All-Electric 40-Foot Bus Using Lithium Batteries

This page updated April 12, 2007.

Heavy-Duty Transit Bus Using Modular Lithium Batteries

ISE Corporation

All-Electric 40-Foot Bus Using Lithium Batteries

Technology and Innovation
ISE’s innovative technology is all-electric propulsion using lithium batteries and its application to large (up to 40-foot) transit buses. Lithium batteries offer energy densities on the order of 160 watt-hours/kg, two to three times the energy density of nickel-based battery chemistries and four to six times that of lead-acid batteries. A three to five metric ton pack of lithium batteries could store 450-750 kWhr of electrical energy, which would support an operating range of 180-300 miles between charges. Lithium batteries are also expected to last longer than lead-acid and nickel-based batteries. If lithium batteries can be manufactured at projected costs – $500/kWhr within the next two to three years – a large market for electric buses could develop.

Development of a lithium battery pack that enables ISE to address this market is the key technological innovation of this ICAT proposal. Battery packs will typically be recharged overnight, using a high-power charger. As part of the proposed project, ISE will explore the possibility of employing “opportunity charging” on some routes, a process enabling batteries to be recharged during brief stops while the bus is in service. This would reduce the amount of batteries required to achieve a given operating range.
Emission Benefit
The proposed battery-electric technology will completely eliminate the tailpipe (and evaporative) emissions from mobile sources of critical interest such as transit buses, refuse trucks, and port vehicles, providing across-the-board reductions in vehicle emissions, including NOx, hydrocarbons, CO, CO2, and particulate matter. Based on data from the ARB’s most recent Emissions Inventory, estimated emissions of oxides of nitrogen (NOx) from heavy urban transit buses in California (diesel and natural gas) totaled 53.91 tons / day in 2004. This is nearly 20,000 tons / year of NOx that could be eliminated if all heavy urban transit buses in California adopted the ISE all-electric technology. Other aggregate emissions reductions would include 29,000 tons / year reduction in carbon monoxide (CO) and 336 tons / year reduction in particulate matter (PM). The proposed technology will also give vehicle fleet operators a practical option for meeting the California zero-emission mandates currently scheduled to take effect later this decade.
Project Description
The principal tasks of the proposed project will be to:


Design a prototype lithium battery pack.


Develop the software and controls required to assure battery health and safety.


Perform extensive bench testing of a prototype battery pack to validate its performance and safety before installing it into a bus.


Develop an all-electric variant of ISE’s existing ThunderVolt® hybrid-electric drive system, designed to operate solely on battery power and integrate this system, including the lithium battery packs, into a 40-foot transit bus.


Perform initial testing of the transit bus for proof-of-concept validation of the proposed technology


Demonstrate the optimized vehicle in actual revenue service with the Los Angeles County Metropolitan Transportation Authority (LACMTA), and


Manage the project, collect data, and provide reports throughout the program, including submittal of formal final reports to the ARB and other funding partners at the conclusion of the effort.

Funding Source

Funding Amount


$    290,000



Sunline Transit Agency

$   750,000

ICAT Funded Projects