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Can we manually set the charging speed to a lower rate in a Tesla Wall Connector?

MikeHolliday

Member
May 9, 2020
377
275
Worthington, Ohio
Why 3/4 in. Knockout Threads???? On the Tesla Wall Connector you can drill up to a 1 3/8 in. hole on the bottom or back for rear entry...

From the manual page 16 - "NOTE: For 1 in. (27 mm) rear and bottom entry options, drill with 1-3/8 in (35 mm) step bit to prepare wirebox for fittings."
 
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thecavalry

Member
Aug 27, 2021
170
211
Utah
I found 4/3 MC locally. Holy crap it's huge. 1" actual diameter. The electrical shop didn't have the correct connectors. All of the metal boxes only have 3/4" knockouts. I need to find a connector that has a 3/4" threaded side that will accept 1" MC
Get a step bit and make a bigger hole, then use the correct size fitting for 1”.
 

MachAF

Member
Feb 3, 2020
32
19
CZI
I found 4/3 MC locally. Holy crap it's huge. 1" actual diameter. The electrical shop didn't have the correct connectors. All of the metal boxes only have 3/4" knockouts. I need to find a connector that has a 3/4" threaded side that will accept 1" MC
I've been waiting for this post!
 

MikeHolliday

Member
May 9, 2020
377
275
Worthington, Ohio
The calculations are not rounded, only the data on the chart was shown rounded to 2 decimal places. Not sure one would call rounding to 2 decimal places as flawed. Anyway here is a snap shot rounded to 5 decimal places instead of 2 decimal places if that makes better sense to you. Regardless the conclusions remain the same on the efficiency of charging at various Kwh rate as determined by the Circuit breaker current rating.


View attachment 711041
Here is what I came up with using Tesla's Published Charge Rate for the Model Y and the second charge rate shows what would happen if you adjusted 3 of the numbers down to account for Tesla's rounding of the Charge Rates. I find it very interesting that based on Tesla's numbers 3 of the Amperage draws produce the exact Miles Gained/KWh Used and in the second chart it shows that if 3 of the numbers are adjusted to account for Tesla's possible rounding. every scenario then uses exactly to a hundredth of a KW burned to yield the same Mileage Gained.
Model Y Using Tesla Gen3 Wall Connector with Published Miles per Hour Charge Rate
Current DrawKWh Drawn/HourMiles Gained/hr.KWh burned/Mile of Charge
48 Amps1.152420.27428
40 Amps0.960360.26667
32 Amps0.768290.26489
24 Amps0.576210.27428
16 Amps0.384140.27428
12 Amps0.288100.288
Model Y Kilowatts Used, but Changing Published Charge Rates Down by 0.5 Miles of Range
48 Amps1.152420.27428
40 Amps0.960350.27428
32 Amps0.768280.27428
24 Amps0.576210.27428
16 Amps0.384140.27428
12 Amps0.28810.50.27428
Only the following were adjusted by a 1 Mile Range 12 Amps, 32 Amps, 40 Amps. To account for possible rounding of the Charge Rate by Tesla.
The Range was arrived at by simply dividing the Watts (Kilowatts multiplied by one thousand) used by the Miles Gained
 

45thParallel

Member
Sep 5, 2021
286
270
Minnesota
Here is what I came up with using Tesla's Published Charge Rate for the Model Y and the second charge rate shows what would happen if you adjusted 3 of the numbers down to account for Tesla's rounding of the Charge Rates. I find it very interesting that based on Tesla's numbers 3 of the Amperage draws produce the exact Miles Gained/KWh Used and in the second chart it shows that if 3 of the numbers are adjusted to account for Tesla's possible rounding. every scenario then uses exactly to a hundredth of a KW burned to yield the same Mileage Gained.
Model Y Using Tesla Gen3 Wall Connector with Published Miles per Hour Charge Rate
Current DrawKWh Drawn/HourMiles Gained/hr.KWh burned/Mile of Charge
48 Amps1.152420.27428
40 Amps0.960360.26667
32 Amps0.768290.26489
24 Amps0.576210.27428
16 Amps0.384140.27428
12 Amps0.288100.288
Model Y Kilowatts Used, but Changing Published Charge Rates Down by 0.5 Miles of Range
48 Amps1.152420.27428
40 Amps0.960350.27428
32 Amps0.768280.27428
24 Amps0.576210.27428
16 Amps0.384140.27428
12 Amps0.28810.50.27428
Only the following were adjusted by a 1 Mile Range 12 Amps, 32 Amps, 40 Amps. To account for possible rounding of the Charge Rate by Tesla.
The Range was arrived at by simply dividing the Watts (Kilowatts multiplied by one thousand) used by the Miles Gained
your calculations are in line with my finding the most efficient charging is at 40 Amp circuit breaker, then 50 Amp, followed by 20/30 and then 60 Amp. But the cost of charging at home is low, so it is not going to make a significant impact. I am expecting my Tesla next month and I do plan to test this out for a month each and check the power consumption. More of a curiosity than anything.
 

MikeHolliday

Member
May 9, 2020
377
275
Worthington, Ohio
I think that you are missing my point. Look at the second chart. I find it literally impossible that I can change 3 of the charge rates by either .5 or 1 mile difference and they all end up having the exact wattage consumption. I think that if you look at Tesla's exact numbers you will find that they all have the exact efficiency.
 

MachAF

Member
Feb 3, 2020
32
19
CZI
your calculations are in line with my finding the most efficient charging is at 40 Amp circuit breaker, then 50 Amp, followed by 20/30 and then 60 Amp. But the cost of charging at home is low, so it is not going to make a significant impact. I am expecting my Tesla next month and I do plan to test this out for a month each and check the power consumption. More of a curiosity than anything.
I don't think you have type of equipment/controlled environment required to calculate the minuscule difference (a few watts maybe?)
 
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MikeHolliday

Member
May 9, 2020
377
275
Worthington, Ohio
I just used Tesla’s published data. I am sure they would be averages and not exact numbers. but they are a good basis for comparison.
So, if you looked at Tesla's numbers, then your errors are caused by you using the breaker size and not the true amperage draw. Ohm's Law = Voltage X Amperage = Watts, 1,000 Watts=1 Kilowatt. If you follow my numbers you will see how the much more accurate, because they are usi g the wattage (or Kilowatts) that you are actually using and paying for in this situation.
 

jm404

Member
May 27, 2021
149
365
Atlanta
You can buy 4/3 MC Cable for about $6.25/ft. at Wire and Cable Your Way -- 4/3 MC Cable w/ Ground

I have been buying 95% of my cable here for the last 10 years. They have great service...

Hard wiring is the only way to go. NEMA 14-50 outlets are not designed to be Plugged and Unplugged on a regular basis. They will fail.

Just going to tack on here for anyone reading this in the future. MC is heavy and difficult to work with. I had a 60 foot run, the beginning of which was fairly complicated (I had to start at the panel since I wanted to use every inch of cable available). This meant the first part of the run, in my basement over ductwork and plumbing, required moving the entire 60' roll. The further I got the less cable and it was easier. In hindsight I probably would've looked into EMT or some other conduit, where I could hang the relatively lightweight conduit then run XHHW or THHN through it.

Also terminating the 4/3 in a box was something else... it's shocking how difficult this stuff is to work with compared to 12/2 or even 10/2

And finally, my plan was to run MC in the garage all the way to the charger. It's XHHW so wet rated. But I'm going to go ahead and run EMT so I can get it tucked tight into the corners
 

MachAF

Member
Feb 3, 2020
32
19
CZI
Just going to tack on here for anyone reading this in the future. MC is heavy and difficult to work with. I had a 60 foot run, the beginning of which was fairly complicated (I had to start at the panel since I wanted to use every inch of cable available). This meant the first part of the run, in my basement over ductwork and plumbing, required moving the entire 60' roll. The further I got the less cable and it was easier. In hindsight I probably would've looked into EMT or some other conduit, where I could hang the relatively lightweight conduit then run XHHW or THHN through it.

Also terminating the 4/3 in a box was something else... it's shocking how difficult this stuff is to work with compared to 12/2 or even 10/2

And finally, my plan was to run MC in the garage all the way to the charger. It's XHHW so wet rated. But I'm going to go ahead and run EMT so I can get it tucked tight into the corners
Exactly why certain folks here recommended 6/2 MC....
 
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MikeHolliday

Member
May 9, 2020
377
275
Worthington, Ohio
1.) Do not use solid core wire, used stranded. Solid core does like to bend.

2.) Most people are only pulling 4/2 for a Tesla Wall Connector or other brand wall connect. 2 Conduitors and a ground is much easier to pulle than 3 Conductors and a ground...
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,051
8,659
Boise, ID
1.) Do not use solid core wire, used stranded. Solid core does like to bend.
They're talking about 4 gauge wire. I am pretty well certain that doesn't even exist as solid core--it's all stranded at that huge thickness. I don't think you can get solid core thicker than about 10 gauge? Maybe 8 gauge?
 

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