The Tesla Roadster Battery Controversy

Electric vehicle enthusiasts are dismayed at reports that Tesla’s much-touted Roadster, if left unplugged for as little as a few weeks, could experience catastrophic battery failures, costing owners tens of thousands of dollars.

The initial reporting on the issue came from Michael DeGusta, who runs The Understatement blog. In the original post, DeGusta outlines what he considers a serious design flaw in the original Tesla Roadster: should the battery ever be totally discharged, he says it renders the vehicle immobile and has to be replaced — at a cost of approximately $40,000.

The source of the problem: the parasitic load from the vehicle’s subsystems drains the battery. If it’s left unplugged, this can drain the battery. That leaves the vehicle completely inoperable. The wheels won’t even turn, so the car can’t be pushed or towed by traditional means.

Tesla has since responded on its own blog, downplaying the problem and reminding drivers that the owners’ manual repeatedly warns about leaving the Roadster unplugged for extended periods of time. The vehicles themselves warn owners if their battery is running too low with repeated visual reminders. Other bloggers have also weighed in, essentially saying it’s the owners’ fault if this happens to them, because these new types of batteries require more attention.

Even if the vehicles are left sitting without a fully charged battery, it can take months or even up to a year to discharge the unit:

The earliest Roadsters will take over two months to discharge if parked at a 50 percent charge without being plugged in. From that starting point, Tesla has consistently innovated and improved our battery technology. For example, a Model S battery parked with 50 percent charge would approach full discharge only after about 12 months. Model S batteries also have the ability to protect themselves as they approach very low charge levels by going into a “deep sleep” mode that lowers the loss even further. A Model S will not allow its battery to fall below about 5 percent charge. At that point the car can still sit for many months. Of course you can drive a Model S to 0 percent charge, but even in that circumstance, if you plug it in within 30 days, the battery will recover normally.

The Understatement remains unimpressed.

Beyond the issue of customer care and feeding of the EV battery, the various blogs writing about the bricking problem also note that Tesla apparently has the ability to track customer locations. There are also claims that a service manger even used this ability (without notifying the owner) in order to intervene and prevent a battery failure on at least one occasion.

Another key point that vehicle designers may want to consider: Is there some way to make these vehicles easier to manage in the case of a battery failure in general? Because these cars have electronic transmissions, there’s no way to put them in neutral with a dead battery. I have a 2006 Prius, and if the regular 12-volt battery goes dead while the car is parked nose-in to the garage, just jump starting it requires crawling into the back seat, manually releasing the trunk latch, then partly disassembling the cargo compartment in order to access the battery.

Is there a better way forward for EV batteries?

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