40 Amp vs 48 Amp EV Chargers

A 40 amp EV charger is enough when it replaces your daily driving energy within your charging window; choose 48A when your car accepts the extra power and finishing sooner matters. Our default pick is the Emporia Classic in your car's connector, offering up to 40A plug-in, with 9.6 kW at 240V, or 48A hardwired, with 11.5 kW, according to its installation manual.

• 9.6 kWEmporia Classic at 40A and 240V, per its manual
• 11.5 kWEmporia Classic at 48A and 240V, per its manual

Quick picks: choose the job before the charger

Compare specifications and all conditions

J1772 car; want scheduling and either connection format

Our choice

Emporia Classic J1772

What to select

NEMA 14-50 for up to 40A, or hardwired for up to 48A

NACS car; want the same flexibility

Our choice

Emporia Classic NACS

What to select

Select the supply connection separately from the vehicle connector

J1772 car; want simple charging without an app

Our choice

Grizzl-E Classic

What to select

Non-connected Classic, NEMA 14-50, up to 40A

Prefer the ChargePoint app for home and public charging

Our choice

ChargePoint Home Flex alternative

What to select

Match connector and supply format; 48A requires hardwiring

Full comparison table ↔

Swipe to compare. Row labels stay visible.

Your situation	Our choice	What to select
J1772 car; want scheduling and either connection format	Emporia Classic J1772	NEMA 14-50 for up to 40A, or hardwired for up to 48A
NACS car; want the same flexibility	Emporia Classic NACS	Select the supply connection separately from the vehicle connector
J1772 car; want simple charging without an app	Grizzl-E Classic	Non-connected Classic, NEMA 14-50, up to 40A
Prefer the ChargePoint app for home and public charging	ChargePoint Home Flex alternative	Match connector and supply format; 48A requires hardwiring

Your situation	Our choice	What to select
J1772 car; want scheduling and either connection format	Emporia Classic J1772	NEMA 14-50 for up to 40A, or hardwired for up to 48A
NACS car; want the same flexibility	Emporia Classic NACS	Select the supply connection separately from the vehicle connector
J1772 car; want simple charging without an app	Grizzl-E Classic	Non-connected Classic, NEMA 14-50, up to 40A
Prefer the ChargePoint app for home and public charging	ChargePoint Home Flex alternative	Match connector and supply format; 48A requires hardwiring

The Emporia checklist, Grizzl-E specifications and ChargePoint configurations support these choices. The recommendations below are based on published specifications, not physical testing.

40A vs 48A: the useful comparison

These are manufacturer-specific installation limits, drawn from the Classic manual and Home Flex installation guide. They are not a fresh verification of every jurisdiction's electrical code. Hardwired chargers need a licensed electrician and a permit where required.

The arithmetic is kW = volts × amps ÷ 1,000. At equal voltage, 48 ÷ 40 = 1.2: about 20% more power, but only about one-sixth less time for the same energy. That gain disappears if the car or a managed supply holds both options below the lower ceiling.

Check the exact vehicle's maximum AC or Level 2 input, including its model year and trim. Its DC fast-charging rating answers a different question: the DOE distinguishes AC Level 2 from DC fast charging. For example, a hypothetical car capped at 7.7 kW AC gets at most that power from either option. ChargePoint explicitly identifies the onboard charger's rating as a charging-speed limit.

Voltage matters too. For a 208V supply, Emporia lists 8.3kW at 40A and 10kW at 48A. Ask which voltage applies before using the residential worksheet below.

The overnight worksheet: daily miles, winter and a short window

Size for the energy you need to replace before departure, rather than a full empty-to-full battery recharge every night. Start with wall energy recorded across representative driving days, with similar battery charge levels at the beginning and end.

1. 1

   Find the car's AC ceiling

   Read the exact vehicle manual; use the lower of that ceiling and the installer's approved charger output.

2. 2

   Estimate energy to replace

   Daily miles × wall kWh per 100 miles ÷ 100. Use your own charging records where possible.

3. 3

   Compare with your real window

   Wall kWh ÷ available kW gives estimated hours. Count the hours when charging is actually permitted and leave spare time.

The EPA label explainer defines consumption in kWh per 100 miles. Our examples assume 30 wall kWh per 100 miles for ordinary use and 40 for winter use. These are illustrative inputs, not ratings for a particular car or a universal winter penalty. They already include charging losses and accessory energy; do not add another loss allowance to this table. If starting with battery-side consumption instead, account for charging losses once.

Every row assumes 240V, a vehicle accepting at least 11.5 kW AC, uninterrupted output at the maker's rounded 9.6 or 11.5 kW, and sufficient energy needed to sustain charging. Times are arithmetic estimates rounded to the nearest minute.

For example, 48 ÷ 9.6 × 60 = 300 minutes. In an assumed eight-hour overnight window, both settings cover every example. With only four and a half hours available after the long winter day, 40A misses the deadline while 48A fits on paper, with little spare time. That is a concrete reason to consider the higher current.

These are energy-replacement estimates, not guaranteed departure times. DOE's energy-flow explainer says charging losses vary with the vehicle, charging system, battery state and weather. Use your actual cold-weather records and allow extra time for preconditioning or interruptions rather than assuming this winter scenario describes your car.

Decision rule: calculate required average power as wall kWh ÷ available hours. If it is comfortably below the usable 40A rate, choose on installation suitability and features. If it falls between the usable rates, 48A can change the result. If it exceeds both, plan a longer window, another charging opportunity or a different daily energy target.

Best configurable J1772 choice: Emporia Classic

Choose the Classic J1772 when you want app scheduling and a charger family available with either supply connection. Its manual specifies 40A through NEMA 14-50 or 48A hardwired; the 25-foot cable and NEMA Type 4 indoor/outdoor enclosure apply to the family. Emporia's comparison page states UL certification, while its compliance information identifies UL 2594 for the charger.

Select the supply variant deliberately. This card identifies the J1772 family; confirm the selected plug-in or hardwired package before checkout. Emporia's manual supports lower configured currents too, so a hardwired unit need not operate at its maximum. Smart scheduling requires the Emporia app and Wi-Fi, per that manual.

Best configurable NACS choice: Emporia Classic NACS

Choose the NACS Classic for a matching vehicle inlet. Emporia offers both J1772 and NACS, and its checklist gives the same 40A plug-in / 48A hardwired limits. Its UL-certified family and cable specifications are the same ones cited above.

NACS names the car end; NEMA 14-50 names the wall connection. Choose both independently. If considering an adapter, verify Level 2 AC compatibility, its current rating and approval for the equipment; our NACS and J1772 guide explains the directions.

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Best app-free 40A choice: Grizzl-E Classic

Choose the non-connected Grizzl-E Classic if you want straightforward J1772 charging. Its manual states 40A continuous, 9.6 kW, UL listing, and support for a NEMA 14-50 plug. It also permits hardwiring, but that does not raise its maximum to 48A.

There are two source conflicts to resolve before buying. The product page advertises connected features in generic copy but identifies this Classic's smart function as “No Internet Connection.” It also lists a 25-foot cable, while the manual specifies 24 feet for the GR1-14-24 model family. Confirm the actual unit's reach and avoid confusing Classic with the separate Classic Connect.

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Alternative for the ChargePoint app: Home Flex

Home Flex suits buyers who prefer ChargePoint's combined home/public app. Its datasheet lists UL and cUL listing, a 23-foot cable, and output choices of 16, 24, 32, 40, 48 or 50A. That 50A headline does not describe its plug-in output: NEMA versions stop at 40A.

For J1772, distinguish CPH50-NEMA14-50-L23-K, CPH50-NEMA6-50-L23-K and CPH50-HARDWIRE-L23-K. The datasheet assigns those codes to different supply configurations; its hardwired version supports the 48A setting with the approved installation. NACS versions are separate choices. See the Home Flex variant guide and choose on ChargePoint's site.

Panel capacity and the electrician's decision

A spare breaker position does not establish available charging capacity. ChargePoint requires matching the configured current to available panel capacity and identifies charging as a continuous load, requiring circuit capacity of 125% of maximum load. Its manual's 50A → 40A and 60A → 48A pairings explain the different numbers on the charger and circuit.

Ask a licensed electrician:

• What current can this home support, and is load management useful?
• Is the existing receptacle and circuit suitable for this exact charger?
• Which connection format, protection, permits and inspection apply locally?
• Will the cable reach the parked car without tension, including outdoors?
• What charging rate remains available when household demand rises?

Emporia PowerSmart reduces charging when household consumption rises and restores it as capacity returns. Classic needs the monitor and paid software upgrade; Pro bundles the monitor and software. That can make a managed installation worth discussing, but the worksheet must then reflect reduced output and the configured fallback rate. Our Emporia family guide covers the packages.

Black Friday and Cyber Monday: compare the exact configuration

Before treating any offer as a good buy, match the vehicle connector, supply connection, configured current, cable reach and included load-management equipment. Compare the complete installed proposal against your worksheet, rather than selecting by the largest amperage in a family name. Check current purchase terms on the day; this guide makes no sale or discount claim.

How we choose

We compared official manuals, specification tables and support pages, checked on November 2, 2026. Choices prioritize a useful charging rate, matching connectors, stated safety listings and clearly identified installation variants. Calculations use disclosed assumptions, with source conflicts shown beside the affected product. We have not physically tested these chargers.

For broader choices, see our Level 2 charger guide; for charging cords, see portable EV chargers. thisWATT is reader-supported: when you buy through our links, we may earn a commission at no extra cost to you. As an Amazon Associate, thisWATT earns from qualifying purchases.

Verdict

Choose 40A when your worksheet finishes comfortably before departure. Choose 48A when your car accepts it and the shorter charging time earns its place in the installation. Start with Emporia Classic in the matching vehicle connector, pick Grizzl-E Classic for app-free charging, or consider Home Flex for the ChargePoint app. Settle the supply variant and approved current with your electrician before ordering.