Tesla has responded in more detail to the case of the Tesla “brick,” where a blogger earlier this week wrote about several cases of early Roadsters that had been left without a charge for an extended period of time and had ruined their batteries. And Tesla says that for the Model S, Tesla’s electric sedan that will start shipping this Summer, it would take an entire year to fully discharge (and ruin) the battery, starting from a 50 percent charge.
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.
For the earliest Roadsters (like Roadster 1.5) Tesla says that it would take over two months to discharge the batteries without being plugged in. Tesla has continued to develop its battery management technology since Roadster 1.5 and also enables drivers to receive alerts if their battery charges get too low.
So, unfortunately folks, if you’re going to buy an electric car, you’re going to have to keep it plugged in for the time required.