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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.

Takata air bag recall list

The National Highway Traffic Safety Administration confirmed yesterday that 33.8 million vehicles with Takata airbags are going to be recalled. It's the largest recall in automotive history. The already record-breaking rate of automotive recalls this year shows no signs of slowing down, especially since millions of cars with defective airbags made by global supplier Takata are under ongoing scrutiny. The federal government is warning owners that inflator mechanisms in the air bags can rupture, causing metal fragments to fly out when the bags are deployed. The faulty air bags have already been blamed for multiple deaths. How do you know if your vehicle is safe? The National Highway Traffic Safety Administration released an updated list of vehicles under recall. Sometimes however, the government's website will crash and the list may not be complete. Check your VIN at the NHTSA website to make sure. The list of cars affected by the recall has not been released, but seem to span multiple models over the years for many of the automakers.

Is the skill of rev matching being lost to computers?

If the ability to drive a vehicle equipped with a manual gearbox is becoming a lost art, then the skill of being able to match revs on downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. The usefulness of rev matching in street driving is limited most of the time – aside from sounding cool and impressing your friends. But out on a race track or the occasional fast, windy road, its benefits are abundantly clear. While in motion, the engine speed and wheel speed of a vehicle with a manual transmission are kept in sync when the clutch is engaged (i.e. when the clutch pedal is not being pressed down). However, when changing gear, that mechanical link is severed briefly, and the synchronization between the motor and wheels is broken. When upshifting during acceleration, this isn't much of an issue, as there's typically not a huge disparity between engine speed and wheel speed as a car accelerates. Rev-matching downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. But when slowing down and downshifting – as you might do when approaching a corner at a high rate of speed – that gap of time caused by the disengagement of the clutch from the engine causes the revs to drop. Without bringing up the revs somehow to help the engine speed match the wheel speed in the gear you're about to use, you'll typically get a sudden jolt when re-engaging the clutch as physics brings everything back into sync. That jolt can be a big problem when you're moving along swiftly, causing instability or even a loss of traction, particularly in rear-wheel-drive cars. So the point of rev matching is to blip the throttle simultaneously as you downshift gears in order to bring the engine speed to a closer match with the wheel speed before you re-engage the clutch in that lower gear, in turn providing a much smoother downshift. When braking is thrown in, you get heel-toe downshifting, which involves some dexterity to use all three pedals at the same time with just two feet – clutch in, slow the car while revving, clutch out. However, even if you're aware of heel-toe technique and the basic elements of how to perform a rev match, perfecting it to the point of making it useful can be difficult.