Tesla started installing its first charging stations about the same time it began selling the Model S in 2012. Over the years, the Supercharger network has become one of the best charging networks in the world. It’s also among the biggest when considering the number of DC fast-charging posts. The seamless integration with Tesla vehicles provides a strong incentive to choose Tesla over other electric vehicle brands.

In recent years, the EV maker has expanded the Supercharger network at neck-breaking speeds. Still, it has always been careful to preserve the high quality and reliability of its chargers. While EV owners could rarely rely on third-party networks, which often lead drivers to non-functional chargers, Tesla Superchargers are almost always working. This has led to an uptime of nearly 100%, with the lowest rate of the past five years (99.74%) in 2020 during the pandemic.

Tesla released the 2023 Impact Report on Thursday, and sure enough, there was a section dedicated to the Supercharger reliability. Tesla advertises its Supercharger network with the line “Chargers that just work,” with an uptime rate of 99.97% in 2023. If this reminds me of the unanimous votes in totalitarian countries, which rarely reflect reality, it is because Tesla uses some shady method to assess the uptime.

Don’t get me wrong. I am sure that Tesla Supercharger has one of the best reliability scores in the industry. However, the way Tesla presents it casts a shadow on the report and makes people question its accuracy. According to a slide in the 2023 Impact Report, the uptime of Superchargers sites reflects “the average percentage of sites globally that had at least 50% of their daily capacity functional for the year. “

That’s a very low bar if you ask me, and confusing as hell. According to this metric, a whole Supercharger site can be down every day for 11 hours and still counts as 100% uptime. Or half the stalls at a station could be down the whole year, and it gets the same result. Even if the Superchargers have the best uptime rates, you wouldn’t know if a single stall in the network had a 50% uptime or 100%. This is a rather strange definition of uptime.

Moreover, it is difficult to compare these numbers with those of other companies if they don’t use the same metric. Again, I’m sure Tesla Superchargers are the golden standard, with better uptime than every other charging network in the world. However, the way Tesla presents this information doesn’t do it justice.