by Jack Rosebro
By the end of February, Valence Technology, Inc. will ship an additional 600 custom modules of Valence’s Lithium-ion batteries to OEMtek for use in the conversion of Toyota Prius hybrid vehicles into Plug-In Hybrid Electric Vehicles (PHEVs). Valence previously supplied OEMtek with 300 modules for installation in vehicles which are now being shipped to customers.
Valence’s custom module for OEMtek’s BREEZ (Battery Range Extender EZ) 9 kWh PHEV battery pack is composed of standard-size 18650 cylindrical lithium-phosphate cells. Assuming a nominal module voltage of 14.6V, achieved by placing four 3.65V cells in series, 19 modules would be required to achieve OEMtek’s rated pack voltage of 277V.
Given the 9kWh rating of the pack, as well as packaging constraints, each module is probably composed of approximately 25 parallel strings of 4 cells, in series, for a total of 100 cells per module.
OEMtek’s BREEZ operates in a “piggyback” architecture, complementing the Toyota OEM NiMH hybrid pack. The BREEZ plug-in hybrid will average 90 miles per gallon at freeway speeds of 60 miles per hour for an average distance of 47 miles on a single charge, according to the company. For urban driving the vehicle will average more than 150 mpg at speeds under 35 mph for 30 miles on a single charge.
OEMtek says that its testing yields an all-electric range of 30-35 miles per full charge.
The BREEZ (Battery Range Extender EZ) fits over the tire in the trunk of the Prius, but does not use any of the trunk space.
OEMTEK’s core pack technology includes multiple safety systems, both passive and active, that monitor the level of charge and current of the battery cells. The system is controlled by an OEMtek proprietary smart battery management system (BMS). Logic circuitry and microcontrollers continually monitor voltage, current and temperature within the pack.
Initially the OEMtek product will only be available in California, where more than 500,000 Toyota Prius vehicles have been sold. OEMtek plans to install about 40 BREEZ systems in Toyota Priuses starting in March and will ramp up to 100 monthly conversions by the end of 2008. OEMtek plans to offer plug-in conversions of Ford’s Escape hybrid SUV in late 2008.
The initial BREEZ solution will cost in a range between $12,500 to $15,000.