Tesla Charger Network is Resilient

[Missile Toad]

I saw this post, where one of the Tesla owners had extremely bad luck at two Superchargers. Since I've been studying this issue for the last 6 months, I have a rough estimate of the probabilities that a SuperCharger site experiences problems on any given day.

I have been daily checking/logging my Nav for Tesla-reported outages (Reduced Service / Temporarily Closed) since the beginning of the year. I skipped looking during my vacation, and sporadically through the year. I have a slight tendency to overlook outages, perhaps missing about 5% (stare at 300+ red pins, and you'll see what I mean). Sometimes, looking at the Nav, its like finding a red needle in a haystack of rose-colored needles. To compensate, I add 18 to my count of 362 daily, cumulative outages.

I also compensate my numbers, because the SuperCharger network is probably granularly reporting to the tune of every hour, but outages persist in a distribution from 1 hour to 30 days. Accordingly, I probably missed, ROUGHLY another 10% that came and went because of a brief power outage that happened between my observations.

Best estimate is 362+18+36 (416) outages over 190 days for, on average, 355 SuperCharger sites (count of sites has risen from about 345 to 376 over this period).

355*190 = 67450 site-days during my period of observations

A typical site can go about 162 days without Reduced Service or Temporarily Closed shown to the car's Nav (assumes that Tesla does not conceal charger status at the remote ends of the continent).

Based on data collected in Houston, TX during Jan - mid-July 2017, for a given SuperCharger site, odds are:

44% an outage occurs during the year; and
0.12% that any given SuperCharger has an outage on the day you travel to it.​

A road-trip that takes you through 16 SuperChargers has this probability of an issue:

.9988^16 uptime = .981 uptime ... or 1.9% of ANY SuperCharger causing a difficulty.​

Given those odds, you could go for 10 years without seeing a problem like this -- truly an event that is as risky as having a road-side flat, except you still have options:

1) Find fuel on inbound leg, using alternative charging site(s)
2) Slow down ... identify hotels/restaurants, even grocery stores and gas stations that would tolerate your plugging in
3) Find fuel while using your buffer, after passing the SuperCharger
4) Waiting it out at the SuperCharger, depending on what prospects SeviceNA gives you on it being operational soon
5) Since many of the 'outages' were merely 'Reduced Service', just plan to be at the SuperCharger an extra hour, getting refueled
6) Bedding down for the night, assuming you were on last leg for the day
​

Many things could change over the next few years to change these resiliency statistics:

• change in ownership of the SuperCharger network (e.g. create a non-affiliated federation of auto-manufacturers)
• normal wear/tear on the cables
• updates to the SuperCharger design
• Rosie the Robot plugging the cable to your car, and giving it a quick feather dusting after every use;
• financial distress of Tesla
• AI taking over the world and showing who is boss by shutting down the entire SuperCharger network

Incidentally, anyone who wants to periodically get a sense of the actual problem sites needs to spend a few minutes (maybe put your readers on) staring at the Nav to spot the odd red pins that are marked thus:

⊘​

 

[MyJoule]

While I agree the Superchargers are amazingly reliable, I've personally experienced two outages while traveling, (both more than a year ago now!) however, neither was really Tesla's fault. One was due to a thunderstorm a few hours before I got there and the other was right after a station had been activated and there was a problem with the utility transformer. Both times, Tesla "helped" by reading verbatim from Plugshare as to where the nearest alternate charging option was. They did offer to pay for the RV park that was the only alternative on one of these outages.

As a result of those experiences, I tend to charge the car a little more at a Supercharger stop than I would have- just to have an additional buffer to the next Supercharger and perhaps an alternative charger if there is a problem. This does lengthen the trip time a little, but not overburdeningly.

It's very good though that now the status is reported on the nav screen, that makes it less worrisome knowing that a station is up or down before departing for it.

 

[Missile Toad]

OK, some math edits needed to the above. My math was a little off:

416 (outages)
------ ............... = ............... 0.617% daily defect rate
67,450 (site-days)
​

A typical site can go about 162 days without Reduced Service or Temporarily Closed shown to the car's Nav (assumes that Tesla does not conceal charger status at the remote ends of the continent).

Based on data collected in Houston, TX during Jan - mid-July 2017, for a given SuperCharger site, odds are:

117% an outage occurs during the year; and
0.617% that any given SuperCharger has an outage on the day you travel to it.​

A hypothetical road-trip that takes you through 16 SuperChargers has this probability of an issue:

.9938^16 = .905 uptime ... or 9.5% chance of ANY SuperCharger causing a difficulty.​

 

[ChadS]

9.5% chance on a 16-supercharger trip? Seems high. I have Supercharged about 300 times and have never had an issue.

Maybe there is some poor person in Florida that has an issue every week...

 

[ReddyLeaf]

Even though I haven't road tripped as much as Chad, that does seem high. I've never seen a power outage in maybe 100 SCs. However, I have been ICEd once, see lots of single stalls ICEd, been to two SCs that were full of Teslas, and had numerous low power issues in the heat of the summer. Are you extrapolating from a single SC in Houston? Even if trying to extrapolate from a single region, you will definitely have a data bias. My home power is exceptionally stable, maybe one power outage every few years (several power blips per year that cause the clocks to reset, but nothing lasting). However, I've experienced multiple power outages when visiting family on the wet side of WA where downed trees cause numerous problems. I would expect that most SCs are tied to fairly significant grid connections and hence would only go down if there was a significant problem.

 

[dhanson865]

There's only one supercharger in my home town metro area serving 1 million + people. There is a thread here on TMC about that one supercharger location being down or reduced rate for weeks or months at a time.

For whatever number of users go through my hometown on their route on I-40 or I-75 (two highly traveled interstates) the odds of them hitting an issue here are higher than it is for the entire network.

Everything is relative, but for sure the entire network isn't resilient. It's just areas with enough locations to allow overlap/skipping a charger that have that resiliency.