Scaling the Supercharger network
The arrival of the Tesla Model 3 is the the electric-vehicle ecosystem’s make-or-break moment. With the Model 3, Tesla has solved the problem of delivering high EV range at low cost. If Tesla can deliver as promised, nothing more will be standing in the way of EV success.
That is, nothing except charging.
Today, electric cars follow the smartphone-charging model: plug in at home or work, do something else for a while (hours), and unplug. They’re different from gasoline cars, which follow a different “charging” model: go to a specialized facility, fill up quickly (minutes), and leave. The smartphone model works well only if everyone has their own charger that they don’t have to share, and the gas-car model works well only if there are so many gas stations that one is always nearby.
The 3 will still follow the smartphone model, which would be great if everyone buying a 3 had a dedicated home or work charger. But they won’t. The car costs less, so it is likely that more buyers will have lower incomes, so it is likely that more of them will have only apartment or street parking. Until either EV technology advances enough that EVs charge quickly (minutes), or until every work/residential parking space has a charger, this will be a problem.
Superchargers look a lot like gas stations, but they’re not. They’re still too slow, and they’re still too rare. They’re intended to give infinite road-trip range to a 250-mile-range EV, and for that purpose they’re good. But it’s likely that many 3 owners (like a few S owners today) will misuse them as their personal home chargers. On a small scale, this isn’t a big deal; in fact, so far it’s given Tesla some much-needed wiggle room. But on a larger scale, it could cause the collapse of our nascent EV ecosystem. The Supercharger network cannot be a home-charging solution for an EV selling in the millions.
How can Tesla continue to offer the incredible, indispensable Supercharger network in the face of a huge number of new EV owners who have no dedicated charging solution? How can Tesla continue its mission of creating a scalable, sustainable EV ecosystem?
This is a proposal that aligns the interest of every Tesla owner toward scalable, sustainable ecosystem growth.
Core Principles
Each member of the Tesla community should contribute to the health of the EV ecosystem.
The Supercharger network should be free to use as long as you’re not preventing others from using it.
The Supercharger network’s revenue structure should encourage congestion-reducing behavior.
Rules
For every kilowatt-hour you charge outside the Supercharger network, your Tesla receives one credit. This could be your home NEMA 14-50, a ChargePoint station, your employer’s J1772, a PlugShare down the street, or anything else that’s not a Tesla Supercharger.
For every minute you are plugged into a congested Supercharger, your Tesla pays one credit. Credits continue to be charged even if your car reaches its charge limit. If you run out of credits, charging stops.
Charging at a non-congested Supercharger is free.
An algorithm developed by Tesla Motors determines congestion. The mobile app, the car’s display, and the Superchargers themselves clearly indicate whether congestion pricing is in effect or likely to start/end soon.
You can buy more credits for your car. The price in 2016 should be about $10 for 60 credits. Revenue goes to Tesla Motors, which uses it to continue building out the Supercharger network.
Credits are non-transferable and expire after 180 days.
Example scenarios
Owner who drives 15,000 miles a year, charges 14,000 of those miles at home/work, and charges the remaining 1,000 miles at congested Superchargers. This owner will build up more than enough credits that the Supercharger usage will be free.
Nomadic owners who go on long (multi-week) road trips and charge only at Superchargers. These owners are unlikely to ever need to buy credits, because they will typically visit non-congested Superchargers. Like most road-trippers, they will also tend to use Superchargers efficiently (charging at maximum rate and vacating the station as soon as charging is complete) because they already wanted to get back on the road quickly.
Owners who frequently use local Superchargers during congested times. These owners will contribute money toward the network build-out. For example, consider an apartment dweller who drives 12,000 commute miles/year and tops off every weekday evening at a popular Supercharger. This would cost about $7/day (20 kW/h charge rate, 45 miles/day, 335 watts per mile = 45 minutes/day to charge) or about $1,800/year. Tesla would eventually add enough Supercharger capacity that the incidence of congestion would drop in this owner’s local area.
Same owner, but waiting until the battery was near-empty, thereby charging at the maximum Supercharger rate. A 30-minute stay at the Supercharger (about $5) would accrue enough charge for about three days of commuting, which would come to a very reasonable $430/year in charging costs (about the same as what the person in Example #1 pays in home electricity costs). This owner might find this usage pattern inconvenient and decide instead to invest that money in a NEMA 14-50 outlet near the apartment parking lot, in which case the owner becomes like Example #1 (all Supercharger usage is free).
It’s probably not legally possible to retroactively apply these rules to existing Model S/X owners, but even for them, the car UI could still display the credit balance, causing those owners to contemplate their usage patterns. But for future owners, a system like this would prevent a looming tragedy of the Supercharger commons.