Tesla Motors’ Devastating Design Problem

Tesla Motors’ lineup of all-electric vehicles — its existing Roadster, almost certainly its impending Model S, and possibly its future Model X — apparently suffer from a severe limitation that can largely destroy the value of the vehicle. If the battery is ever totally discharged, the owner is left with what Tesla describes as a “brick”: a completely immobile vehicle that cannot be started or even pushed down the street. The only known remedy is for the owner to pay Tesla approximately $40,000 to replace the entire battery. Unlike practically every other modern car problem, neither Tesla’s warranty nor typical car insurance policies provide any protection from this major financial loss. Here’s how it happens.

Despite this “brick” scenario having occurred several times already, Tesla has publicly downplayed the severity of battery depletion risk to both existing owners and future buyers. Privately though, Tesla has gone to great lengths to prevent this potentially brand-destroying incident from happening more often, including possibly engaging in GPS tracking of a vehicle without the owner’s knowledge. UPDATE!

NOTE (UPDATED!): The argument outlined in this story by Michael DeGusta that originally appeared on theunderstatement.com has been confirmed by Tesla with the following statement:

All automobiles require some level of owner care. For example, combustion vehicles require regular oil changes or the engine will be destroyed. Electric vehicles should be plugged in and charging when not in use for maximum performance. All batteries are subject to damage if the charge is kept at zero for long periods of time. However, Tesla avoids this problem in virtually all instances with numerous counter-measures. Tesla batteries can remain unplugged for weeks (even months), without reaching zero state of charge. Owners of Roadster 2.0 and all subsequent Tesla products can request that their vehicle alert Tesla if SOC falls to a low level. All Tesla vehicles emit various visual and audible warnings if the battery pack falls below 5 percent SOC. Tesla provides extensive maintenance recommendations as part of the customer experience.

— Ed.

How To Brick An Electric Car

A Tesla Roadster that is simply parked without being plugged in will eventually become a “brick”. The parasitic load from the car’s always-on subsystems continually drains the battery and if the battery’s charge is ever totally depleted, it is essentially destroyed. Complete discharge can happen even when the car is plugged in if it isn’t receiving sufficient current to charge, which can be caused by something as simple as using an extension cord. After battery death, the car is completely inoperable. At least in the case of the Tesla Roadster, it’s not even possible to enable tow mode, meaning the wheels will not turn and the vehicle cannot be pushed nor transported to a repair facility by traditional means.

The amount of time it takes an unplugged Tesla to die varies. Tesla’s Roadster Owners Manual [Full Zipped PDF] states that the battery should take approximately 11 weeks of inactivity to completely discharge [Page 5-2, Column 3: PDF]. However, that is from a full 100% charge. If the car has been driven first, say to be parked at an airport for a long trip, that time can be substantially reduced. If the car is driven to nearly its maximum range and then left unplugged, it could potentially “brick” in about one week.[1] Many other scenarios are possible: for example, the car becomes unplugged by accident, or is unwittingly plugged into an extension cord that is defective or too long.

When a Tesla battery does reach total discharge, it cannot be recovered and must be entirely replaced. Unlike a normal car battery, the best-case replacement cost of the Tesla battery is currently at least $32,000, not including labor and taxes that can add thousands more to the cost.

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