!!c1QfXUgcGY0-“It’s A Brick” – Tesla Motors’ Devastating Design Problem

February 21 ,2012

“It’s A Brick” – 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 — 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.

This is an interesting post, which you’ll probably want to read in full. But there’s two paragraphs I’m confused about:

As a second Roadster owner discovered, the Tesla battery system can completely discharge even when the vehicle is plugged in. This owner’s car was plugged into a 100-foot long extension cord for an extended period. The length of this extension cord evidently reduced the electric current to a level insufficient to charge the Tesla, resulting in another “bricked” Roadster.

A standard 15 amp extension cable uses 14 AWG wire, which has a resistance of 2.525 milliohms per foot. Multiply by a hundred, (feet) divide by a thousand (mOhm to Ohm) and we have a total resistance of .2525 ohms. Plugging that into Ohm’s Law, assuming the worst case of drawing 15 amps quiescent load, and solving for voltage, we get a voltage drop of 3.78 volts. Which will drop a 120 volt circuit to 116.21 volts.

I… really doubt that would make a charger stop working. Either the circuit was overloaded, or the plugs weren’t fully engaged, and were adding resistance.

A fourth customer shipped his Tesla Roadster to Japan, only to discover the voltages there were incompatible. By then, it was too late, the car was bricked, and he had to ship it back to the US for repairs.

~~What? Japan uses the American standard— they even use NEMA 15 plugs.~~ Or not!

The full article provides five examples. When you remove these two dubious ones, and the one that the source couldn’t actually provide details for, we’re left with just two examples… of people who left their hundred-thousand-dollar electric cars unplugged for weeks at a time.

Granted, Tesla could really stand to make their manuals more explicit on the absolute need to keep the battery pack fully charged at all times; but this just does not seem like A Big Problem.

3:21pm |

(Notes:365)