[ad#post_ad]GM engineers have rightly been assiduously concerned and careful about ensuring the Chevy Volt's battery will last 10 years or 150,000 miles and deliver its stated range and power.
The Nissan LEAF electric car, also expected to arrive at the end of the year, apparently isn't so meticulously engineered. Or so says Wired.com in an article written by Daryl Siry, former marketing head of Tesla and currently an advisor to Coda Automotive
Siry portrays Nissan almost as a brazen bull in a china shop fearlessly led by an overoptimistic and headstrong Carlos Ghosn. Nissan, Siry notes, now at the forefront of EV marketing wasn't even part of the discussion two years ago. This rush to the front lines may have made them less careful in their haste.
Ghosn reportedly said, “The engineers will always tell you, ‘Wait a little more,’ and if you keep playing this game, you never launch any product.”
Siry points out that the LEAF's 100 mile estimated range is based on the overly conservative LA4 test cycle, and that in real world conditions range will be "significantly less."
It gets worse.
Nissan is not using an active thermal management system for the LEAF's batteries.
Instead of including a separate high-tech computer controlled liquid heating and cooling system like the Volt has, Nissan is simply blowing cabin air into the pack with a fan. It is this sophisticated pampering of the pack GM feels is so critical for maintaining range, power and longevity, that Nissan has ignored completely. In fact GM has gone so far as to call pack construction core competency and has built and begun operating its own battery pack assembly plant.
Nissan director Mark Perry went so faras to dismiss the importance of a thermal management system.
“We don’t need thermal management for the U.S. ... we've gone on the record saying that the pack has a 70 to 80 percent capacity after 10 years,” he told Wired.com
Another Nissan product manager told Wired the real reason there is no thermal management system is that it would take up too much cabin space, by adding height to the pack. This is the reason Volt has four seats, compared to the LEAF's five.
GM's Volt executive Tony Posawatz explained why separate battery HVAC is so important in electric cars.
"Thermal management has bookend issues to manage: minimized power at low temperatures and life reduction at high exposure to higher temperatures,” he told Wired. “If you want to replace your battery every four to five years and someone is willing to pay for [a replacement battery], either the customer or the manufacturer, a modest or minimal HVAC system may work.”
It is quite likely Nissan's awareness they are taking a battery shortcut has led them to the decision to lease the battery separately.
Source ( Wired )