Some California Superchargers not providing maximum charging rates

[Merrill]

Perhaps there is a lifespan to these chargers versus just transient effects from recent use. The California chargers could be wearing out quicker than lightly used chargers elsewhere.

I am not sure what goes on to maintain a supercharger anyway. Once they are set up it would seem they would just need a bit of inspection on the cables/connectors. It's not like there are moving parts inside. Perhaps some filters in the ventilation that need cleaning/swapping and to make sure the fans are working? These are manly solid state devices, no?

I have seen some of the cable connectors missing part of the pin inside, the outer part of the pin is either worn or broke off. Parts of the plastic chipped, I was only getting 40kWh and moved but it was no different at another stall.

 

[wdolson]

The charging units inside the cabinet are liquid cooled. The fan exhausts the heat sapped away by the cooling loop. Please correct if I am mistaken but I'm quite certain of it.

There may be some parts that are liquid cooled now, but when the tech had the supercharger torn apart for maintenance at Manteca, I didn't see any equipment for liquid cooling. Up at the top there was what looked like a bunch of low power electronics, the wires looked like they were around 18 gauge. He did find a wire that had broken in that electronic bundle, which may have been from residual heat build up in the cabinet.

He was replacing the charging cable assembly on all the SpCs there.

Perhaps there is a lifespan to these chargers versus just transient effects from recent use. The California chargers could be wearing out quicker than lightly used chargers elsewhere.

I am not sure what goes on to maintain a supercharger anyway. Once they are set up it would seem they would just need a bit of inspection on the cables/connectors. It's not like there are moving parts inside. Perhaps some filters in the ventilation that need cleaning/swapping and to make sure the fans are working? These are manly solid state devices, no?

Power electronics and densely packed electronics need some kind of cooling. Power electronics can need a lot of cooling. On the project I'm working on right now, the system I have for testing looks like an old 1980s IBM PC. I think they started with an 80286 clone case (this project dates back to the late 1980s). On one end is a high output power supply that has a transformer that weighs about 40 pounds. The power supply has some high power rectifiers attached to a heat sink twice the size of the transformer. They have an 120V AC fan that blows on the heat sink and sounds like a diesel pickup truck. The rectifiers are only 1 cm square, but they produce enough heat to require a giant heat sink.

And this power supply is only about 1.5 KW. Superchargers can produce 120 KW. At those currents, just the electricity flowing through the cables is going to produce a lot of heat. I'm not sure how big the conductor is inside the cable. The cables themselves about about 1 inch in diameter, but the conductor inside is smaller than that, the insulation on the cable is probably pretty thick. The resistance of the cable is a product of the resistivity of the conductor and the diameter, but the power loss is I^2R, so whatever the resistance of the cable, it's multiplied by 300A squared. Copper is the best practical conductor we have and has the lowest resistivity, but there still is some resistance and with high currents, you get heating from the losses.

Ideally it would be great to use superconductors (completely zero resistance), but the best superconductors we have still need to be cooled to the temperature of liquid nitrogen to work. They aren't really practical for anything except very special applications.

 

[Tony8489]

This past weekend we had our first extended road trip since the supercharger slowdowns became widely observed.

Arrived 9AM 10/13 Harris Ranch with 34 rated miles: We read that 5AB were most reliable, so pulled into 5A even though 5B was occupied. Charge rate was ~72kW, so moved to unpaired 4B, which started up at 105kW so we went inside for breakfast. After ordering I went back out to check and the charge rate had dropped to 62kW just as I've read so many times here. As I got back to the front door, I saw people getting into the X at 5B so I went back and moved to 5A. 5A was just fine, starting at 110kW with gradual tapering, so when we were done with breakfast after an hour the car was at 245 rated miles and ready to go. We also noted that the slowed down 4B cable was hot to the touch when I moved the car after 10 minutes, much more so than the 5A cable after nearly an hour of charging.

Arrived 12:15PM 10/13 Dublin with 55 rated miles: We only needed a short charge, over half the chargers were in use so we were paired. Nonetheless the charge rate was a sluggish 34kW when we left with 128 rated miles, less than half full. We had an extended conversation with a service tech there, detailed below. The cable was hot here too.

Arrived 1:45PM 10/13 Napa with 61 rated miles: We left the car there and were picked up for a wine tasting. Car was fully charged at 284 rated miles when we returned. Only one other car was there.

Arrived 9:30PM 10/15 San Mateo with 18 rated miles: It had been raining most of the past 6 hours. We parked at 2B as the 2's were the only unpaired. Charging started at the normal 100+kW rate. With about 1/3 charge we noticed the telltale lower charging rate of 62kW range. Shortly thereafter the car in 3A left so I moved to 3B. The charge rate went back to 106kW and operated with normal tapering for the next 45 minutes. As at Harris I noticed the slow charge cable 2B being hot to the touch when removed and the faster 3B cable still cool when removed after a longer charging time.

Arrived 4:00PM 10/16 Harris Ranch with 17 rated miles: Only 3 cars were there. I plugged into unpaired 5A and it was all good again. We were there for dinner and shopping 1.5 hours and left with nearly full charge of 281 rated miles to get home nonstop.

As Burbank was not busy last night we charged from 49-255 rated miles there in an hour, which is about the normal rate.

The Dublin Service Center tech had plenty to say about the slow supercharging situation.
1) It is absolutely caused by heat. Hot weather is a factor but the most important reason is heavy and continuous use of the chargers.
2) Currently Dublin is often the second most heavily used charger in the world, as shown on a display screen in the office there. Local ownership in the East Bay was not that high in the early years of Model S but has exploded over the past year. There is heavy local usage, frequent lineups and occasional altercations. They are sending out warnings to owners who leave their cars there well past the time needed to charge.
3) The situation above is causing overheating of Dublin chargers, the slowdowns after 5-10 minutes and even some cases where the cable handles are so hot the owners come into the Service Center to get a tech with gloves to help them unplug.
4) Tesla Corporate "absolutely knows about the problem." The water cooled cables at Mountain View are an attempted resolution.

I find the Dublin tech's comments credible. I don't think it was coincidence that at both Harris Ranch and San Mateo the slow charging cables were hot to the touch while the correctly functioning ones were cooler even though they had been plugged into my car for much longer. The silence of Tesla Corporate on this issue is consistent with the track record of being close mouthed about problems, even when they are working diligently to fix them.

 

[jeffro01]

Interesting... One comment though, it's really not cool to park your car at an SC and then leave it there for an extended period of time unoccupied...

Jeff

 

[Tony8489]

Interesting... One comment though, it's really not cool to park your car at an SC and then leave it there for an extended period of time unoccupied...

The only time we did that was the Napa wine tasting. It was about an hour and a half and we saw only one other car there both at arrival and departure. We drove nearly 200 miles within Napa and Sonoma over the next 2 days so really needed that charge at the beginning of our time in the area.

On the perhaps once a month occasions at Burbank I always monitor SOC on my phone and pick up the car between 80-90%. And due to Burbank's reputation these occasions are late at night.

 

[MP3Mike]

4) Tesla Corporate "absolutely knows about the problem." The water cooled cables at Mountain View are an attempted resolution.

Nope the water cooled cables were an attempt at making them more flexible and being able to up the charge current. In any case weren't they removed before this whole reduced charging rate thing became big.

 

[Tony8489]

I stand corrected on the reason the Mountain View water cooled cables were installed. Perhaps the Dublin tech assumed more effective cooling would be a side benefit.

 

[livingthedream]

I was just reading about the reduced charging symptoms described here, shorty before charging at the Roseville Galleria where I've never had a problem. I plugged in, went across the street to grab a beverage, and walking back noticed on my app that I had only gained 6% in 15 minutes. As I reach the car, there's a guy in the next spot saying his car wouldn't charge at all. My charge rate was only ~30kw. I decided to unplug, blow out the connector (it was raining, just in case it got wet) and plugged back in. Charging resumed, now in the ~90kw range. While I sat there waiting, at least 3 others tried the spot next to me (1B) to no avail even though mine was back to normal. Did the rain have anything to do with my initial slow charge rate or was that coincidence? Has anyone else tried re-plugging when having this issue, and did it do any good?

 

[NOLA_Mike]

Has anyone else tried re-plugging when having this issue, and did it do any good?

What I have found is that if you are monitoring and notice right when it drops down and try unplugging and plugging back in the same charger it usually has little effect (it will generally resume at the reduced rate). If you "go to grab a beverage" (or whatever other activity) and don't notice that it dropped down and that by the time you do notice 10 or 15 mins have gone by at the reduced rate then unplugging and plugging back in will generally get you a faster rate for at least some time.

 

[ecarfan]

I find the Dublin tech's comments credible. I don't think it was coincidence that at both Harris Ranch and San Mateo the slow charging cables were hot to the touch while the correctly functioning ones were cooler even though they had been plugged into my car for much longer. The silence of Tesla Corporate on this issue is consistent with the track record of being close mouthed about problems, even when they are working diligently to fix them.

Tony, thanks for your very thorough report! I am doing a San Mateo to Tustin (Orange County CA) roundtrip late next week and will try to document my charging experience.

 

[ShotgunF15E]

Not sure how many times we need to post this, but Tesla is well aware of the hardware issue and will tell you if you call that it's a hardware issue.

The fact is, they're not fixing it, or at least not fixing it with any sense of urgency.

Better bring a Snickers bar......

 

[apacheguy]

I've never been told that it's a hardware issue. Explanations given have ranged from battery thermals to utility power fluctuations but never once have they admitted to me that it is the cabinets or the cabling.

 

[FlatSix911]

The Dublin Service Center tech had plenty to say about the slow supercharging situation.
1) It is absolutely caused by heat. Hot weather is a factor but the most important reason is heavy and continuous use of the chargers.
2) Currently Dublin is often the second most heavily used charger in the world, as shown on a display screen in the office there. Local ownership in the East Bay was not that high in the early years of Model S but has exploded over the past year. There is heavy local usage, frequent lineups and occasional altercations. They are sending out warnings to owners who leave their cars there well past the time needed to charge.
3) The situation above is causing overheating of Dublin chargers, the slowdowns after 5-10 minutes and even some cases where the cable handles are so hot the owners come into the Service Center to get a tech with gloves to help them unplug.
4) Tesla Corporate "absolutely knows about the problem." The water cooled cables at Mountain View are an attempted resolution.

Good information from the Tesla Tech, however the Mt. View water cooled cables have been replaced with the old version.
I suspect the Mt. View location is the most heavily used SC charger and they were not able to solve the heat issue ...

 

[whttiger25]

1) It is absolutely caused by heat. Hot weather is a factor but the most important reason is heavy and continuous use of the chargers.

I've had slow charging problems at locations like Harris Ranch, Atascadero, Roseville Galleria, Fresno, Gilroy, Tejon Ranch, and Vacaville where I was unpaired and the location mostly deserted (from me being the only one there to it being maybe 30-50% full, but certainly no continuous charging or waiting lines). So I'm not sure how to reconcile those experiences with heat and continuous use certainly being a factor.

I've also had problems where continuous use was occurring at Gilroy (a separate time), Fremont, Burbank, San Mateo, Atascadero (separate time), Dublin, Vacaville (separate time).

In general weather has been variable from cool to hot throughout these experiences.

I'm wondering if these Tesla techs really have any clue?

 

[TexasEV]

I've had slow charging problems at locations like Harris Ranch, Atascadero, Roseville Galleria, Fresno, Gilroy, Tejon Ranch, and Vacaville where I was unpaired and the location mostly deserted (from me being the only one there to it being maybe 30-50% full, but certainly no continuous charging or waiting lines). So I'm not sure how to reconcile those experiences with heat and continuous use certainly being a factor.

I've also had problems where continuous use was occurring at Gilroy (a separate time), Fremont, Burbank, San Mateo, Atascadero (separate time), Dublin, Vacaville (separate time).

In general weather has been variable from cool to hot throughout these experiences.

I'm wondering if these Tesla techs really have any clue?

I think he's referring to internal heat, not the external temperature.

 

[Tony8489]

I think he's referring to internal heat, not the external temperature.

That was the way I interpreted it. Perhaps chargers with heavy use degrade in some way and become more prone to overheating. I don't think it's coincidence that the 3 slow chargers I encountered had noticeably hotter handles when I unplugged them than other chargers which were charging at the normal rate.

 

[gaswalla]

will be interesting to monitor charge rates at Buena Park. No issue of degradation,wear, and tear with new superchargers.

 

[whttiger25]

I think he's referring to internal heat, not the external temperature.

I get it which is why I brought up all my experiences of slow charging at locations that were empty or nearly empty - why would heat build up if I was the only one there?

 

[TexasEV]

I get it which is why I brought up all my experiences of slow charging at locations that were empty or nearly empty - why would heat build up if I was the only one there?

Because a component has degraded from heavy use, even if wasn't used immediately before you charged?

 

[whttiger25]

Because a component has degraded from heavy use, even if wasn't used immediately before you charged?

Fine you win, but what's becoming clear is that Tesla is in over their heads and not capable of maintaining their infrastructure such that it keeps up with the rapid growth of their company and fleet