Levels of Charging
There are three levels of EV charging:
- Level 1 charging uses normal household 120 VAC outlet, which can put around 1.2kWh into the EV every hour.
- Level 2 charging uses 240 VAC outlet, which is also available in normal households, such as electric range or electric cloth dryer. With a 32 amperage charger, it can put around 7.68 kWh into the EV per hour.
- Level 3 charging uses direct current to charge EV, such as Tesla’s fast charging network. It can put 50 kWh to 350 kWh into EV per hour. Some charging companies are installing higher output chargers.
Level 1 and Level 2 charger supply AC energy to the EV. The EV uses its built-in AC/DC converter to change AC energy into DC energy to charge the EV battery. Due to the converter size, EV can only convert a certain amount of AC energy at a time.
Level 3 charger supplies DC energy to the EV. EV can use the DC energy to charge the EV battery directly. Since the converter is outside of the car, it can be designed to convert much more energy for the EV.
Cost of installing a NEMA 14-50 Power Outlet
Tesla recommends NEMA 14-50 power circuit or power outlet with 6 AWG (American Wire Gauge), Copper Wire for charging Tesla cars at home. A Tesla certified contractor quoted me $1,495 to install a NEMA 14-50 outlet in my garage. The distribution panel is in the basement. The contractor needs to modify the distribution panel to make room for the 50A double-pole, GFCI (Ground Fault Circuit interrupter) breaker, pull thirty feet 6 AWG wires from the basement to the garage and install a NEMA 14-50 power outlet. Do I need the level 2 outlet?
Do I need the NEMA 14-50 power Outlet?
Here are some basic driving information. The daily drive is 24 miles round trip to work, with 100 miles some days for errands. The errands days can be scheduled ahead of time. There are at least ten hours each night that the Model Y parks inside the home garage.
According to US Government’s Fuel Economy Website, Tesla Model Y uses 28 kWh to run 100 miles, which averages to 3.6 miles per kilo-watt-hour (kWh). After running 1,228 miles on my Model Y, the trip monitoring display on the Model Y shows 250 Wh per mile. That translates to four miles per one kWh.
With at least ten hours home charging time, the Model Y can add 10 kWh per night, which equals 40 miles, 16 more miles than the daily commute. If the Model Y drives 100 miles, there are 63 miles remaining on battery after the trip (272 max mile x (100 – 20 – 20)% = 163 mile). After charging over-night, it will have at least 103 miles usable range with 54 miles in battery reserve (272 max mile x 20% = 54.4 mile), which is more than enough for next day’s commute. Additionally, there are two Tesla Fast Charger Stations within five miles of my home. So if situation requires, I can charge the Model Y in a fast charger station.
NEMA 14-50 power Outlet with Georgia EV Charging Rebates justifiable?
Georgia power offers $250 rebate if a customer installs a Level 2 EV charger at home. Georgia power also offers three rates for charging EV:
- Super Off-peak rate is 1.7 cent/kWh between 11 PM to 7 AM
- Off peak hours rate is 7.9 cent/kWh, from June to September, weekdays 2 p.m. to 7 p.m
- Peak hours with 23 cent/kWh, which is the time not in Super Off-Peak and Off Peak
My current rate of power is 11.7 cent/kWh with Georgia Power.
If a level 2 outlet is installed, the Tesla can be charged at super off-peak rate of 1.7 cent/kWh. That would save 10 cent/kWh. For the installation price of $1495 for a NEMA 14-50 Power Outlet, the break even point is 12,450 kWh (with $250 installation rebate). That is 49,800 miles (Model Y uses 1 kWh for 4 miles).
Conclusion
With the super off-peak rate of charging the EV, a level – 2 outlet is justifiable. But with one EV at this time and 24 miles round trip commute, a level – 2 outlet is not required. However, if I purchase a second EV, then I will consider a level -2 charger so both EV can be charged to desired battery level over night.