Tag archives for Car Safety
‘Revenge of the Electric Car’ premiere: Elon Musk arrives in a Tesla Roadster
Tesla Motors CEO Elon Musk is hardly shy and retiring.
He tweets out random financial results, states as fact things that haven’t quite happened yet, and regularly speaks his mind.
Yesterday, he described the troubled Boeing 787 Dreamliner’s battery pack design as ‘inherently unsafe,’ which could add fuel to the…ahem…fire.
It came just one day after his offer to help Boeing resolve its problem with fires in the 787′s lithium-ion packs, designed by Japanese battery-cell company GS Yuasa.
(It’s worth noting that SpaceX, the other company Musk runs, competes directly with Boeing for certain government contracts for space-launch vehicles.)
Musk, who has run Tesla Motors [NSDQ:TSLA] for several years, laid out his thoughts on battery design in a detailed e-mail to the website Flightglobal.
In it, he termed the architecture of the GS Yuasa battery packs supplied to Boeing “inherent unsafe,” and predicted more fires from the same causes due to its design.
Specifically, Musk criticized the use of large-format lithium-ion cells “without enough space between them to isolate against the cell-to-cell thermal domino effect.”
He also noted that when thermal runaway occurs in the larger cells, more energy is released by the single cell than comes from a small-format “commodity” cell, of the type used by the thousands in Tesla battery packs.
And he went on to highlight what he viewed as the dangers of batteries using those large-format cells, saying they have a “fundamental safety issue” because it’s harder to keep the internal temperature of a large-format cell consistent from the center to the edges.
Not surprisingly, Mike Sinnett–Boeing’s chief engineer for the 787 project–counters that the company designed the pack to cope with not only a single cell failure but to contain runaway thermal events as well.
The 787 battery problems have sparked a deluge of news coverage, with the Seattle Times noting yesterday that Boeing had numerous problems with the batteries before the fires that led to the grounding of all 787 planes worldwide.
Boeing 787 Dreamliner
The chemistry used in the Boeing 787 cells is not the same as that used in today’s electric cars, a point largely overlooked by many reporters.
But Musk’s comments highlight a second issue: the use of large-format lithium-ion cells (some roughly the size of a very thin paperback book) versus the smaller commodity cells (somewhat larger than a AA battery) that Tesla uses.
Musk’s critique, although he didn’t explicitly say so, could be extended beyond the 787 Dreamliner to indict the pack design of all electric cars that use large-format lithium-ion cells.
Those include, oh, every single modern plug-in electric car except the Tesla Model S.
Tesla Motors is the sole maker that builds its packs out of thousands of small ‘commodity’ lithium-ion cells (from Panasonic, for the Model S) rather than using hundreds of large-format cells.
Battery-pack engineering is a complex, multifaceted art.
There’s the physical design of a large, heavy component that must be engineered into the vehicle’s structural design.
There’s positioning of the cells inside the pack to protect against thermal runaway.
Tesla Motors – Model S lithium-ion battery pack
There’s thermal conditioning, in which a pack is passively or actively heated or cooled to keep its cells within a desired temperature range, both extending their life and reducing the chance of catastrophic cell failure.
Each electric-car maker takes a somewhat different approach: Nissan uses just passive cooling in its Leaf battery electric car, but has had no recorded fire incidents at all to date.
It has, however, had problems with reduction in energy capacity early in the life of cars that cover high mileages in high temperatures.
The Chevrolet Volt, on the other hand, uses only two-thirds of its pack energy and has active liquid cooling for its pack (as does the Model S).
So has Musk has implicitly slammed the pack designs of the Nissan Leaf, Chevrolet Volt, and a host of other electric cars with battery packs of 16 kilowatt-hours or more?
If so, is this a good strategy for the CEO of a startup electric-car maker?
Leave us your thoughts in the Comments below.
Modern cars feel so substantial and safe they can often feel impregnable–you’re just rolling along in your little bubble, protected from the world outside.
The Model S, the luxurious electric car from Tesla Motors [NSDQ:TSLA] with its large body, incredible refinement and luxurious interior is just such a vehicle–though as the video above (via Wired) demonstrates, there’s only so much extreme force a car can handle.
No car is completely crash-proof, and it can take the work of a split-second out on the road for something to go very, very wrong.
If it does, modern cars really are as safe as they feel, with airbags, deforming crash structures and more, keeping occupants as safe as possible.
But put enough force through a car body and occupants can still become trapped, or incapacitated to such an extent that safety teams need extraction tools like the “jaws of life” to provide better access for ambulance crews.
In an electric car, there’s an element of added danger for those crews, with high voltage cables and different body structures to contend with.
It might be excruciating to watch the Model S torn apart, bit by bit, but reassuring to know that if the worst happens, the emergency services still have a way of extracting you from the car.
In the video above, the real action starts around the 27-minute mark, as safety crews rip the front passenger door from its frame. They then remove the front wing and hood, before making cuts into the A-pillar, chassis support struts and finally, the door surround–careful to avoid the electric components nearby.
All this accomplished, some dashboard support struts are cut, before a hydraulic ram pushes the dashboard upward. The resulting gap could be enough to free an injured passenger’s legs following a crash–or to give paramedics a larger space to extract a passenger with back or neck injuries.
Tesla itself provided the Model S for Fremont Fire Department to train on–and the resulting video can be used to train other crews to deal with the car.
The rest of the video goes through all the realities and myths faced by first responders to electric vehicle accidents–and it’s worth a watch to fully reassure you of the safety of these vehicles.