miles.
The Motiv electric Powertrain Control System (ePCS) uses off-the-shelf batteries and motors, which can be mixed and matched to fit the size of the electric truck application. Motiv says that its ePCS can handle electric trucks from medium-duty to Class 8 heavy-duty, weighing 15,000 lbs-52,000 lbs. Motiv suggests the ePCS design approach cuts operating costs by 50% over an eight-year period. With a medium-duty pilot shuttle, Motiv reduced operating cost from 80 cents per mile ($0.80/mi) to 10 cents per mile ($0.10/mi). (Earlier post.)
In total, the City of Chicago has 600 garbage trucks in operation. Recently at the 2012 High-Efficiency Truck Users Forum, Chicago said it evaluated the option of hybrid and compressed natural gas (CNG) refuse trucks before requesting bids for the 20 EV refuse trucks. The city ultimately found that its garbage routes did not enable hybrid or CNG vehicles to be financially viable, and turned to the all-electric option to meet its needs. The city confirmed this analysis by placing a hybrid garbage truck into service.
Motiv’s battery pack design typically consists of multiple battery modules. Each module has its own unique Battery Management System (BMS), and is typically in the range of 1 to 20KWh, depending on application. Motiv combines modules to build battery systems, with a system-level controller managing module interaction.
Motiv says that this design allows for the independent management of each module and for coordination of modules across the whole battery system. Since each module is decoupled, problems or failures in one module will not affect other modules.
Motiv’s battery system design is simulation-driven, with a focus on both charge and thermal management. Motiv uses standard ICs to measure voltages of every cell. Its proprietary software combines the present voltage measurement with past voltage measurements and coulomb-counting circuitry and battery cell models to arrive at an accurate measure of cell state of charge. Using cell state of charge, it then actively balances the cells to ensure weaker cells do not bring a module down.
Motiv custom-designs a heat exchanger based on cell, module and system simulation to reduce the thermal gradient across a module, and across the complete system.
Motiv has been validating its ePCS since March 2012 with an all-electric pilot bus. Funded by a grant from the California Energy Commission, the 20 passenger bus contains 5 battery packs (125 kWh) which can provide a range of more than 120 miles on a single charge.
The Motiv EV refuse trucks planned for Chicago will use the same ePCS system as the pilot bus, but include a larger motor, and 10 battery packs. The EV garbage trucks will also use an electric motor to drive the hydraulics system.
Scaling up from the medium-duty pilot bus to the Class 8 garbage truck is really just a matter of switching out components and re-packaging it onto the new chassis. We’ve designed the whole system to be compatible with any off-the-shelf motors and batteries, which are brought to a uniform operating standard by our software. If Chicago ever wants newer batteries, the old ones can be easily swapped out.—Jim Castelaz, CEO of Motiv
The Motiv ePCS is designed to be assembled by the existing diesel chassis infrastructure already established throughout the world. Motiv will work with its partner, Detroit Chassis, to install the ePCS on to a standard refuse chassis. Loadmaster will provide the truck bodies.