This wiki is s summary of my Model S Charging findings first covered in this thread: What is the Most Efficient Charging Amperage?
In short, I am measuring the kWh required by my car to charge to 90% at various amperages, temperatures and battery discharge states and I'm looking to discover if there is an amperage that uses fewer kWh per Ideal Mile charged.
My findings are that there is no statistically significant difference in the parameters tested so far (but the experiment continues).
Data Sources:
- kWh: Powerhouse Dynamics SiteSage
- Charging Times & Mileages: VisibleTesla
- Charging: Tesla HPWC (80 amp)
Observations:
- 40 Amps does appear slightly worse than other amperages, but I believe there's an outlying sample that will wash out with more data.
Summary Table by Amperage
Summary by Amperage and Percentage of Battery Charged (rounded to 10%, assuming Max Ideal of 300 miles)
Summary by Ambient Outdoor Temperature at Charge Start (Rounded Down to Nearest 10 degrees F)
Summary by Normalized Time (Time to Gain 1 Ideal Mile Normalized to 80 Amp Charge)
In short, I am measuring the kWh required by my car to charge to 90% at various amperages, temperatures and battery discharge states and I'm looking to discover if there is an amperage that uses fewer kWh per Ideal Mile charged.
My findings are that there is no statistically significant difference in the parameters tested so far (but the experiment continues).
Data Sources:
- kWh: Powerhouse Dynamics SiteSage
- Charging Times & Mileages: VisibleTesla
- Charging: Tesla HPWC (80 amp)
Observations:
- 40 Amps does appear slightly worse than other amperages, but I believe there's an outlying sample that will wash out with more data.
Summary Table by Amperage
| Summary | ||||||
| Amps | # Samples | Min kWh/Ideal | Avg kWh/Ideal | Max kWh/Ideal | StdDev kWh/Ideal | Avg Minutes/Ideal |
| 20 | 1 | 0.286 | 0.286 | 0.286 | #DIV/0! | 3.4 |
| 40 | 3 | 0.292 | 0.295 | 0.303 | 0.006 | 1.8 |
| 60 | 4 | 0.278 | 0.285 | 0.297 | 0.008 | 1.1 |
| 80 | 3 | 0.264 | 0.284 | 0.298 | 0.018 | 0.9 |
| Grand Total | 11 | 0.264 | 0.288 | 0.303 | 0.011 | 1.4 |
Summary by Amperage and Percentage of Battery Charged (rounded to 10%, assuming Max Ideal of 300 miles)
| Deciles | ||||||
| Amps | # Samples | Min kWh/Ideal | Avg kWh/Ideal | Max kWh/Ideal | StdDev kWh/Ideal | Avg Minutes/Ideal |
| 20 | 1 | 0.286 | 0.286 | 0.286 | #DIV/0! | 3.4 |
| 60 | 1 | 0.286 | 0.286 | 0.286 | #DIV/0! | 3.4 |
| 40 | 3 | 0.292 | 0.295 | 0.303 | 0.006 | 1.8 |
| 10 | 1 | 0.303 | 0.303 | 0.303 | #DIV/0! | 1.9 |
| 40 | 2 | 0.292 | 0.292 | 0.292 | 0.000 | 1.8 |
| 60 | 4 | 0.278 | 0.285 | 0.297 | 0.008 | 1.1 |
| 20 | 2 | 0.278 | 0.281 | 0.284 | 0.004 | 1.1 |
| 30 | 1 | 0.297 | 0.297 | 0.297 | #DIV/0! | 1.1 |
| 40 | 1 | 0.283 | 0.283 | 0.283 | #DIV/0! | 1.1 |
| 80 | 3 | 0.264 | 0.284 | 0.298 | 0.018 | 0.9 |
| 30 | 1 | 0.298 | 0.298 | 0.298 | #DIV/0! | 0.9 |
| 50 | 2 | 0.264 | 0.277 | 0.290 | 0.018 | 0.9 |
| Grand Total | 11 | 0.264 | 0.288 | 0.303 | 0.011 | 1.4 |
| Deciles | ||||||
| Temp F | # Samples | Min kWh/Ideal | Avg kWh/Ideal | Max kWh/Ideal | StdDev kWh/Ideal | Avg Minutes/Ideal |
| 40 | ||||||
| 40 | 1 | 0.303 | 0.303 | 0.303 | #DIV/0! | 1.9 |
| 60 | 2 | 0.283 | 0.290 | 0.297 | 0.010 | 1.1 |
| 50 | ||||||
| 40 | 2 | 0.292 | 0.292 | 0.292 | 0.000 | 1.8 |
| 60 | 1 | 0.284 | 0.284 | 0.284 | #DIV/0! | 1.1 |
| 80 | 1 | 0.290 | 0.290 | 0.290 | #DIV/0! | 0.9 |
| 60 | ||||||
| 20 | 1 | 0.286 | 0.286 | 0.286 | #DIV/0! | 3.4 |
| 60 | 1 | 0.278 | 0.278 | 0.278 | #DIV/0! | 1.1 |
| 80 | 2 | 0.264 | 0.281 | 0.298 | 0.024 | 0.9 |
| Grand Total | 11 | 0.264 | 0.288 | 0.303 | 0.011 | 1.4 |
| Norm Minutes | ||||||
| Temp F | # Samples | Min of Norm Min/Ideal | Average of Norm Min/Ideal | Max of Norm Min/Ideal | StdDev of Norm Min/Ideal | Avg Minutes/Ideal |
| 20 | 1 | 0.84 | 0.84 | 0.84 | #DIV/0! | 3.4 |
| 40 | 3 | 0.87 | 0.91 | 0.94 | 0.033 | 1.8 |
| 60 | 4 | 0.84 | 0.85 | 0.86 | 0.010 | 1.1 |
| 80 | 3 | 0.86 | 0.87 | 0.89 | 0.016 | 0.9 |
| Grand Total | 11 | 0.84 | 0.87 | 0.94 | 0.033 | 1.4 |
