What is Level 1 EV Charging? [Advanced]

Level 1 EV charging is the simplest and most widely accessible charging method for electric vehicles (EVs). It uses a standard 120-volt AC outlet commonly found in households across the United States and other countries.

With a Level 1 charger, your Electric Car can charge directly from a 120V or 240V wall socket without the need for specialized equipment.

Who Should Consider Level 1 Charging?

Level 1 charging is ideal for:

• Daily commuters driving less than 40–50 miles a day.
• Plug-in hybrid electric vehicle (PHEV) owners with smaller batteries, such as the Toyota Prius Prime or Chevrolet Volt.
• EV owners with secondary cars, who primarily use their EVs for short trips.
• Temporary renters who cannot install a Level 2 charger.

How Level 1 Charging Works: A Technical Overview

Level 1 charging uses a standard 120V household outlet to charge electric vehicles (EVs). It operates at 12-16 amps, providing up to 1.44 kW of power.

The process involves:

1. Power Conversion: The charger converts 120V AC from the outlet into DC power required by the EV battery.
2. Power Delivery: The onboard charger in the vehicle manages the DC power flow into the battery, ensuring safe charging.
3. Slow Charging: It delivers a slow charge, typically adding 3-5 miles of range per hour.

Level 1 charging is suitable for overnight or low-mileage daily use.

Electrical Specifications of Level 1 Charging

Voltage and Current:

Level 1 chargers use 120 volts (V) of alternating current (AC) and typically operate at 12–16 amps (A). This configuration delivers a maximum power output of approximately 1.44 kilowatts (kW).

Calculation:

Power (Watts) = Voltage (Volts) × Current (Amps) → 120V × 12A = 1,440W (or 1.44 kW).

Power Flow:

The charger converts the 120V AC power from the grid into a form suitable for the EV’s onboard charger, which then manages the process of storing energy in the vehicle’s battery.

Components Involved in Level 1 Charging

1. Standard Outlet (NEMA 5-15 or NEMA 5-20)

Level 1 chargers are designed to plug into typical 120V household outlets, like a NEMA 5-15 (three-prong) socket.

These outlets have a maximum capacity of 15–20 amps, making them suitable for low-power applications like Level 1 charging.

2. EVSE (Electric Vehicle Supply Equipment)

The Level 1 charging cable, often referred to as the EVSE, acts as the intermediary between the wall outlet and the EV.

• Current Regulation: Ensures the current delivered to the EV doesn’t exceed the safe operational limit of the outlet or vehicle.
• Safety Features: Includes ground fault circuit interrupters, surge protection, and thermal sensors to prevent overheating.

3. Onboard Charger (OBC)

Located inside the vehicle, the onboard charger (OBC) is responsible for converting the incoming AC power to direct current (DC), which the battery requires for storage.

• Efficiency: The OBC typically operates at 90–95% efficiency, with minimal energy loss during conversion.

The Level 1 Car Charger Working

1. Plugging In:
   The user connects the EVSE plug to the EV’s charging port and the other end to a standard 120V outlet. The EVSE performs a quick self-diagnostic check to ensure the outlet is properly grounded and that no electrical faults exist.
2. Handshake Protocol:
   A communication handshake occurs between the EVSE and the EV. Using the SAE J1772 communication standard (for non-Tesla vehicles), the EVSE and EV exchange data, such as the EV’s current battery level and the maximum allowable current.
3. Current Flow Initiation:
   After the handshake, the EVSE allows current to flow from the outlet to the vehicle’s onboard charger. The OBC converts the AC power to DC and regulates the charging speed based on the battery’s state of charge (SOC).

Battery Charging Dynamics of Level 1 Charger

1. State of Charge (SOC) and Charging Curve:

• Constant Current (CC): The charger supplies a steady current until the battery reaches a specific voltage threshold.
• Constant Voltage (CV): Once this threshold is reached (e.g., 4.2V per cell in lithium-ion batteries), the current gradually decreases to prevent overcharging.

2. Energy Storage Efficiency:

Lithium-ion batteries, commonly used in EVs, exhibit 95–98% Coulombic efficiency, meaning most of the energy supplied is effectively stored.

3. Charging Speed:

At 1.2–1.4 kW, Level 1 charging adds about 3–5 miles of range per hour, depending on vehicle efficiency. For example:

• Tesla Model 3: Adds ~4 miles/hour (efficiency ~4.2 miles/kWh).
• Chevrolet Bolt: Adds ~5 miles/hour (efficiency ~4.6 miles/kWh).

Thermal Management

1. Heat Generation:

During charging, electrical resistance generates heat in both the charging cable and the battery. The EVSE is equipped with thermal sensors to detect overheating and automatically shuts down power if thresholds are exceeded.

2. Battery Cooling:

Many EVs feature active thermal management systems, such as liquid cooling, to regulate battery temperature during charging.

Safety Mechanisms in Level 1 Charging

1. Ground Fault Protection:

The EVSE includes a Ground Fault Circuit Interrupter (GFCI) that shuts off power within milliseconds if a ground fault is detected.

2. Surge Protection:

Protects the EV and onboard electronics from voltage spikes.

3. Automatic Shutoff:

Charging stops automatically when the battery is full, preventing overcharging and prolonging battery life.

Energy Efficiency and Losses

1. Conversion Losses:

Onboard AC-to-DC conversion leads to energy losses of 5–10%, depending on the OBC’s design.
Resistance in the charging cable and connectors can cause minor additional losses (~2–3%).

2. Overall Efficiency:

Level 1 charging typically achieves an overall efficiency of about 80–90%.

Level 1 chargers typically come bundled with the vehicle. These chargers plug directly into a 120V outlet and draw power to charge the vehicle’s battery.

• Real Examples:
  1. Tesla Mobile Connector: Comes with every Tesla and supports Level 1 charging.
  2. ClipperCreek LCS-25P: Compatible with most EVs and comes with enhanced safety features.
  3. ChargePoint Home Flex (Portable Mode): Though primarily a Level 2 charger, it offers Level 1 compatibility with an adapter.

Charge Speed of Level 1 Charging

A standard Level 1 charger operates at 120V and delivers 12 to 16 amps. At this rate, the charging speed is approximately 1.2 kW/hour, which equates to around 4-5 miles of range per hour for most EVs. For example:

• A Nissan Leaf (40 kWh battery) requires 35–40 hours to charge fully from 0%.
• A Chevrolet Bolt (60 kWh battery) can take up to 50 hours for a full charge.

Charging Rate

Level 1 charging adds approximately 3–5 miles of range per hour. For a typical daily commute of 30 miles, you would need around 6–10 hours of charging time, making it perfect for overnight use.

Key Features of Level 1 Charging

🟩 Standard 120V Outlet: Uses a common household outlet for power.

🟩 Slow Charging Speed: Adds about 3-5 miles of range per hour of charging.

🟩 Convenient for Home Use: Ideal for overnight or low-mileage daily charging.

🟩 12-16 Amps Current: Operates at a current range suitable for basic charging needs.

🟩 No Installation Required: No need for specialized equipment or installation beyond the standard outlet.

🟩 Safe and Simple: Managed by the vehicle’s onboard charger, ensuring safe power conversion and delivery.

Advantages of Level 1 Charging

Accessibility and Convenience

Level 1 chargers use standard outlets, so there’s no need to hire an electrician or install expensive equipment. 98% of U.S. homes have accessible 120V outlets, making Level 1 charging the most accessible option for new EV owners.

Cost-Effectiveness

Level 1 charging is highly economical. Here’s an example:

• Charging a 40 kWh Nissan Leaf from 0 to 100% using Level 1 costs around $5–7, assuming an electricity rate of $0.13/kWh. This is far cheaper than gasoline for an equivalent distance.

Can Level 1 Charging Be Used for Long Road Trips?

Level 1 charging is not practical for long road trips due to its slow charging speed. For instance:

• If you drive 200 miles per day, a Level 1 charger would need 40–50 hours to recharge a typical EV.
  For road trips, Level 2 chargers or DC fast chargers found at public charging stations are better suited, offering charging speeds up to 50–250 kW/hour.

Is Level 1 Charging Safe for My Home?

Yes, Level 1 charging is generally safe if your home’s electrical system is up to code. Ensure:

• Outlets are properly grounded.
• Avoid using extension cords unless rated for high current.
• Regularly inspect the charger for wear and tear.
  Most Level 1 chargers, like the ClipperCreek LCS-20, include built-in safety features like surge protection and automatic shutoff.

Can Level 1 Charging Handle Cold Weather?

Cold weather can reduce charging efficiency by up to 20-30%. This is due to increased energy demands for battery thermal management.
Tips for efficient winter charging:

• Precondition the car while it’s plugged in.
• Keep the charger and vehicle in a garage to minimize temperature drops.

How Does Level 1 Charging Compare to Public Charging Stations?

Speed: Public DC fast chargers deliver up to 350 kW/hour, recharging most EVs in 15–45 minutes.
Cost: Public chargers often cost $0.25–$0.50/kWh, making them 2–4 times more expensive than home Level 1 charging.

Use Level 1 charging for daily commutes and public stations for road trips or emergencies.

Level 1 Charging vs. Level 2 Charging

Charging Speed Comparison

• Level 1: Adds 4–5 miles of range per hour (suitable for daily short trips).
• Level 2: Adds 20–25 miles of range per hour, charging a 40 kWh battery in 4–6 hours.

Cost and Installation Differences

• Level 1: No additional installation costs; uses existing outlets.
• Level 2: Requires professional installation costing between $500–$2,000 for the equipment and labor.

FAQs about Level 1 Charging

How fast is a Level 1 EV charger?

It adds 3–5 miles of range per hour.

Can Level 1 charging damage my car battery?

No, Level 1 charging is slow and gentle, minimizing battery stress.

What is the cost of Level 1 charging?

Charging a typical EV battery costs between $5–$10, depending on electricity rates.

Are there any portable Level 1 chargers?

Yes, options like the JuiceBox 40 Mobile Charger are portable and reliable.

Can I use an extension cord?

It’s generally not recommended unless it’s rated for outdoor use and high current.

Conclusion

Daily commuters and overnight charging benefits from Level 1 charging as a straightforward and affordable solution for electric vehicle power. There are two advantages of this charger which include using standard 120V outlets and the ability to charge at a slow pace that works for both brief trips and additional automobiles. This charging method provides basic power for most EV drivers at an economical rate but it cannot charge vehicles for extended traveling. Recovering charging speed requires either Level 2 or DC fast chargers as better alternatives.