The devil is in the details…
Wayne Gerdes - CleanMPG
- April 16, 2010
Prius PHEV-13 animation cutaways and capabilities.
Currently, HEVs, PHEVs and BEVs in both production and prototype form are being demonstrated or announced from almost every major manufacturer on almost a weekly basis as of late. There is however just one company that has supplied the most fuel efficient hybrid automobile on the planet through a second and third generation over the past 6-years. That being Toyota and the ubiquitous Prius.
Not only does Toyota have the experience to place both a modern and reasonably priced high fuel economy hybrid in our hands but is laying the groundwork for their own future with the launch of the 600 PHEV equipped Prius PHEVs which after the fleet trial, will be available to the public by 2012.
Li-Ion, what’s that
Li-Ion battery electrodes are composed of lightweight lithium and carbon. Lithium is a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds. This translates to excellent energy density in a small, lightweight package. If you have a cell phone, iPod or almost any other portable electronic device, you've seen Li-Ion batteries in action.
Li-Ion batteries are promising for BEV and PHEV applications that require higher energy density to meet the higher demands of charge depleting operation (large swings in the battery state-of-charge). It is important to note that although Li-Ion batteries are less expensive in terms of materials, they are more expensive than NiMH batteries in terms of production costs. Li-Ion batteries require higher quality-control, often including clean-room production facilities, which increases the overall cost of production.
Toyota began Li-Ion battery research and development in the mid 1990s. A Li-Ion stop/start battery was used in the Vitz, which went on sale in Japan in 2003. The battery powering the current Prius Plug-in Hybrid (PHEV) demonstration program vehicle is the first Li-Ion drive-battery developed by Toyota and its joint venture battery production company, Panasonic Electric Vehicle Energy (PEVE). In early November 2009, PEVE began producing the first of more than 600 Prismatic based, Li-Ion batteries on a dedicated assembly line at its Teiho production facility in Japan.
This first-generation Li-Ion battery was placed in 150 conventional hybrids (mostly Prius’) and logged well over a million combined miles. In the end, the battery was deemed both reliable and durable, confirming that it could be used in a conventional hybrid application, depending on further developments in cost reduction.
2011 Prius PHEV-13 details
The Toyota Prius PHEV utilizes Toyota’s first-generation Li-Ion for propulsion. Thanks namely to Li-Ion’s reasonably high energy density and light weight, these batteries are a good choice for electric vehicles of all types over the near term.
The 2010 Prius has one NiMH main battery pack that weighs 110 pounds. This pack contains 168 individual 1.2 V cells wired in series with a nominal voltage of 201.6 V DC. The 2010 Prius PHEV has three Li-Ion battery packs, one main and two additional packs (pack one and pack two) with a combined weight of 330 pounds. Each battery pack contains 96 individual 3.6 V cells wired in series with a nominal voltage of 345.6 V DC.
When the PHV is fully charged the two additional battery packs supply power to the electric motor. Pack one and pack two operate in tandem with main battery pack but only one at a time on the individual circuit. When pack one’s battery’s charge is depleted, it will disconnect from the circuit and pack two will engage and supply electrical energy to the drive line. When pack two has depleted it will disconnect from the circuit and the vehicle will operate like a regular hybrid. Pack one and pack two will not reengage in tandem with the main battery pack until the vehicle is plugged in and charged.
The Prius PHEV’s larger HV battery assembly requires additional “air only” cooling. The vehicle is equipped with three battery-cooling blowers, one for each of the three battery packs. Each battery pack also has an exclusive intake air duct with one cooling blower taking care of the needs of the DC/DC converter.
Each pack (all three are exactly the same) includes (42) temperature sensors, (3) Battery control modules and (3) System Main Relays (SMR’s).
While Toyota has mentioned 220 V charging in under 1.5 hours, the Prius PHEV-13 fleet demonstrators will not be 220V capable.
In addition, the Fleet Prius PHEVs include no EV button to remove and then reinitiate EV mode in order to save it when it can possibly be used more effectively. The US engineering teams have had face to face discussions with their Japanese counterparts detailing the reasons why this would be useful for the US consumer and it is expected that Consumer based production units available in 2012 will include the EV button capability.
Conventional w/ EV, EV Driving Ratio and EV HSI
The new MFD is similar to the current Prius with the addition of the EV icon in the standard display. The Energy and Consumption screens now contain an EV-Range with the HSI changing from an open space all the way across to the standard center threshold bar when EV-Mode has been consumed in its entirety. One more screen was added which displays EV vs. Gasoline ratio over any number of accumulated miles shown underneath the screen.
2011 Prius PHEV Exterior
The Fleet PHEVs exterior color is unique to the Toyota lineup. In addition, the fleet vehicles include a lower body Plug-In Hybrid graphic and silver highlights on the door handles, mirrors and across the split rear window.
As equipped, the vehicle represents a significant enhancement of Toyota's Hybrid Synergy Driveฎ (HSD) system. It combines the high-output Li-Ion batteries with HSD technology to offer an expanded fully electric driving capability. The Prius Plug-in Hybrid can be recharged in approximately three hours from a standard 110V electrical outlet or one and a half hours with a 220V connection.
The Prius Plug-in Hybrid's lithium-ion battery pack ensures strong, seamless acceleration up to highway speeds of more than 62 mph on electric-only power. Drivers have experienced over 70 mph before the ICE actually spins up so there is a torque dependant characteristic to this specification. With a fully charged battery, the PHEV can travel over 15-miles in EV mode in our experience. Once the EV-mode charge is depleted, the vehicle defaults to normal, full-hybrid mode and operates exactly like a regular Prius.
In the past, issues such as weight, size and cost of the large capacity batteries required to offer satisfactory EV range, and the lack of adequate public recharging infrastructure have been barriers to mass-market electric vehicle acceptance. In designing the Prius Plug-in Hybrid, Toyota is addressing some of these issues. Given current battery development progress and costs, Toyota sees plug-in hybrid vehicles as the most realistic way to use grid electrical power for vehicle propulsion.
Max. Output: 98 HP@5200 RPM
Max. Torque: 105 Lb-Ft@4000 RPM
Motor Type: Permanent magnet synchronous motor
Max. Output: 80 HP
Max. Torque: 153 lb-ft.@0 RPM
Battery Type: Li-Ion
Maximum EV Cruising Range: ~ 14 miles
Recharging Time: 3 hours @ 110V