Does an extensive electric vehicle public charging network really make sense?
The typical Nissan Leaf driver's daily trip is just 31 mi (50 km), according to Brendan Jones, Director of EV Infrastructure Strategy and Execution, Nissan. Further, the 2013 model has the 220-V 6.6-kW charge system, which reduces charge time from eight to four hours, so a home system would seem to be adequate. The 6.6-kW, introduced on the Ford Focus EV, is standard on the middle and high-level Leaf models (SV and SL) and optional on the new entry-level Leaf S, which has a 3.6-kW charger, the one available on all previous models. The S is the model that will carry the $199/month advertised lease price and a base purchase price of about $29,000.
However, Nissan is working aggressively on a public network, including deployment of dc fast charging, Jones said, speaking recently at a meeting of the International Motor Press Association (IMPA) in New York City. The intent, he said, "is to replace range anxiety with range confidence."
Leaf sales lead the EV industry but—at 27,000 since 2011—are still modest. The importance of EV sales for CAFE (corporate average fuel economy) credits is well-known (each EV sale counts as two vehicles in 2017-19, 1.75 vehicles in 2020, and 1.5 vehicles in 2021), but for Nissan there is an additional factor. The car and its battery pack now also are being made at the company's U.S. manufacturing facilities in Smyrna, TN.
DC fast-charge has high take rate
But is a public network really going to be used?
Jones explained that 75% of Leaf buyers have the $1300 package that allows for dc fast-charging, based on the Japanese CHAdeMO standard, to raise state of charge (SOC) from 20% to 80% in 30 min. In addition, where Nissan has installed CHAdeMO stations in public facilities, the usage rate has been very high—350 to 400 per month—and Leaf owners have told Nissan of the confidence factor, the "if I need it, I know it's there" attitude.
The average Leaf that hooks up is at 35-40% state of charge, Jones said, which reasonably corresponds with when drivers of gasoline-powered cars pull in to refuel. Although the original marketing for the Leaf was to residents of private homes with an accessible outlet for charging, Nissan now is looking to expand the market to apartment dwellers by building enough public facilities to demonstrate that the Leaf could be charged entirely at them. Some urban commercial vehicles also might fit that pattern, including taxis.
A pilot fleet of six Leafs has just been launched in New York City to test the EV taxi concept. Nissan has a franchising agreement with the city for Nissan NV200 gasoline-engine vans as taxis, due to begin this fall, and a promise to offer EV versions, with a goal of 20% EV taxi penetration by 2020. The pilot program will include strategically located CHAdeMO and SAE Level 2 (220-V) stations.
Does the fact that CHAdeMO is not compatible with the SAE J1772 dc fast-charge combo connector create an infrastructure issue? No, Jones said. "The big cost is getting power to the spot. There can be any connector installed there. We're talking to other OEs and we know we can install CHAdeMO and SAE combo connectors in the same station."
Jones was asked whether the Leaf's air-cooled battery pack really tolerates dc fast-charging. He said he would not question the use of liquid cooling on other vehicles, such as the Ford Focus and Chevrolet Spark EVs as well as the Chevy Volt plug-in. Their engineers point to liquid cooling as the best way to fast-charge without causing temperatures to rise to levels that would affect cell life.
However, Jones told the IMPA meeting, Leaf cells are of a thermally stable lithium-ion-manganese chemistry, and they are prismatic (flat) so they dissipate heat quickly. He added that Nissan has not identified an issue. The cells will accept fast-charge while the electronic control system monitors pack temperatures and will not allow them to exceed a safe value, Jones said. He declined to provide specifications.
The charging stations were free-use, but the high usage rate raised the question of what would happen if a fee were imposed, as most private charging station operators are expected to do. So Nissan set a $5 tab per connection at some stations. There was an initial 30% drop in usage, Jones said, but the stations quickly recovered and now are running at their previous rate.
Lease-like battery program
Nissan also is addressing the range anxiety issue with a new battery capacity depletion assessment program that supplements the existing warranty. The program, which begins next year, with details to be announced then, is modeled after European Leaf programs, where the battery pack is leased separately. Eventually, the program will offer replacement with the latest-technology battery pack, for approximately $100 mo, if the pack capacity drops below 70%. The initial replacement will be with a new or remanufactured pack.
The present U.S. Leaf warranty is for five years/60,000 mi (97,000 km) for a minimum of 70% capacity, and eight years/100,000 mi (161,000 km) against defects. The Leaf battery charge indicator is 70% or higher if it shows nine or more bars. There also is an extended battery warranty available in the U.S. that provides similar (70% capacity) coverage.
A number of 2013 model product improvements were made to raise the U.S. EPA-rated EV range from the previous 73 mi (117 km) to a projected 83 mi (134 km), including a reduction in coefficient of drag from 0.29 to 0.28. One of the most significant is use of a heat pump for HVAC, including cabin heating, plus zoning to increase individual perceived comfort, using small resistance heaters for the steering wheel and at all seating positions.
Although air-conditioning in hot weather is a major power draw, the PTC (power temperature coefficient) resistance heaters for cabin air heating have been shown to be a major reason for loss of range in winter. An analysis by the U.S. National Renewal Energy Laboratory of Mitsubishi i-MIEV data on resistance heaters for cabin air showed a 46% reduction in range even in "ECO" mode, 68% with the heat on high.
The driver of an SV or SE also will be able to select a more aggressive regenerative braking mode ("B" position on the shift lever). This is in addition to the ECO mode, which increases regeneration and also reduces performance and HVAC output.
There will be no "Tesla-like" EV from Nissan, Jones told the meeting, noting the approximate $100,000 price point. "We think we're in the right part of the market with the Leaf," he said, adding that total sales presently were running over 2000/month.