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HPWC Update?

Does anyone know where Tesla stands with the breaker solution on the HPWC units?

Mine was updated by a ranger about a month ago. Together with the 5.8 update for the car, I'm able to set charging (permanently) at up to 80A. All is now well for me in the HPWC world.

The local service center installed the updated breakers recently in my HPWC. If you have a local service center - call them, otherwise call Ownership.

Same here. Updated about 2 months ago.

No breakers - the update is replacing the 100A fuses with 200A fuses. The SC will send someone out, or you can pick up the fuses and do it yourself.

I picked up the breakers from my local service center and installed them myself. It was easy and spared me the hassle of scheduling a ranger. The entire install took me all of about 8 minutes. The replacement breakers had the same ratings as the fuses already installed in my HPWC but I replaced them anyways, I figure if they burn out I will have spares.

I was shipped an updated HPWC without the breaker issue in mid August. This issue has been resolved for some time now.

I was told by service the breaker issue was only a couple units and has not been a recurrent problem so they are not swapping out units or breakers. Since then I have used 80 amp charging without issues on my 2013 unmodified hpc.


I have had problems charging at 80 amps on HPWC since firmware 5.8 update. It kicks down to 60 amps within moments of starting to charge and gives an error message about extension cord being used or faulty wiring. The HPWC has been working flawlessly since I got the car in September. Anyone else seizing this problem?

My HPWC has been charging at 80A just fine after the latest 5.8.4 update. I would suggest rebooting your center console (press brake, hold both scroll wheels on the steering wheel until the screen resets). You should be back to 80A, but while charging keep an eye on the charging screen and look at your voltage number. Is it bouncing around, low or high?


If you are getting that particular message I would have an electrican check out your house wiring, breaker box and outlet to make sure that you have adequate wiring and that all of the connections are intact and undamaged.

The message that your car created was was different if you had the old fuses that were in the old HPWC. It automatically lowered the setting to 60A and told you that it was lowering the amperage because of the HPWC. There was no message about extension cords or the like.

There never was a HPWC breaker issue that needed updating to my knowledge. Newer units that were send out since about last April or May had the new fuses. I had my fuses replaced back then since I had one of the very first HPWCs.

Interesting data guys. I have been in touch with the electrician that installed my HPWC and replaced the main panel at my house the same time. I will try rebooting and see what happens.


200 amp fuses? Seems dangerous on a 100 amp circuit.

I'm getting the same message "extension cord ...." and being dropped to 60 amps. Took the Fluke out and made measurements. The majority of the drop occurs at the service panel bus bar just below the meter. Didn't measure other side of meter. Not much drop from Service panel to 100 amp cutoff or car. Maybe 1 1/2 to 2 volts.
I have a 200 amp service but it is appears that the city isn't providing me with the ability to pull the needed current.
As one would expect with the service panel drop in voltage the wall outlets also drop accordingly.
I understand that there are taps on the Transformer to set voltage to the houses it feeds. Before the transformer the utility is supposed to adjust for added load and doesn't appear to be doing that.

The car measures the voltage at no load and with a load and uses that data to imply the line resistance.

A very long or undersized service feed could trigger the car's protection mode. Alternately, corroded connections could be causing excessive resistance at the meter, the panel, or the service connection. Ideally, voltage should be measured at the service connection before the meter to determine whether it is a power company issue or your wiring problem.


As an engineer I got that on the implied high resistance from the car. It's pretty smart how they ramp up the current slowly while checking the voltage. I am also assuming by doing that it may give the utility company the ability to provide for extended draw of a higher load. The transformer is no in my back yard I need to look at how many poles away.
I did get a new meter a couple of years ago and the service panel was replaced when I upgraded in 2008 from 100 amps to 200 amps. The city later ran new wire down from the pole to the house. No longer using the 3 separated wires but in a twisted mode now. I figured for common mode rejection.
Not sure how to measure on roof. I need to look but I think they have the connections covered.
The first day I charged my voltage dropped down to 223 and car switched to 60 amps. I was able to at that time increment the amps at car in 1 amp increments. Instead of a linear slope at 60 amps it was 229 and around 65 amps 223. It was as if the service had no more juice to provide and voltage plummeted.

The power company does not have any adjustable setting at your service transformer so it doesn't care what load you draw. The voltage changing taps are at the local substation. Even if the transformer is several poles away, the main line from pole to pole is design to service multiple homes, so it should be OK.

Since you said that you had your service upgraded a couple years ago, the most likely suspect is that your wiring has a resistive connection. It doesn't take much to cause trouble. Even a 0.1 ohm resistance at a single point will cause overheating, and it is too small of a resistance to measure with any handheld meter. A thermal scan should be able to see it. Either a lug has loosened or a connection has corroded.

The utility connections on the roof are usually insulated crimp lugs. The needle probes on a meter should be able to slip in next to the wire. However, from the above paragraph, I think we already know where to look.

One other thought, large loads (A/C or electric ovens) switching on at your or your neighbor's homes will cause a few volts of drop due to the transformer resistance, so that could aggravate any marginal condition.

@DonS Thanks for your inputs. I just checked the roof and there is a hard cover over the 3 wires coming in. I swear that the wire guage coming in doesn't look any larger than the 2 AWG that I am running for the HPWC, looking at it for about 10 feet away.
When I did the load calculations for the high current draws on the house to get the approval for the HPWC, I recorded the HPWC at 80 amps, The Air conditioning at 20 amps, and the oven at 40 amps. At that point we have 140 amps. The rest are recessed LED lights, TV's, TIVO and other low current devices. So we met the derating requirements for the 200 amp service.
I think at this stage I will call the city and see if I can speak to an engineer in the utility department of Anaheim. I can't read above the meter unless I open up the outside wall.
There was a post before about the substation taps not auto switching.

I read this article here from PGE

Although #2 would be undersized for a 200A service, the power company wires are in air, so they do not need temperature de-rating that is needed when in piping. That lets them run one or two sizes smaller than you would inside a building. Also, power companies usually use Al instead of Cu, so the loading is different there too.

Let's suppose for a moment it really is an undersized #2 service feed. A 100' run of #2 has a resistance 0.01563 ohms, so the voltage difference for the 80A HPWC ON/OFF is only 2.6V (1.3V on each leg). This is not enough to cause the trouble you are seeing. Once again, a loose or corroded connection is the most likely culprit. It might be up on the feed, but the screw lugs on the meter and panel are more probable.

Tap switching is related to changing load in a neighborhood such as when it gets warm and hundreds of homes run their A/C. Your single load is irrelevant. If it was power company related, the car charger would run fine at maximum current most of the time, but randomly drop back to the lower current.

The run is a couple of poles down so might be around 300 feet to the transformer. Still my eyes may be deceiving me on wire gauge.
I think your bet on a high resistance connection will turn out to be right.
Thanks for the info on the sub station tap switching.
I called the city Utilities and they were going to come out today but I just got my Tesla back from detailing with Opti Coat Pro and I wanted it around to be able to pull a load along with the AC and oven to show the guy.
I will call again Monday morning to get them out on Monday. Apparently they will come out the same day as the call.
When I get an answer to this problem I'll post to let you know if you are curious. Meantime I will charge at 40 amps overnight.

@DonS Update. Monday the Anaheim Utilities came out to look at the situation. Brought 2 big trucks with two guys. I explained the situation to one while the other had his binoculars and was walking down the street to look at the transformer. I would gauge that it's around 100 yards from the house. We then went into the backyard where they looked at the hookup on the poll and said it wasn't standard Anaheim connections and the wire must have been upgraded by a contractor. We went on roof where they hooked in a load but were having troubles making it work. They then put on a recorder and will monitor for a week, come back take the recorder and download the data. In the meantime at end of day charging the Tesla and it starts out at 80 amps and drops down to 60 shortly thereafter. Not even running the stove, only air. I got down of the 240 to 216 with 108 on the 120 outlets.

The Utility guy said he sees a problem with setup. I think I heard them talking when I was a little bit away and they seem to think the transformer ins't up to the load. I thought I heard a 100 amps, when I asked them one said they run at 6 or more times their rating? One talked about in the end possibly putting a transformer on the pole in my backyard.
At present the regulation under load is atrocious.

Thanks for the update. I forgot about the transformer itself. When I told the local utility that I had an EV, they calculated that my shared transformer was overloaded, and they would upgrade as needed. With the SmartMeters, they can really get accurate loading data. Homes today have more electrical appliances and many are larger than when the subdivision was built.

@DonS I'll let you know what comes next. I talked to Tesla today on this. One of their experts is going to call me next week to talk. I spoke with someone that had experience in this. It seems it's the responsibility of the Utility to provide a regulated voltage at rated current. So we will see. Tesla is going to look over the charge data. If the city balks then Tesla may be able to put together info also showing the problem. The do monitor voltage and current.
Got the house voltage down to 108 during charge today. Only big things running are charger that quickly defaulted to 60 amps and A/C, TV and a few LED lights.

Looks like the fuses went in my HPWC when charging at 80 amps. The other night about halfway through the charging cycle the HPWC died. No LEDs or anything. It's getting power. Tesla will be out tomorrow morning to fix it.

Curious what they find. The fuses shouldn't blow since the car is limiting the charge to 80 amps max.

@DonS Got a call the other day from the tech who came out to look at my problem with city power. They had looked at the data recorder on my power input and the city will be putting in a transformer on my pole in my back yard. Also they were sending an engineer out to look at how some of the work in the are was done. It seemed to me that the techs said some of the connections were not as the city wants.
Talked to Tesla and the charging logs show that the city power dropped each time I charged and the charger was fine.
I asked to speak to the engineer when he comes out but don't know if that will happen. Looking forward to getting good city power.

No problems charging at 80 amps. The HPWC was installed a year ago and I have not had any problems. Previous to the installation of the HPWC PG&E had installed a new pole mounted transformer on the circuit that I get my power from.

So it is sounding like your utility transformer is too far or overloaded, or a bit of each. Let us know if you get a definitive answer.

@DonS. I estimate the run at about 100 yards. When I was on the roof with them and the were hooking up the data recorder I got to see the exposed wire. I'm guessing 2/0.
I am suspicious that from the techs conversation that the transformer is underrated.
May be a number of weeks until they schedule work.

I thought I'd chime in, since I had been having all sorts of charging problems that ended up being due to insufficient voltage. I actually wrote some python code to monitor the charge every second and plot in excel. I was discussing with Tesla and wasn't making much progress.

I live in Southern California Edison territory, and a with bit of googling I figured out that they commit to delivering at least 114V on each leg of the circuit, not just 228V for the 240V circuit, and I was seeing voltages ~214V. So, I called SCE on a Sunday afternoon. They had someone at my house 30 minutes later, and he quickly concluded my voltage was too low, coming from a transformer too far away. He said he'd write an order to install a transformer on my pole, and re-feed a few of my neighbors as well, and that it would take a week or two. They showed up on Monday.

No more charging problems. I had assumed that SCE wouldn't do anything about my supply, and was ultimately amazed at how quickly they responded. I wished I had called them years earlier...

Wallowing in electrons, now? Or do you prefer positrons?

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