Quite a difference between 120 and 240 volt charging.

[scaesare]

I suspect those 120V mph numbers for the Model 3 are understated.

A Gen 1 Volt charges at nearly 4mph on 120V 12A and the Model 3 is ~24% more efficient that the Gen 1 Volt. So unless there's something weird with Tesla's charging systems, a Model 3 charging at 120V 12A should be closer to 5mph than 3mph.

I suspect it will make 5 as well.

If voltage doesn't sag, I actually now[1] get ~4 from my model S 85. Did it last night as a matter of fact. Right at 12V/12A under load and was pegged at 4MPH charging.


[1] This may indicate recent improvements in low-power mode on the car. While I've charged on 120V circuits previously, I'd ususally get more like 3.5 MPH, which the car would round down to 3 on the display. But then again most of those times the voltage also sags a bit. Last night was the first time I've used 120V at home (where my unloaded circuit voltage is about 122V) in a while, and I saw 4MPH on the display.

 

[mongo]

With my 3/31/16 ordered M3 likely to arrive before May, i am ready to start preparing for charging at home, where I should have no problem with adding a 240V 50A circuit. At my commercial building, where I have a 68KW solar array which provides considerably more power than is currently consumed, I am wondering if I can benefit by using the DC power from the solar array before it goes to the inverters. Any thoughts?

Tesla charging is AC only. For this to work, you would need a current controlled (based on SOC) DC source at the pack charge voltage (also varying).

 

[scaesare]

With my 3/31/16 ordered M3 likely to arrive before May, i am ready to start preparing for charging at home, where I should have no problem with adding a 240V 50A circuit. At my commercial building, where I have a 68KW solar array which provides considerably more power than is currently consumed, I am wondering if I can benefit by using the DC power from the solar array before it goes to the inverters. Any thoughts?

Currently no "easy" way to get DC in to the car from solar.

One could ostensibly source a DC-powered Chademo charger to install (or build one yourself), but I don't know of any...

 

[ölbrenner]

You can't linearly extrapolate...

Until I get my Model 3 and can test the actual charge rates at different currents, I am going to stick with Tesla's published average charge rates (which show a very linear relationship, i.e. double the amps = double the mph charge rate).

 

[Lasttoy]

Home charging comes in 2 ways. It depends on home service. 100 amp or 200 amp. My old house only had 100, so I could only install 50 amp breaker. You need a double open slot in breaker box.
I don't count using 110v wall outlet, that takes a week to charge 250 miles.
I have dual chargers , that require 100 amp breaker to make them kick in. There is a Hilton near me that has 100 amp destination stop that charges really fast with my dual chargers. It's nice to see them really kick it up a notch not to be a super charger.

 

[scaesare]

I don't count using 110v wall outlet, that takes a week to charge 250 miles.

I suspect that was intentional hyperbole on your part... but for the sake of accuracy it's more like about 3 days for a 120V/15A outlet and a little over 2 days for a 20A outlet. Model 3 will likely gain range slightly faster.

 

[scaesare]

Until I get my Model 3 and can test the actual charge rates at different currents, I am going to stick with Tesla's published average charge rates (which show a very linear relationship, i.e. double the amps = double the mph charge rate).

Does it?:

 

[mongo]

Until I get my Model 3 and can test the actual charge rates at different currents, I am going to stick with Tesla's published average charge rates (which show a very linear relationship, i.e. double the amps = double the mph charge rate).

Are you refering to this page?

Not much granularity on the 120V table (12 vs 16 A, 3 vs 4 MPH). Note that based on those numbers, 4 extra Amps (33%) increases the X charge rate by 50%.

@scaesare
The 240 V table is showing something interesting. Either the base load of the 3 is 0, or Tesla is hedging their numbers by using a straight Wh per mile rate for the 3 only. Based on the new integrated pack/ charger/ 12V supply, the 3 could indeed have much lower fixed usage when charging (when not heating the pack). However, this also would require zero cooling power, or a straight linear relationship between cooling and charging.

Comparing the 240V 15A to 30A ((24-12)×240=2,880kW)

S: 7 to 17 MPH, 10 extra miles, 288 Wh per mile, 720 W base load
X: 5 to 14 MPH, 9 extra miles, 320 Wh per mile, 1,600 Wh base load
3: 11 to 22 MPH, 11 extra miles, 262 Wh per mile, 0 base load.
The rate numbers hold up well against the HPWC table also.

Backing these usage numbers into the outlet table again.
(240-120)@12 = 1,440 W
Table vs calculated
S: increase of 4 compared to 5 (table is lower)
X: increase of 3 compared to 4.5
3: increase of 8 compared to 5.5 (table is higher)

So from this limited data, the 3 takes a hit on 120V charging. Or the numbers are somewhat off and 120V looks worse than it is.

It shall be interesting see what reality has to say.

 

[ölbrenner]

Are you refering to this page?

Not much granularity on the 120V table (12 vs 16 A, 3 vs 4 MPH). Note that based on those numbers, 4 extra Amps (33%) increases the X charge rate by 50%.

Yes, and sticking to M3 not X discussion::

There's enough 120V granularity, and more than enough 240V granularity, to clearly show that a Model 3 [email protected] mph charge rate will in no way be close to the [email protected] mph charge rate as claimed by scaesare (which is where this whole sub-discussion started).

 

[ölbrenner]

Does it?:

View attachment 273255

X and S charts are not pertinent. Look at the Model 3 chart:
[email protected] = 11mph charge rate
[email protected] = 22mph charge rate

Double the amps = double the mph charge rate

 

[Vic4Model3]

Something else to consider is useful lifetime of the coolant circulation pump and how this pump is affected by run time.

Assuming the coolant pump is always running while charging the battery, like on models S and X, then charging at 240 Vac @ 24 amps will shorten the coolant pump run time by a factor of 4, when compared to charging at 120 Vac @ 12 amps.

 

[mongo]

Yes, and sticking to M3 not X discussion::

There's enough 120V granularity, and more than enough 240V granularity, to clearly show that a Model 3 [email protected] mph charge rate will in no way be close to the [email protected] mph charge rate as claimed by scaesare (which is where this whole sub-discussion started).

The X observation was to illustrate what should happen with a base load. If the 3 has proportionate conditioning loads, and keeps the rest of the systems asleep, then it all can stay linear.

Low single digit charges rates leave a lot of room for differences based on rounding style. If rounding, the table's 120V 12A vs 16 A values of 3 to 4 can be 2.5 to 4.49 (80% increase) or 3.49 to 3.5 (0% increase). If truncating, 3 to 4.99 (66%) or 3.99 to 4 (0%). That's why I say there is insufficient granularity to draw conclusions.

The 120 numbers are very strange if there is no base load (and strange in general). The 240V numbers imply 260 Wh/mile, 120V nunbers imply 480 Wh/mile. A 85% increase in power per mile seems very unreasonable for any modern power converter. Even adding a boost transformer to generate the 240V would only be a 5% efficency hit.

 

[mongo]

Something else to consider is useful lifetime of the coolant circulation pump and how this pump is affected by run time.

Assuming the coolant pump is always running while charging the battery, like on models S and X, then charging at 240 Vac @ 24 amps will shorten the coolant pump run time by a factor of 4, when compared to charging at 120 Vac @ 12 amps.

True, but if it is a variable speed pump, the effect is lessened. Also, at a low charge rate, the natural heat loss may reduce the pump operation requirements (only 1/4 of the heat to reject per unit time). Interesting to think about how the pump will see wildly different usage based on climate, type of driving, and type of charging...

 

[TexasEV]

Home charging comes in 2 ways. It depends on home service. 100 amp or 200 amp. My old house only had 100, so I could only install 50 amp breaker. You need a double open slot in breaker box.
I don't count using 110v wall outlet, that takes a week to charge 250 miles.
I have dual chargers , that require 100 amp breaker to make them kick in. There is a Hilton near me that has 100 amp destination stop that charges really fast with my dual chargers. It's nice to see them really kick it up a notch not to be a super charger.

Oversimplified to the point of being useless, if not misleading. Home charging does not come only 2 ways, and neither does home electrical service. There are many other possibilities besides 100 and 200A service. We have 225A, for example. Other houses have 150A. How much you can dedicate to EV charging depends on a load calculation, not what breaker you have room for. Your dual chargers in an early Model S (which aren’t available for current models, so please don’t confuse new or prospective owners with that) would start being used with any charging above 40A, meaning any circuit greater than 50A. It doesn’t require a 100A circuit.

 

[scaesare]

Are you refering to this page?

Not much granularity on the 120V table (12 vs 16 A, 3 vs 4 MPH). Note that based on those numbers, 4 extra Amps (33%) increases the X charge rate by 50%.

@scaesare
The 240 V table is showing something interesting. Either the base load of the 3 is 0, or Tesla is hedging their numbers by using a straight Wh per mile rate for the 3 only. Based on the new integrated pack/ charger/ 12V supply, the 3 could indeed have much lower fixed usage when charging (when not heating the pack). However, this also would require zero cooling power, or a straight linear relationship between cooling and charging.

Comparing the 240V 15A to 30A ((24-12)×240=2,880kW)

S: 7 to 17 MPH, 10 extra miles, 288 Wh per mile, 720 W base load
X: 5 to 14 MPH, 9 extra miles, 320 Wh per mile, 1,600 Wh base load
3: 11 to 22 MPH, 11 extra miles, 262 Wh per mile, 0 base load.
The rate numbers hold up well against the HPWC table also.

Backing these usage numbers into the outlet table again.
(240-120)@12 = 1,440 W
Table vs calculated
S: increase of 4 compared to 5 (table is lower)
X: increase of 3 compared to 4.5
3: increase of 8 compared to 5.5 (table is higher)

So from this limited data, the 3 takes a hit on 120V charging. Or the numbers are somewhat off and 120V looks worse than it is.

It shall be interesting see what reality has to say.

I was demonstrating that the relationship is not linear. Doubling the current at a given voltage doesn't simply double the charge rate. This appears to account for the static power draw/base load.

The 3 data is interesting... I do wonder if it either has a system that's capable of very low power that simply is rounded in to the integers they provide, or they are ignoring it in that table.

 

[scaesare]

The X observation was to illustrate what should happen with a base load. If the 3 has proportionate conditioning loads, and keeps the rest of the systems asleep, then it all can stay linear.

Low single digit charges rates leave a lot of room for differences based on rounding style. If rounding, the table's 120V 12A vs 16 A values of 3 to 4 can be 2.5 to 4.49 (80% increase) or 3.49 to 3.5 (0% increase). If truncating, 3 to 4.99 (66%) or 3.99 to 4 (0%). That's why I say there is insufficient granularity to draw conclusions.

The 120 numbers are very strange if there is no base load (and strange in general). The 240V numbers imply 260 Wh/mile, 120V nunbers imply 480 Wh/mile. A 85% increase in power per mile seems very unreasonable for any modern power converter. Even adding a boost transformer to generate the 240V would only be a 5% efficency hit.

And to further this, there's definitely some rounding/generalization going on:

- The 3 and the S show the 0% difference on a 120V/15A circuit

- There is nearly a 25% difference on on a 240V/50A circuit

- Clearly there is rounding going on as you describe. Here's my app right now as I'm plugged in to a 120V/15A circuit showing a 4MPH charge rate:

- Yet here's the actual power reported with an order of magnitude more precision @ 3.7MPH:

- This also shows 1KW of charger power, when the math figures to 1.4KW. So as you illustrate @mongo, the whole numbers are clearly approximations.

That having been said, the Model 3 table is indeed interesting.

 

[FlatSix911]

What you are saying about electrical overhead is correct and that is why the 240 volts is so much more efficient.

On my model S the mobile connector is supposed to be able to do 40 amps, but I found the cord and handle would get pretty warm at that speed. I turned down the charging on the car to 30 amps when at home and have not had any problem since.

If the charging speed is a concern you can always buy the High Power Wall Charger (HPWC) and charge at 48 amps or 44 mph. See the details here.
Home charging installation

 

[KJD]

What is your point flatsix911 ???

Do you dispute the fact that the chart you just posted says that on a 60 amp breaker max output is 48 amps and on the model 3 it will gain 44 mph ?

 

[FlatSix911]

What is your point flatsix911 ???

Do you dispute the fact that the chart you just posted says that on a 60 amp breaker max output is 48 amps and on the model 3 it will gain 44 mph ?

Relax, No worries ... just posting the complete chart that you previously referenced.