-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
New Model X charging limit to 32A
- Thread starter saz25
- Start date
Thoroughly confused by all this I called Tesla and was told by them that the maximum recommended breaker for the wall charger is 60 Amps (unless one is driving multiple chargers from the same circuit). I just took delivery on my X 100D and the charging rate control can be set (with no connector in the charge port) as high as 72 amps (90A breaker), When I asked what the significance of that was he asked me to hold, went off line, came back and said he didn't know but everything he could access said to use a 60 A breaker (which would give a maximum charge rate of 48 A). Tesla's web page also indicates a 60 A breaker for the X 100D.
So there is an apparent conflict here. How do we find out what the real story is? Experiment! Don't try this as home kids.Hooking up the WC to the panel with some SJOOW tied to a 50 A breaker and setting the dial in the WC to 8 (50A breaker) the control allows charging rates up to 40 A (80% of 50) as it should and the charging indicator reads, e.g. 36A/40A. Setting the dial in the WC to C (90 A breaker) the control in the vehicle allows any setting up to 72A (80% of 90), and the charging indicator reads, e.g. 72A/72A. An ammeter on the WC feed confirms that it is, indeed, drawing 72A.
So there it is. The X sitting in my garage has a 17.28 kW (72 A) charger in it. I cannot, of course, speculate on what is in the current production of S or 3 or what might be in the X with the smaller battery or whether any option I bought has an influence on the installed charger capability (I won't say size as there seems to be speculation that they are all the same size with some of the capability crippled by firmware in some models).
So then why is Tesla publicizing a 60 A breaker for the X when it can handle the current from a 90 A breaker? Perhaps an abundance of caution as they did with limiting their 14 - 50 P adapter (which can handle 40 A) to 32 A.
If there is anything to be taken away here I suppose it should be that one should pull #4 (THHN or equivalent) for a wall charger installation. That will handle a 90 A breaker if you want to get the full 72A or, of course, a 60 A breaker if you want to follow Tesla's recommendation on the assumption that slower charging is easier on the battery. Of course if you have a 90 A breaker you can always dial down to 48 A on the touchscreen if you want lower charging rates for day to day use but would like to be able to boost the rate somewhat for a particular occasion.
So there is an apparent conflict here. How do we find out what the real story is? Experiment! Don't try this as home kids.Hooking up the WC to the panel with some SJOOW tied to a 50 A breaker and setting the dial in the WC to 8 (50A breaker) the control allows charging rates up to 40 A (80% of 50) as it should and the charging indicator reads, e.g. 36A/40A. Setting the dial in the WC to C (90 A breaker) the control in the vehicle allows any setting up to 72A (80% of 90), and the charging indicator reads, e.g. 72A/72A. An ammeter on the WC feed confirms that it is, indeed, drawing 72A.
So there it is. The X sitting in my garage has a 17.28 kW (72 A) charger in it. I cannot, of course, speculate on what is in the current production of S or 3 or what might be in the X with the smaller battery or whether any option I bought has an influence on the installed charger capability (I won't say size as there seems to be speculation that they are all the same size with some of the capability crippled by firmware in some models).
So then why is Tesla publicizing a 60 A breaker for the X when it can handle the current from a 90 A breaker? Perhaps an abundance of caution as they did with limiting their 14 - 50 P adapter (which can handle 40 A) to 32 A.
If there is anything to be taken away here I suppose it should be that one should pull #4 (THHN or equivalent) for a wall charger installation. That will handle a 90 A breaker if you want to get the full 72A or, of course, a 60 A breaker if you want to follow Tesla's recommendation on the assumption that slower charging is easier on the battery. Of course if you have a 90 A breaker you can always dial down to 48 A on the touchscreen if you want lower charging rates for day to day use but would like to be able to boost the rate somewhat for a particular occasion.
Last edited:
The reason for your confusion is the Tesla rep is giving info based on what’s being built currently, which is cars with 48A chargers. He doesn’t know that Tesla built cars with 72A chargers until very recently. He likely wasn’t even working at Tesla then. Understand that the average Tesla rep knows less than many owners who have had the car for a while or who follow the relevant threads on TMC.
If you have a 48A charger, Tesla would recommend a 60A circuit. Any more would none overkill unless you want to charge two cars simultaneously. If your car has a 72A charger and want to take full advantage of it, install a 90A or 100A circuit.
If you have a 48A charger, Tesla would recommend a 60A circuit. Any more would none overkill unless you want to charge two cars simultaneously. If your car has a 72A charger and want to take full advantage of it, install a 90A or 100A circuit.
My car was built in late 2018. It has a 72 Amp charger.
Apparently they still do as I have one that I assume was built in the last couple of months or so. Can one tell when it actually rolled off the line from the VIN.
How about other people with X's on here? Un-plug your charger and see what the charge setting control shows as the maximum.
Why doesn't that surprise me?
I wouldn't advise people to install a 100 A circuit as that requires pulling #3 through 1" EMT which has got to be a real joy (I suppose you could do the long part of the pull through a larger conduit and transition down to 1" or use a reducing bushing, if such things exist for EMT, for the last bit) and it doesn't buy you anything as the charger in my car is limited to 72 A for which a 90 Amp breaker and #4 are adequate.
Unlike traditional auto companies, “built in the last couple of months or so” is ancient history for Tesla. The cars are continually changed (Tesla would say continuously improved, but I don’t consider going from 72A charger to 48A charger in the 100 kWh cars an improvement).
You can see the month of manufacture on the door jamb sticker.
I'm feeling pretty stupid right now but I can't find anything on the driver's door jamb except the tire inflation sticker. Where should this sticker be relative to that? I've checked driver and passenger side front doors with no luck.
I'm happy. I've got a 72 amp machine but I'd like to get to the bottom of this for the sake of others. The car is a 2018 model and as I gather the X's are selling pretty well (through Q2 they were selling about as many X's as S's) I'm assuming that this one wasn't made last January but I suppose it could have been.
This keeps getting more interesting though. I'm now hooked up to a 50 A breaker and I can ask for 40 amps which I get so with a line voltage of 238 the power supply is pulling 9.52 kW, right? Well no. It is actually pulling 9.52 kVA but the real power is only 7 kW. IOW the actual charging current is only 30 Amps (power factor 0.74)! The thing is pulling 6.4 kVAR too. Where is that going? I guess there has got to be a boost mode DC/DC converter right behind a rectifier in there and that, of course, would involve a fat inductor but I'm surprised the power factor is that low.
I'm happy. I've got a 72 amp machine but I'd like to get to the bottom of this for the sake of others. The car is a 2018 model and as I gather the X's are selling pretty well (through Q2 they were selling about as many X's as S's) I'm assuming that this one wasn't made last January but I suppose it could have been.
This keeps getting more interesting though. I'm now hooked up to a 50 A breaker and I can ask for 40 amps which I get so with a line voltage of 238 the power supply is pulling 9.52 kW, right? Well no. It is actually pulling 9.52 kVA but the real power is only 7 kW. IOW the actual charging current is only 30 Amps (power factor 0.74)! The thing is pulling 6.4 kVAR too. Where is that going? I guess there has got to be a boost mode DC/DC converter right behind a rectifier in there and that, of course, would involve a fat inductor but I'm surprised the power factor is that low.
It's a very recent change. Like mid-Nov. My parents just picked up an inventory S 100D that was built in Nov. It has the 72A charger. Any S or X coming off the line now does not. They only have a 48A. Again, the change only happened a few weeks ago.
If you have a 100 that was built pre-mid-Nov, it has a 72A. After mid-Nov, 48A. You cannot tell manufacture date (or order) by the VIN number; Tesla assigns VIN's in somewhat random order (not sequentially).
If it’s like my Model 3, the month and year of manufacture are on the upper left corner of the white tire sticker. Mine says “03/18” (without indicating that means month and year of manufacture). Speaking of which, your car isn’t really a “2018 model” as Tesla doesn’t do model years. It may have to be called that for registration and insurance purposes but if Tesla had its way it wouldn’t be called that, as they continuously change the cars and calling it a 2018 model implies it’s similar to others built in 2018 when that may not be the case.
It is entirely possible that this car was indeed built prior to mid November. It was an inventory vehicle and I'm really glad I decided to take it as I'm getting the full $7500 from Uncle Sam and an extra 24 Amps from Elon.
The only numbers on the tire sticker are 137972. If that represents a date it must be from the Aztec calendar.
The only numbers on the tire sticker are 137972. If that represents a date it must be from the Aztec calendar.
That won't help me much. My 'window' sticker was not attached to the car but rather handed to me by the delivery guy. In the excitement I just set it down somewhere and in my house you don't do that. If it's there, whatever it is (including letters from the IRS) it's in the garbage within 10 minutes.
That is bad. When you trade/sell the car they may want to see it since there car and equipment options change all the time.
Well not so bad after all as I found it in the trunk. Which is great except that I don't think it is going to help that much in determining what is currently going on with the OBC. The vehicle was manufactured in December, that is, after Thanksgiving so perhaps the cutoff for the 72 Amp OCG was later than Thanksgiving. What is really interesting, though, is the sticker lists "High Amperage Charger Upgrade" as INCLUDED. The significance of that to this discussion I do not know. It suggests that the high amperage (72 amp) charger is still available as an upgrade and I guess my advice to prospective buyers would be to mention this and see if they can get it. OTOH it also suggests that they had a bunch of high amperage chargers left over from a previous production run and are going to keep installing them until they run out of them. And, of course, we are all well aware that a 72 Amp charger can easily be crippled in software such that it will produce only 48 A easily changed to produce the full 72 A if the "upgrade" is purchased at a later date.
They can't use up all of the 72A chargers on new production; they need spares to replace failed modules in customer cars.
gnuarm
Model X 100 with 72 amp chargers
Where are you measuring these numbers? Do you understand the difference between them?
VA (volt-amps) is just the product of the voltage and amperage. It is called "apparent" power.
W (watts) is the real power and is the product of volts and amps times a factor that adjusts for the difference in phase of the two (assuming they are both still sine waves).
I've never heard of VAR before, but it is the "reactive" power. In AC circuits the actual or "real" power is the power that is actually transferred from the line to the load. The reactive power is power that flows to the load during part of the cycle and back from the load to the line during another part of the cycles... again, assuming everything is sine waves.
A number called the power factor indicates how different your true power is from the apparent power regardless of whether the current and voltage are sine waves or not. When the power factor is not very close to 1 the power company doesn't like it. The reactive power isn't transferred to the load, but does result in higher currents than should be needed and so losses in transmission are higher. I know industrial customers can be charged higher rates for this.
In power supplies the power factor can vary a lot from unity if not corrected for because the current can be more spiky and not as much like a sine wave. I am surprised this is happening with the Tesla chargers. I'm not a power supply designer so I don't know all the regulations, but I thought larger power devices did have requirements to meet in this regard.
To answer your question, the reactive power is not going anywhere really. If the voltage and current are pure sine waves, excess power flows into the load (usually a motor) during part of the cycle and back into the line during the rest of the cycle. The power meter compensates for this only measuring true power. In the case of power converters the current will be high during part of the cycle and very low during the rest of the cycle and while there is no power flow back to the line at any time, the unevenness of the power flow is reflected in the power factor and considered reactive power as if it were flowing back and forth. It also cost the power company because of higher losses in transmission.
You gave me a bad turn here fot a minute because when I saw the question I couldn't remember! That happens when you get to be my age. But then it came back to me. I got them by comparing the power drawn by the panel to which WC was connected to the VA drawn by that panel. [/QUOTE]
Yes, in 50 years of electrical engineering I have gained a passing acquaintance with some of these terms
Not quite but sort of.
You have never heard of Vars before but you are ready to tell us what they are?
Vars are the imaginary part of the integral of the product of voltage and the complex conjugate of the current divided by the time over which the integral was computed. Voltage and current are both complex, usually periodic functions of time here. The real part of this normalized integral is the actual power delivered to the load i.e. watts or joules per second delivered to the load. Vars can be though to as joules per second stored by a component and subsequently restored to the system - sort of the power that would be delivered by an imaginary current. There several reasons to track vars the pertinent one here being that the reactive current (vars divided by voltage) is a real current that warms conductors.
Power factor is the ratio of the magnitude of the imaginary part of the integral to its magnitude, If the voltage and current waveforms are both sinusoids of a single frequency then it is the cosine of the phase angle between them and represents the fraction of the product of rms voltage and rms current that is delivered to the load as real power.
You seem to have some familiarity with some of these concepts but this isn't EE school. What is of interest here is the properties of the OBC. I took some measurements from which I conclude that the OBC was an inductive load. The problem is that the measurements I took were invalid as there was a problem with the CT (current transformer) measuring one of the phases to the panel. I corrected this and then took the further step of installing a CT directly on the branch feeding the WC so I could get a direct pf measurement. When the load is small (towards end of charge0 the pf goes down to 0.92 - 0.95 but when the load is 40 amps it is essentially 1.
Clearly these are switching supplies. They can be pf corrected by intelligent gating algorithms. I want to look at the current waveform but I think I must have left my oscilloscope at out summer house.
I was surprised that the power factor I calculated was as low as it was but pf's of 0.8 are certainly not unusual. But as it turns out the true pf for these supplies is 0.9 - 1.0, higher when it counts at fuller load.
gnuarm
Model X 100 with 72 amp chargers
Well, that's a few years longer than myself. I spent a few years as a biochemist first, due to a bad teacher in high school.
How did you measure the power and the VA? I assume you can get the power from the car. Did you measure the volts and amps directly with a meter? When I put in a HPWC I plan to provide some loops in strategic locations so I can measure the current. I seem to recall there is a way to communicate with the HPWC to get info from it, but I don't recall what that is. Does it have a wifi link???
Please clarify for me.
There are lots of terms I've never heard of in electronics but I know what the concept is. I'm not a power engineer, but the only part missing was the reactive portion.
I would have explained the full picture to you, but I didn't know you understood complex numbers.
Yes, I think I mentioned that. For this discussion that is the only important aspect of the reactive power.
Ok, so what is OBC??? In case you haven't noticed about the only abbreviation I bother using is HPWC. I deliberately try not to use abbreviations as abbreviations are a great way to not communicate with most people.
Yes, that is why I was discussing this with you. It would surprise me greatly if the numbers you recorded turn out to be both accurate and typical.
At lighter loads no one really cares. But when the unit is drawing many kW the power company won't like it much. Do you know what the regulations are for a residence? I know businesses have restrictions and get whacked with penalties if their power factor is too far out of line.