Dealing with battery capacity loss in a Tesla Model S

The capacity of older Tesla Model S batteries degrades a little quicker than newer ones. That's the roundabout conclusion Green Car Reports writer and 2013 Model S owner David Noland made when studying capacity levels of his electric vehicle's battery. Nolan discovered that, at 34,000 miles, his battery had degraded about 12 percent. According to a 2014 study, the battery capacity in a Model S is likely to degrade at about six percent after 50,000 miles. Noland chalked the degradation up to what he called a three-month-long Supercharging "binge."

He then took a technician's advance by draining the battery to almost zero percent and the recharging it slowly. Doing so restored two kilowatt hours of capacity.

Ultimately, Nolan took the car in and found out that the original battery had a bad contactor mechanism as well as some corrosion. Fixing that has since prevented further degradation, but his battery still has degraded about eight percent to 70 kWh (the "true," i.e., usable, capacity of an 85-kWh battery is believed to be about 76 kWh).

Nolan notes that, according to a separate 2014 study, a Nissan Leaf's battery is likely to suffer a three-percent drop in capacity after 40,000 miles and extensive fast-charging usage, so his Tesla battery loss remains greater.

We'd last reported on Mr. Noland in March, when he'd complained in Green Car Reports that the brake and gas pedals were too close together and created simultaneous engagement issues that lengthened stopping distance. In other words, he's the kind of Model S owner who pays close attention to what's happening with his EV.