32A vs 40A EV Charger: Charging Speed, Cost & Which One to Choose
32A and 40A are the two most popular residential Level 2 EV chargers. They differ in charging speed, electrical upgrade requirements and installation costs. This article compares their specifications and recommended use cases to help you choose the right residential EV charger.
What does the Amperage Rating Mean for EV Chargers?
An ampere (A) is the unit used to measure electric current. For an EV charger, the amperage indicates how much current the charging equipment can provide to the vehicle.
At the same voltage, a higher available charging current provides more charging power and can reduce charging time, provided that the EV and electrical system can support it.
What is a 32-amp EV Charger?
A 32 amp EV charger is a residential Level 2 AC charging station with a maximum rated output of 32A. On a 240V circuit, it can deliver approximately 7.7 kW of power, adding about 25 miles of range per hour.
What is a 40-amp EV Charger?
A 40 amp EV charger is a residential Level 2 AC charging station with a maximum rated output of 40 amps. On a 240V circuit, it delivers approximately 9.6 kW of power, adding about 30 miles of range per hour.
Key Differences Between 32-Amp and 40-Amp Chargers
Charging Speed and Power
A 32-Amp charger delivers approximately 7.7 kW of power. Taking a 60 kWh battery as an example, it takes about 8 hours to fully charge, making it ideal for overnight charging while parked; a 40-Amp charger delivers 9.6 kW, and the same 60 kWh battery can be fully charged in just 5–6 hours, offering significantly higher charging efficiency.
Circuitry and Installation Requirements
A 32A charging station is typically paired with a 40A circuit breaker, requiring minimal modifications to the home’s existing electrical system. A 40A charging station requires a 50A circuit breaker, placing higher demands on the capacity of the home’s electrical panel and wiring. Many older homes have wiring that does not meet these specifications, necessitating the replacement of thicker wires or even an upgrade to the electrical panel.
Installation Costs
The overall installation cost for a 32A charging station is lower, as most households do not need to undertake major electrical modifications. The 40A solution involves higher component costs, and if an upgrade to the distribution panel or replacement of wiring is required, the total installation cost will increase further.
Portability and Flexibility
Both 32A and 40A EV chargers are available in portable and wall-mounted configurations. Portable chargers offer greater flexibility for temporary or multiple-location charging, while wall-mounted or hardwired chargers are better suited to permanent home installations.
Future-Proofing
If you plan to switch to an electric vehicle with a larger battery capacity in the future, a 40A charging station provides greater charging headroom and may reduce the need for another circuit upgrade in the short term. Although a 32A charging station meets your current needs, if your future vehicle has a higher charging limit and a larger battery, the charging speed will become a bottleneck, potentially requiring you to retrofit the circuit and upgrade the equipment.
Quick Comparison
| Specifications | 32A Charger | 40A Charger |
|---|---|---|
| Voltage | 240V | 240V |
| Maximum Power | Approx. 7.7 kW | Approx. 9.6 kW |
| Charging Speed | Slower | Faster |
| Circuit Requirements | Typically 40A | Typically 50A |
| Installation Difficulty | Generally easy | May require a higher-capacity circuit |
| Daily Commuting | Usually sufficient | Offers greater charging capacity |
| Cost | Generally lower | Generally higher |
| Future Adaptability | Good | Better |
| Best For | Most everyday drivers | High-mileage drivers / Those seeking faster charging |
Factors to Consider When Choosing Between 32-Amp and 40-Amp EV Chargers
Vehicle Battery Capacity and Onboard Charger Limit
Battery capacity directly affects charging time. If you own a long-range electric vehicle with a high-capacity battery, using a 40-amp (9.6 kW) charger can significantly reduce charging time. For models with smaller battery capacities, a 32-amp (7.7 kW) charger is sufficient for overnight charging.
It’s also important to note the current limit of the vehicle’s onboard charger (OBC). If the vehicle itself can only accept a maximum current of 32 A, installing a 40-A charging station will not result in faster charging speeds.
Daily Driving Habits
If you primarily take short trips and have ample time to park and charge your vehicle overnight, a 32-amp charging station is fully capable of replenishing the daily energy consumption. If you drive long distances daily, your vehicle consumes a significant amount of energy, and you need to replenish a large portion of your range each time, the higher power output of a 40-amp charging station can speed up the charging process.
32A vs. 40A: How Much Faster Is 40A?
A 40A home charging station has an output power of 9.6 kW. Compared to the 7.7 kW of a 32A station, this represents a theoretical increase in charging power of about 25%, allowing for more energy to be charged per unit of time.
To charge 40 kWh, a 32A charger takes 5.2 hours, while a 40A charger takes about 4.2 hours—saving 1 hour; to charge 60 kWh, a 32A charger takes 7.8 hours, while a 40A charger takes about 6.3 hours—saving 1.5 hours; and to charge 80 kWh, the time difference between the two can reach 2.1 hours.
The above figures are theoretical values under ideal conditions. Actual charging times are affected by battery temperature, BMS power reduction, and line losses. If the vehicle’s onboard charger is limited to 32A, charging speed will not increase even if a 40A charging station is installed.
32A vs. 40A EV Chargers: Charging Time Comparison
| Charging Capacity Required | 32A (approx. 7.7 kW) | 40A (approx. 9.6 kW) |
|---|---|---|
| 10 kWh | Approx. 1.3 hours | Approx. 1.0 hour |
| 20 kWh | Approx. 2.6 hours | Approx. 2.1 hours |
| 30 kWh | Approx. 3.9 hours | Approx. 3.1 hours |
| 40 kWh | Approx. 5.2 hours | Approx. 4.2 hours |
| 50 kWh | Approx. 6.5 hours | Approx. 5.2 hours |
| 60 kWh | Approx. 7.8 hours | Approx. 6.3 hours |
32-Amp and 40-Amp EV Chargers: Which One Is Better for Your Home?
Choose a 32A EV Charger If
- Your daily commute is of moderate distance, and you have ample time to park and charge overnight
- Your vehicle’s onboard charger supports a maximum input current of only 32 amps
- Your home’s electrical panel has limited capacity, and you don’t want to incur the extra cost of a circuit upgrade
- You only own one EV and have no immediate plans to purchase a second one
Choose a 40A EV Charger If
- You drive long distances daily and want to recharge more quickly
- Your vehicle’s onboard charger supports a 40-amp charging input
- Your home’s electrical system has ample capacity to handle a higher power load
- You plan to switch to a model with a higher-capacity battery or add a second EV in the future, so you want to reserve charging capacity
Conclusion: Both 32A and 40A charging stations have their own advantages; choose based on your needs. Whether you need stable daily charging or want to reserve capacity for future expansion, ZENCAR’s home EV chargers cover both specifications, providing safe and reliable charging solutions.
FAQ
Does a 40-amp charger require an upgrade to the electrical panel?
Whether an upgrade is needed depends on the available capacity of your home’s existing electrical panel. If there is sufficient capacity, no upgrade is necessary; if there is insufficient capacity, an upgrade is required.
Can both of these chargers be installed outdoors?
Both the 32A and 40A residential EV chargers can be installed outdoors, but you must select a model that meets the appropriate outdoor protection rating. Additionally, a licensed electrician must perform the wiring and waterproofing work to ensure long-term safety.
If your electric vehicle only supports a 32-amp charging current, can you use a 40-amp charger?
You can use a 40-amp charger, but the vehicle will only charge at 32 amps and will not achieve a faster charging speed.
Will a 40-amp charger damage my electric vehicle’s battery?
No, a 40-amp charger will not damage the battery. The vehicle’s onboard charger and Battery Management System (BMS) automatically control the current and power flowing into the battery.
Is a 40-amp electric vehicle charger compatible with all electric vehicles?
No. The actual charging current is determined by the vehicle’s onboard charger. If the vehicle only supports a maximum input of 32A, it will charge at 32A even if a 40A charger is installed.
Can I upgrade from a 32-amp charger to a 40-amp one later?
Yes, as long as your home’s electrical panel and wiring specifications meet the 40A load requirements, and your vehicle supports 40A charging, you can upgrade from a 32A to a 40A charger at a later date.
Is a 32-amp current sufficient for overnight charging?
For many drivers, a 32A Level 2 charger can provide enough energy for a typical overnight recharge. The actual amount of energy added depends on the vehicle’s charging efficiency, battery size, starting state of charge, and charging time.
How can you determine if your home’s electrical system can support a 40-amp charger?
Have a licensed electrician assess the remaining capacity of your main distribution panel, the current-carrying capacity of your wiring, and the circuit configuration to determine whether your home’s electrical system can handle a 40-amp charger.
Do high-current chargers pose safety hazards?
High-current chargers pose very low risk when installed in compliance with regulations and with properly matched wiring; however, if the circuit or cables do not meet standards or if installation is improper, safety hazards such as overloading and overheating may occur.
Can I connect a 32A electric vehicle charger to a NEMA 14-50 outlet?
Yes, a 32A electric vehicle charger can be connected to a NEMA 14-50 outlet, but the actual output current will be limited to 32A, which is lower than the outlet’s 50A rated capacity.
