When comparing Level 2 EV chargers, amperage is the single specification that most directly determines charging speed. Choose too little and your battery may not fully recover overnight. Choose more than your vehicle can use and you have paid for capability you will never access. This guide explains every amperage tier in plain terms — and matches each one to the drivers and vehicles it actually suits.

What Amperage Actually Means

Amperage measures the rate at which electrical current flows from your charger to your vehicle. Combined with the voltage of a Level 2 charger — 240 volts — it determines output power in kilowatts:

There is one critical constraint: your vehicle’s onboard charger determines the maximum power it will accept, regardless of what the external charger delivers. A vehicle with a 7.2 kW onboard charger will charge at 7.2 kW even when connected to a 40A or 48A unit. Buying a higher-amperage charger than your vehicle can use does not make charging faster — but it does future-proof you for your next vehicle, which may accept higher rates.

The 80 Percent Rule

Before selecting an amperage, you need to understand how it relates to your home’s circuit breakers. Electrical safety standards require that EV chargers draw no more than 80 percent of a circuit breaker’s rated capacity during extended operation.

This means a 16A charger requires a 20-amp breaker. A 32A charger requires a 40-amp breaker. A 40A charger requires a 50-amp breaker — the standard NEMA 14-50 circuit. A 48A charger requires a 60-amp dedicated circuit. If your home’s panel does not currently have the appropriate circuit available, an electrician must add one before the charger can operate at its rated output.

16 Amps: Entry-Level Level 2

A 16-amp charger is a strong match for plug-in hybrid owners whose batteries rarely exceed 20 kWh, and for full EV drivers whose daily commute is well under 50 miles. It operates on any 20-amp circuit, making it the easiest amperage tier to accommodate in homes with limited panel capacity.

The ShockFlo Gmini 16A is available at $159.99 and includes full app control, adjustable output, and IP65 weatherproofing. It is the most accessible Level 2 charger in the ShockFlo range and an appropriate starting point for drivers upgrading from a Level 1 cable for the first time.

32 Amps: The Practical Midpoint

Several popular electric vehicles accept a maximum of 7.2 kW from AC sources: the Nissan LEAF, Volkswagen ID.4, Ford Mustang Mach-E, and Chevrolet Bolt EV all fall into this category. For these vehicles, a 32-amp charger — or the ShockFlo G1 set to its 32A output mode — delivers the maximum speed the vehicle can use. Paying for a higher-amperage charger provides no speed benefit for these models.

40 Amps: The Peak of Portable Performance

Forty amps represents the ceiling for plug-in portable chargers in North America. A NEMA 14-50 outlet runs on a 50-amp circuit, and the 80-percent rule caps the charger’s draw at 40 amps. Achieving higher amperage requires hardwiring.

The ShockFlo G1 40A delivers 9.6 kW — close to or at the maximum onboard charging rate of many contemporary long-range EVs, including the Tesla Model 3 and Model Y, BMW iX, Kia EV6, and Hyundai IONIQ 6. At $189.00, it provides the highest portable Level 2 output available and covers virtually every EV sold today.

48 Amps: Maximum Residential Output

Forty-eight amps is not for everyone — and for most drivers, 40 amps is entirely sufficient. Where 48A delivers meaningful value is for high-mileage drivers who consistently need to recover 150 or more miles of range overnight, for owners of vehicles with onboard chargers rated above 9.6 kW, and for households with two EVs sharing a single overnight charging window.

The ShockFlo S1 supports both 40-amp plug-in use and 48-amp hardwired operation. This makes it uniquely flexible: begin with plug-in charging and upgrade to hardwired when your situation calls for it — without purchasing a new charger.

Quick Selection Guide

Check Your Vehicle Before You Buy

Before selecting a charger, look up your vehicle’s maximum AC onboard charging rate in the owner’s manual or manufacturer specifications. This number — expressed in kilowatts — sets the ceiling for how fast your vehicle can charge regardless of what the external charger provides.

Buying more amperage than your vehicle’s onboard charger accepts does not speed up charging. It does, however, ensure that when you buy a new vehicle with a higher onboard charging rate, your home charger is already capable of meeting it. Buying slightly ahead of your current vehicle is a reasonable hedge — buying dramatically more than you need is not.

Conclusion

For most full battery-electric vehicle owners, the ShockFlo G1 40A covers every reasonable overnight charging scenario at a price that makes the decision easy. Plug-in hybrid owners and low-mileage drivers are well served by the Gmini 16A. High-mileage owners of large-battery EVs who want maximum residential charging performance should consider the ShockFlo S1 48A. For a broader comparison of options, see our best portable Level 2 EV chargers guide.