BU-1004: Charging an Electric Vehicle

Learn about the different options charging an EV

If you own an EV, you want to pamper the battery and charge the car at home and at the office. The power requirements to charge a mid-sized EV is similar to that of an electric stove connected to a 40A, 240VAC circuit developing up to 9.6kW. Most mid-sized EVs carry a 6.6kW on-board charger designed for a 4- to 5-hour charge. (6.6kW is derived by multiplying 220V by 30A.)

On-board chargers are limited by cost, size and thermal issues. With the availability of three-phase AC power in most European residences, on-board chargers can be made smaller than with a two-phase system. Renault offers compact on-board chargers that range from 3–43kW.

The hookup to charge an EV is called the Electric Vehicle Service Equipment (EVSE) and must be installed by an electrician. There are three categories of charging.

Level 1 Cord-set connects to a regular household outlet of 115VAC, 15A (230VAC, ~6A in Europe). This singe-phase hookup produces about 1.5kW, and the charge time is 7 to 30 hours depending on battery size. Level 1 meets overnight charging requirements for e-bikes, scooters, electric wheelchairs and PHEVs not exceeding 12kWh.
Level 2 Wall-mount; 230VAC, 30A two pole, charges a mid-sized EV in 4 to 5 hours. This is the most common home and public charging station for EVs. It produces about 7kW to feed the 6.6kW on-board EV charger. The cost to install a Level 2 EVSE is about $750 in materials and labor. Households with a 100A service should charge the EV after cooking and clothes-drying to prevent exceeding the allotted household power.
Level 3 DC Fast Charger; 400–600VDC, up to 300A; serves as ultra-fast charging by bypassing the on-board charger and feeding the power directly to the battery. Level 3 chargers deliver up to 120kW to fill a Li-ion battery to 80 percent in about 30 minutes. The power demand is equal to five households.

In the 1990s and 2000s, EV makers made a concerted effort to develop a universal charging port for EVs and this resulted in the SAE J1772, a 5-pin connector carrying AC and data. The drawback is a charge time pursuant to Level 2 that takes several hours.

EV makers agree that the future of the EV lies in fast charging. While Level 2 only gains about 40km (25 miles) per hour charge, DC Fast Charging fills the battery to 80 percent in 30 minutes. This changes the EV from a commuter car into a touring vehicle, and EV marketing has started to push the concept.

Japan was first to introduce DC Fast Charging by developing the CHAdeMO connector for the Nissan Leaf and Mitsubishi MiEV. JEVS (Japan Electric Vehicle Standard) specified the connector that includes two large DC pins with communications pins for the CAN-BUS. The CHAdeMO standard was formed by TEPCO (The Tokyo Electric Power Company), Nissan, Mitsubishi, Fuji Heavy Industries (manufacturer of Subaru vehicles) and Toyota in 2008. It charges a battery at 500VDC and 125A with up to 62.5kW charging power. CHAdeMO stands for “CHArge on the Move;” Figure 1 illustrates the plug.

Figure 1: Japanese CHAdeMO DC Fast Charge plug developed in 2008. Nissan and Mitsubishi lead DC fast charging and developed CHAdeMO. It fast-charges at 500VDC and 125A, developing up to 62.5kW of power.

While the CHAdeMO connector performs well, the West lobbied against it, citing “technical issues.” The reason for this may be the “not invented in my backyard” syndrome as well as a standard that favors certain brands of cars. SAE rejected CHAdeMO in favor of their version.

After much delay, the SAE International J1772 Committee released the SAE DC Fast Charging standard in 2012, a system that is also known as the Combo Charging System (CCS). The delay caused a setback in building the CHAdeMO infrastructure and some argue that the postponement was deliberate.

To keep compatibility with Level 2 charging, CCS is based on the existing J1772 connector by adding two DC pins. When charging on AC, the circular connector provides AC power and communications to govern voltage, charge rate and end-of-charge. DC Fast Charging uses the same communications protocol but adds the DC pins. Figure 2 illustrates the charging connectors for AC and DC charging with the vehicle inlet.

Figure 2: SAE J1772 Combo Charging System (CCS). CCS allows Level 2 charging by connecting to the upper circular receptacle only, and Level 3 charging with a plug that includes the DC terminals.
SAE J1772 divides charging into four levels:
  • AC level 1: 120VAC, 12–16A, up to 1.92kW
  • AC level 2: 240VAC, 80A 19.2kW
  • DC level 1: 200-500VDC, up to 80A (40kW)
  • DC level 2: 200-500VDC, up to 200A (100kW)

The SAE Combo or CCS is the de facto global standard for Level 2 and 3 charging and Audi, BMW, Daimler, Ford, General Motors, Porsche and Volkswagen jointly announced their support in 2011. The Chevy Spark was the first EV to feature the SAE Combo in 2013. There is now talk to discontinue the CHAdeMO. To maintain compatibility with EVs featuring CHAdeMO, newer Nissan Leafs include an SAE J1772 port to allow Level 2 charging. Some charger manufacturers, including ABB, offer both charging plugs at their “pumps.”

Tesla Motors does not follow standards easily, and they came up with their own system. Their exclusive Supercharger fills a depleted battery to 80 percent in 40 minutes and gives a driving range of 270km. (Charging from 80–100 percent doubles the time.) While Tesla was criticized by some for introducing their Superchargers, others say that Tesla is way ahead of the game and did not want to wait for the world to get its standards right. Tesla is in discussions with Nissan and BMW to offer their Supercharger standard to these EV makers as well. They are also working on an inter-protocol charging adapter that can support the CHAdeMO and SAE J1772 systems.

Charging the Tesla S 85 on a Supercharger begins at a voltage of about 375V and 240A, consuming 90kW. As the battery fills, the voltage rises to about 390VDC and the current drops to roughly 120A. The initial 90kW into the 85kWh battery has a charge rate that is only slightly higher than 1C. After a brief moment, the C-rate falls to a comfortable 0.8C, and then goes down further, avoiding harmful battery stress that is related to ultrafast charging.

Battling three incompatible charging systems was not the plan for EV makers, but it occurred in part by not accepting available technologies and delaying their own standards. Tesla jumped ahead with their own technology and is investing heavily into building Superchargers and offering free charging; other EV makers have followed by also making charging free, at least for now. The resulting incompatibility has similarities with the railroads industry in the 1800s, when railway companies ran their trains on different track gauges. LP vs. 45 RPM, as well as Sony Beta vs. VHS are other examples of similar situation.

BMW with its SAE Combo Charging system chose 24kW rather than the more common 50kW for the DC Fast Charger. They reckon that 24 kW is cheaper, lighter and easier to install than a 50kW system. While 50kW would charge faster, the benefit is for a brief moment only before the charge acceptance degrades. Scaling down is especially apparent with the smaller i3 battery, as well as packs that cannot take the ultra-fast charge due to advanced age and other anomalies. Tests show that the 50 kW charger fills a battery to 80 percent in about 20 minutes; the 24 kW charger does it in roughly 30 minutes.

Doubling the power does not cut the charge time in half and moving up in the pyramid has diminishing returns. The main reason for powerful chargers relates to battery size. The BMW i3 carries a 22kW battery compared to the monster 85kW in the Tesla S 85. Both charging systems keep the charge C-rate at about 1C during DC fast charging to moderate battery stress levels.

DC fast charging is more complex in that it must evaluate the condition of the battery and apply a charge level that the battery can safely absorb. A cold battery must be charged slower than a warm one; the charge current must also be reduced when cells develop high internal resistance and when the balancing circuit can no longer compensate for cell mismatch. (See BU-410: Charging at High and Low Temperature

DC Fast Charging is not designed to fill the battery completely but to allow the vehicle to reach the next charging station. Using Level 2 is the preferred routine for everyday charging.

Table 3 summarizes the charge levels and times with Levels 1, 2 and 3. The charge times may not fully agree with advertised rates as the calculations are based on charging an empty battery to fully SoC; some EV makers consider the battery charged when it reaches 80 percent. The charge time also shortens as the battery fades because there is less to fill.

Charge levels Level 1

120VAC, 15A

240VAC, 30A**
Level 3
DC Fast Charge

400–600VDC, up to 300A
Driving Range 8km (5 mi)
per 1h charge
36km (22 mi)
per 1h charge
110, 270km (70, 168 mi)
per 30min charge
4.4kWh Toyota Prius 4h 1h N/A
16kWh Chevy Volt 12h 3h N/A
22kWh BMW i3 15h 4h 24kW: To 80% in 30 min
32kWh Nissan Leaf 16h 5h 50kW: To 80% in 20 min
60kWh Chevy Bolt 40h 10h 50kW: To 80% in 60min
90kWh Tesla S 85 60h 15h 120kW: To 80% in 40 min

Table 3: Estimated charging times on Electric Vehicle Service Equipment (EVSE). EVs carry the charging circuit on board and the most common is the 6.6kW system, Tesla has 10kW charger.

* Tesla EVs come with 10kW and 20kW chargers; Renault uses 3–43kW 3-phase on-board chargers
** A 30-amp EVSE needs a 40A circuit breaker some EVs come with larger on-board chargers

Last updated 2018-02-08


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Comments (11)

On February 9, 2016 at 8:01pm
Scott Drysdale wrote:

Correction to your Level 1, 2 and 3 charger descriptions:
Level 1 is correctly described (120VAC circuits are limited to 12 amps hence slowest charging rate)
Level 2 is a 2 pole NOT 2 phase circuit which allows for 240 VAC from the residential distribution panel by means of a 2 pole breaker which skips past the neutral connection. It is still a single phase circuit but offers up to 45 amps maximum if a 50 amp 2 pole breaker is used or 36 amps if the 40 amp two pole breaker is used etc. Typically these 240 VAC circuits enable recharging in 1/2 the time as do 120 VAC circuits because the current ability is doubled etc.

Level 3: is not an option for a residential service but available for 3 phase systems common to many commercial electrical services…...

On May 6, 2016 at 12:25am
Khalid nawaz wrote:

we would like to charge our country e bikes through 3 level of charging.Our country charging systems is locally made but it took long time to charge minimum 8 to 10 hours but most of the cases the charge is not full.We would like pl suggest what shall we do to charge in a quick mode.If you have any questions pl feel free to contact me.Thanks.

On September 2, 2017 at 2:59am
Slavko Radosavljevic wrote:

Offer fast and intelligent chargers and charging stations for all types of electric scooters. Charging times from 10 to 60 minutes.


The unit designed for the modern and complete treatment of all doors and tipva battery. Charging is completed in a time of 10 minutes to fill up to 2 hours envy of battery capacity.
For example,
BATTERY CHARGING100% IN JAST 10 - 60minutes.
PARS devices are universal devices designed for modern, efficient and complete treatment of all types &subtype; cells and battery types.
Devices hasPARS MB CPU module, which implements the relevant functions that make Universality, modernity, efficiency and complete treatment of the connected batteries.
UNIVERSALITY is achieved in treatment options:
- all battery types ( Pb, NiCd, NiMH, LiIon, LiPol i LiFe ) and subtypes
- batteries of different voltages and
- batteries of all capacities.
MODERNITY involves the use of modern technological capabilities in the field of power electronics.
Devices from PARS program can be:
- PARS devices with power module, CPU module, executive and information elements, and
- PARS Adapter devices that do not have the power module,and use external, appropriate AC or DC power supplies (chargers, rectifiers, power transformers, solar panels, wind, etc.) andenergy sources.
- Devices can also be designed for small, medium and large power.

TREATMENT TIME CAN BE from 10 min to 4 hours maximum and dependsby the battery capacity and type.
Complete treatment of the battery means that each unit is PARS MB CPU module programmed with algorithms that allow complete treatment. In this regard PARS device achieves 7 operations (such as 7 special devices needed for a high-quality battery maintenance), and:
- controlled battery state analyzer
- controlled battery discharger in 5-hoursregime with purpose to recognize the real capacity of the battery.
- controlled Ah capacity and other parameters of the battery
- controlled fast charge usingPARS RELAX method
- controlled detector of Battery Charge completion
- controlled battery capacity maintainer, and
- controlled battery conditioner using 3 cycles of discharging and fast charging
There is possibility Adjusting parameters according to the connected battery (type, subtype, voltage, capacity, charge current, discharge current and current maintenance charge level). Battery limit is adjusted according to the battery manufacturer’s instructions.
End of treatment (10 min to 60min) depend on the time of observed electro chemical conversion state.
With the appropriate PARS software, device can be connected to a PC via a USB port. Software is capable to display graphic of battery charging and discharging in real time, the possibility of reading the essential elements of the completion of charging when the device was not connected to computer, print, and save the results, the formation of reports, etc.

PARS program is applied in seven projects:
1. Devices for military and police needs
2. Rechargeable stations for growing need of the army and police
3. Rechargeable mobile stations for military needs
4. Rechargeable stations for battery mining lamps at protective helmets
5. For growing need for golf carts and battery stations on the golf terrains
4. Immobile and other wheelchair, scooters, bicycles and similar vehicles
5. Growing need for forklifts and other vehicles powered by batteries in service activities
6.Electromobile needs, and
7.The infrastructure (charging stations) on the road for battery electric vehicles
PARS program is very ambitious because it offers the possibility producing, marketing and use of modern appliances, new family in relation to which there are existing markets of the world, especially since it is now in use for over 4 billion batteries and over one billion devices mostly charger.

Author the program,
Slavko Radosavljevic, PhD
34 622797955 viber

On September 17, 2017 at 8:58am
william fitch wrote:

Question: How does the onboard charging system in an EV regulate the current into each cell (custom level to each cell), as an example the Nissan leaf’s 48 cell battery? If not from “outside over all” control, what is internal to each cell that regulates this? If this is present at each cell, is the regulation active or passive either from a mechanical or electrical perspective?

On October 16, 2017 at 6:49am
Lawrence Russo wrote:

As far as battery useful life is concerned (how many years of service), does using the supplied 120/15 amp service give longer battery life than the 240/40 amp service?  I drive a 2017, 60KWH Chevy Bolt.

On October 19, 2017 at 10:19am
dan wrote:

WHY do all these articles purposly exclude the fiat500e? Planed obsolesance? fiat didnt pay up? whay the blatant refusal to include?

On November 9, 2017 at 3:35pm
Bryan Keil wrote:

I do not see note of the 20 amp (16 amps nominal as the National Electrical code will only allow 80% of circuit value for continuous loads) 240 volt level 2 chargers here. My thought with my Focus having a 33.5 kw battery is that this charger would take around 8-10 hours to charge a depleted battery. 95 percent of the time I am only charging a half depleted battery and the 11 pm to 7 am low rates work. I chose this charger for 3 reasons. 1 is that it only costs about $225 dollars and has a plug similar to household ones, 2 is the fact that it is much less expensive to have this circuit installed and meets load calculations for an already highly loaded service and 3 is that I think that a 10C charge rate will be less stressfull on the battery over the years. my only question then would be is how much longer would the battery last at 10c compared to 5c? If I need a charge out and about, I would like to have the faster charger (6.6kw) available and use a level 3 (50kw) only when absolutely required and only put what I need. Any comments would be greatly appreciated.

On March 20, 2018 at 9:10pm
Dan Green wrote:

I’m getting a plug-in hybrid car with a 14-kWh battery capacity.
I do not plan to upgrade my garage outlets, because I am fine with 120-volt outlets to charge the car fully overnight (I do not need speed charging).  Are there any safety factors that I need to know about or worry about, with 120-volt 3-prong-outlet charging in my garage?  The electrical system is new (5 years) and up-to-code here in Massachusetts.  I just read about the 2018 Panamera E-Hybrid whose battery pack exploded and part of the house burned down when it was being charged overnight in Thailand.

On July 9, 2018 at 4:02pm
Scott Drysdale wrote:

Both Toyota and the Tesla e-vehicle batteries and battery management systems are the best and safest IMHO and Tesla suppliy their battery technology to BMW and several other quality European vehicle manufacturers.

Fiskar batteries are the choice for many US e-vehicle manufacturers as well as some Asian vehicle manufacturers. Note however that those US vehicle manufacturers lost a class action lawsuit a few years ago due to false advertising of 5 year + battery life in which the Fiskar batteries failed in less than 3 years.

The main issue was battery temperature management. In addition to battery temp increase due to charging and discharging, radiant heat from pavement in the summer months especially at lower latitudes caused premature failure of battery electrochemistry which is sensitive to excess heat and/or severe cold.

On July 9, 2018 at 4:12pm
Scott Drysdale wrote:

With respect to residential e-vehicle recharging…

Level 1 charging is considered inefficient and excessively time consuming requiring up to 16 hours for a full charge in most cases.

Level 2 charging (not to be confused with fast charging) is ideal for residential e-vehicle recharging as 8 hours is the worst case scenario for a full recharge….. that means under a worst case scenario your vehicle is fully recharged when you wake up to commute to work. Level 2 recharging also provides the widest possible range of configurations and options for all e-vehicles….. the rest depends on your accessory recharging system.

Ask any electrical engineer or electrician and they will agree that all attached and detached garages or carports should be wired for 240 VAC to enable a broader range of electrical power options such as a clothes dryer, power tools, electric space heaters and e-vehicles.

On September 6, 2018 at 1:43am
Mohammad Jamal Eddin Abu Khaled wrote: