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Discussion Starter · #1 ·
Hi everyone,
My L2 charger was re-installed at a new place we moved into and when the electrician finished installing he asked me to test is. Which we did and the Audi app is saying it’s charging at 6.5 kW?

that seems really slow considering this is a 32 amps L2 charger.

or is this what I’m supposed to get?

thanks!
2158
 

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32A x 240V = 7680 W (theoretical max). What is the circuit size you're working off?
 

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There will always be charging losses. With both the Audi charger and my wall charger running at 9.6kW, the car reports 8.8kW, so about 91.6% efficiency.

Using the same efficiency number for 32 amps would net about 7kW, so it's not that far off. You might see if the electrician can confirm whether or not the charger is pulling the proper amount of current while charging. If it is, you can chalk it up to normal losses. If it's not pulling the proper amount, further troubleshooting could be required.
 

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Discussion Starter · #4 ·
Thanks everyone! I’m on a 50 amp breaker, the electrician said it might be pulling 208 volts instead of 220 volts, he said that’s normal with SCE in our service area. If I do the math using 208volts then it’s right on spot.
 

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Discussion Starter · #5 ·
Hi everyone,

I just noticed on my SCE bill that it says "Service Voltage 240". So in this case I'm actually getting 240v and not 208v? Because if that's the case then there's something the electrician messed up during installation?
 

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208v is the line-to-line voltage on a 3-phase service. You do not have 3-phase service to your house if it's a standard residential house. 208v comes from 120v times the square root of 3 (the three phases).
Your service voltage of 240 is the standard for virtually every house in the United States.
 

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What did this charger give you at the old location?
If it says it's a 32 amp charger then sounds like you are receiving what you are suppose to get.
32 amps X 240V = 7.7 kW gross power draw; 6.5.kW [indicated on car] / 7.7 kW [gross power draw] = 84% efficiency which is about right.
 

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Discussion Starter · #8 ·
What did this charger give you at the old location?
If it says it's a 32 amp charger then sounds like you are receiving what you are suppose to get.
32 amps X 240V = 7.7 kW gross power draw; 6.5.kW [indicated on car] / 7.7 kW [gross power draw] = 84% efficiency which is about right.
I was getting 7.7 on my Model S, and I had a 40 amp breaker with the same 32 amp max output charger. I was charging at 23 miles / hour. I'm not even getting close to this currently.
 

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I was getting 7.7 on my Model S, and I had a 40 amp breaker with the same 32 amp max output charger. I was charging at 23 miles / hour. I'm not even getting close to this currently.
As you can see 32 amps times 240 V is 7.7kW gross power draw off the line. There are heat losses in the charger, cable and car wiring. So how the Model S can report 7.7 kW into the car is a mystery that only Tesla can explain. The miles/hour calculation has to do with the car's overall efficiency. The Model S is overall more efficient than an eTron so that might explain the apparent higher charging speed. If your charger is truly a 32 amp charger then you are getting what you are suppose to get into the eTron.

What charger are you using?
 

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Discussion Starter · #10 ·
As you can see 32 amps times 240 V is 7.7kW gross power draw off the line. There are heat losses in the charger, cable and car wiring. So how the Model S can report 7.7 kW into the car is a mystery that only Tesla can explain. The miles/hour calculation has to do with the car's overall efficiency. The Model S is overall more efficient than an eTron so that might explain the apparent higher charging speed. If your charger is truly a 32 amp charger then you are getting what you are suppose to get into the eTron.

What charger are you using?
Thanks, Bill!

This is the charger I'm using a Siemens hardwired charger. Thanks again for the explanation.
 

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It might be that Tesla is doing the reverse calculation are just guestimates the input charge rate. It is not that hard, after all, but it is a guestimate, nothing more. I'd rather know what the actual rate at the battery input is, and not some hypothetical one at the input into charger.
 

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Discussion Starter · #12 ·
It might be that Tesla is doing the reverse calculation are just guestimates the input charge rate. It is not that hard, after all, but it is a guestimate, nothing more. I'd rather know what the actual rate at the battery input is, and not some hypothetical one at the input into charger.
I agree. It’s just weird to see when I plugin the Etron to charge “~14 hours to complete” when my 100D charger much faster a much bigger battery.

this is not a complaint as I think the Etron is superior in build quality and comfort. It’s more of a if something is wrong on my end, I’d like to fix it. But seems like this is what it should be so thanks again everyone!
 

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It’s just weird to see when I plugin the Etron to charge “~14 hours to complete”
What charge rate is shown in the app? I am typically charging slow overnight at 3.5kW effective and it does not take 14 hours. Regular daily commute is ~3.5hrs of charge, longer trips can take 8 hrs at this rate. I am deliberately throttling the charger, mind you, given that my local operator charger extra for peak / average consumption rate variation (when the rate difference is below 90%).
 

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Discussion Starter · #14 ·
What charge rate is shown in the app? I am typically charging slow overnight at 3.5kW effective and it does not take 14 hours. Regular daily commute is ~3.5hrs of charge, longer trips can take 8 hrs at this rate. I am deliberately throttling the charger, mind you, given that my local operator charger extra for peak / average consumption rate variation (when the rate difference is below 90%).
I typically wait until my range is around 40-50 miles before I fully recharge the vehicle. On the attached screenshot charging from 74% @ 6.5 kwh shows 4 hours and 13mins to complete. Screen Shot 2021-07-12 at 2.01.20 PM.png
 

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I typically wait until my range is around 40-50 miles before I fully recharge the vehicle.
Understood, my preference is for more frequent but shallow charging.
On the attached screenshot charging from 74% @ 6.5 kwh shows 4 hours and 13mins to complete.
What is your typical figure of miles/kWh? The screen would imply you're charging to 100% SOC, which should be roughly 55-60 miles. At 6.5 kWh rate and 2.2 miles/kWh, that should be about 4.2 hours, which matches more of less what your app is showing (4hrs 13 minutes). 6.5kWh rate at 2.2 miles/kWh is 14.3 miles/hr rate. Yes, it is lower than Tesla, but so what?
 

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Discussion Starter · #16 ·
Understood, my preference is for more frequent but shallow charging.

What is your typical figure of miles/kWh? The screen would imply you're charging to 100% SOC, which should be roughly 55-60 miles. At 6.5 kWh rate and 2.2 miles/kWh, that should be about 4.2 hours, which matches more of less what your app is showing (4hrs 13 minutes). 6.5kWh rate at 2.2 miles/kWh is 14.3 miles/hr rate. Yes, it is lower than Tesla, but so what?
You're right on the spot :) Typically around 2.2 sometimes gets up to 2.4-2.6 :) But 2.2 is safe to say avarage, yes.

I don't mind that it's lower than Tesla, yes it costs more to charge but the vehicle itself is much nicer and has a much better build quality. Not a fan of the touchscreens of the Etron, menu is very clunky and not too user friendly, but overall I like this vehicle a lot!
 

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I was getting 7.7 on my Model S, and I had a 40 amp breaker with the same 32 amp max output charger. I was charging at 23 miles / hour. I'm not even getting close to this currently.
Some more math:
If you charged the S100 to 100% SoC: 100000 wh / 6500 watts = 15.4 hours. eTron 86000 wh / 6500 watts = 13 hours total charge time.
S100 23miles/hr X 15 hours = 354 miles range. 100000 Wh / 354 miles = 282 Wh/mile.
eTron 220 miles range /13 hours = 17 miles/hour. 86000 Wh / 220 miles = 390 Wh/mile.

The reason the Tesla looks better on the charge rate is BC it gets more miles out of a Wh than the eTron. The eTron, however, should be compared against the Model X not Model S for efficiency.
See Teslike.com The Model X long range has 16% more available battery so comparing 75 MPH range the Model X still gets about 50 more miles on a full charge.

On a long trip Tesla drivers never hang around the Super Charger for full charge BC of the slow charge rate as the battery fills up. Thus on a full day of driving the eTron is not so far behind due to it's high flat charge rate to 80% and good charge rate to 100%.
 
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