[jws]

The pack is 53kWh according to wikipedia and discharges in 11 weeks from full according to the article. Unless I botched a decimal place, that is a 29 watt idle load. (53000 watt hours / (11 weeks * 7 days/week * 24 hours/day) ). In perspective, that is about the same as 4 night lights.

Clearly there is about 20 times that much power available at the end of a 100 foot extension cord in a standard household outlet.

Failure modes available:

• Was not actually plugged in.

• Was unplugged then plugged back in much later, possibly unbeknownst to owner. (Someone in my household unplugs my DVR to use an outlet. Grr.)

• Was on a switched outlet. (I once bought a new drill over that. Who knew one of the duplex outlets was switched and the other not? But the new drill wasn't $40k.)

• The Tesla charger could have a cutoff where it stops charging if unable to pull X amps where X is somewhere between 7 and 15. This could be either intentional or unintentional. Brown out protection circuitry, if needed by the design, could do this. They also might fear they are setting your house on fire by dropping 800+ watts somewhere in a wall and shut off.

• Broken charger.

• Broken extension cord.

[nash]

You forgot "Owner made up story"

[Vixter]

A roadster that is plugged in, is not really "off". It will provide power for heating or cooling of the battery pack if the temps get too high or too cold. This would be much more than a small idle load.