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DC fast charging not as damaging to EV batteries as expected

As convenient as DC fast charging is, there have been lots of warnings that repeated dumping of so many electrons into an electric vehicle's battery pack in such a short time would reduce the battery's life. While everyone agrees that DC fast charging does have some effect on battery life, it may not be as bad as previously expected. Over on SimanaitisSays, Dennis Simanaitis, writes about a recent presentation by Matt Shirk of the Idaho National Laboratory (INL) called DC Fast, Wireless, And Conductive Charging Evaluation Projects (PDF) that describes an ongoing test of four 2012 Nissan Leaf EVs that are being charged in two pairs of two. One pair only recharges from 50-kW DC fast chargers, which the other two sip from 3.3-kW Level 2 chargers exclusively. Otherwise, the cars are operated pretty much the same: climate is automatically set to 72 degrees, are driven on public roads around Phoenix, AZ and have the same set of dedicated drivers is rotated through the four cars. "Degradation depends more on the miles traveled than on the nature of recharging." What's most interesting are the charts on page seven of Shirk's presentation (click the image above to enlarge), which show the energy capacity of each of the four vehicles. When they were new, the four batteries were each tested to measure their energy capacity and given a 0 capacity loss baseline. They were then tested at 10,000, 20,000, 30,000 and 40,000 miles, and at each point, the DC-only EVs had roughly the same amount of battery loss as the Level 2 test subjects. The DC cars did lose a bit more at each test, but only around a 25-percent overall loss after 40k, compared to 23 percent for the Level 2 cars. Simanaitis' takeaway is that, "INL data suggest that the amount of degradation depends more on the miles traveled than on the nature of recharging." The tests are part of the INLs' Advanced Vehicle Testing Activity work and a final report is forthcoming. These initial numbers from IPL do mesh with other research into DC fast charging, though. Mitsubishi said daily fast charging wouldn't really hurt the battery in the i-MiEV and MIT tests of a Fisker Karma battery showed just 10-percent loss over 1,500 rapid charge-discharge cycles.

The Carlos and Dieter Show promises more collaboration

Daimler and Renault-Nissan said Friday the automakers have expanded their four-year-old alliance to include putting a Renault diesel in the Mercedes C-Class, a Mercedes gasoline engine in an Infiniti and possibly will involve automated driving technologies in the near future. At a joint Paris Motor Show press conference dubbed 'The Carlos and Dieter Show' by European media, Renault-Nissan CEO Carlos Ghosn and Daimler CEO Dieter Zetsche said the alliance between the automakers is running strong and will expand into any area that makes financial sense for both companies.
Ghosn and Zetsche said the alliance between the automakers is running strong and will expand into any area that makes financial sense for both companies.
Daimler and Renault-Nissan began their partnership in 2010 with plans to collaborate on three projects. They've since expanded that and are working on 12 projects together, including building a joint plant in Aguascalientes, Mexico. Renault-Nissan and Daimler are launching their first vehicles developed together from scratch: the Renault Twingo (which went on sale in September) and the new Smart Fortwo and Smart Forfour, which go on sale in November.

Nissan Leaf battery cells put through torture test, live to charge again

One minor chink in the armor of the Tesla Model S is that a small number have caught fire, once their battery packs were penetrated. Nissan Leaf drivers, however, might just be able to weather such an event without an ensuing CarBQ. Our evidence for such a claim? A video that has surfaced of cells from a Leaf pack undergoing a battery of torture tests (pun somewhat-ashamedly intended). Shared by folks at the Hybrid Auto Center in Las Vegas – who offer for sale, among other things, used Leaf lithium battery modules – the footage shows salvaged cells being brutally assaulted with a screwdriver, and later, a propane torch. Granted, these tests are not the same thing as flinging a piece of metal into a working pack at 70 miles per hour, but they do claim to show that a puncture does not always equal a fire. Oh, and don't try this at home. When pierced through by the flat head tool, there is no explosion or eruption of flame. Instead, a rather modest wisp of smoke shyly emerges as the electrolyte next to the shorted area of the fully-charged foil pouch reacts with the influx of oxygen. Again and again, the blade descends, until the cell is riddled with holes. No fire. Amazingly, when connected with a voltmeter afterward there are still plenty of signs of life, and when it is charged and discharged (off-camera), it reportedly suffers only a slight loss of charge capacity. The video goes on to show another cell attacked with open flame with similar results. While the demonstration is, perhaps, somewhat crude, the message it sends is loud and clear: lithium batteries can be safe and rather robust, despite some freak accidents. Scroll below to watch the short presentation for yourself. This content is hosted by a third party. To view it, please update your privacy preferences. Manage Settings.