16 A, 32 A or 40 A: portable charger amperage

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Portable chargers are sold on amperage, and buyers reasonably assume more is better. It is -- up to the point where the outlet, the car or the circuit becomes the limit, which for most people happens sooner than the spec sheet suggests.

What each tier delivers

Look at the right-hand column before deciding you need 40 A. A typical EV uses somewhere around 10 to 15 kWh for a 40-mile day. Every tier in that table covers it overnight.

The rule that caps all of them

This is why portable chargers are adjustable, and why the adjustment matters more than the headline number. Plugging a 40 A unit into a 30 A dryer circuit without turning it down is the one genuinely dangerous mistake in this category. Charging from a dryer outlet.

Three things that override the spec

• Your car's onboard charger. If it accepts 32 A, a 40 A unit delivers 32 A. How many amps you need.
• The outlet you will actually use, which on the road is rarely the best one.
• Heat. Cheap units and long thin cables both run warmer at the top of their range.

Which tier to buy

The three picks below cover the practical range: a 32 A unit with a 21 ft cable, a 40 A unit with interchangeable plugs, and a dual-voltage 40 A unit that also works on a household socket.

The three tiers

32 A, 40 A, and a dual-voltage unit that covers 120 V and 240 V.

1. Travel and rentals

Lectron portable Level 2 charger

Lectron · J1772 · 32 A / 7.7 kW · 21 ft cable

A plug-in portable that runs at Level 2 speed from a NEMA 14-50 and drops to a standard wall outlet with the included adapter. The travel unit, not the garage unit.

What is good

• +Level 2 speed from a NEMA 14-50 without an installed charger
• +Falls back to a standard household outlet with the adapter
• +Small enough to keep in the trunk

What is not

• −32 A ceiling, meaningfully slower than a 48 A wall unit
• −Not weather-rated for permanent outdoor mounting
• −Repeated plugging and unplugging wears a NEMA 14-50 receptacle faster than a hardwired unit

Published specifications for the Lectron portable Level 2 charger

Maximum output	32 A / 7.7 kW at 240 V
Connector	SAE J1772
Plug	NEMA 14-50, with an adapter for a standard outlet
Use	Portable. Lives in the car, not on the wall

Skip this if: Skip it if this is your only charger and you have a garage. A wall unit is faster and does not live in your trunk.

Specifications above are the manufacturer’s published figures. Source: Lectron. We have not tested this unit — see how we pick.

$269.99 · View on Amazon#ad how we are funded · price as of September 27, 2026

2. The best portable overall

J40A

J+ Booster 2

J+ Americas · J1772 · 40 A / 9.6 kW · 25 ft cable

A 40 A portable in a military-grade aluminum body, ETL certified to UL standards and IP67 rated, weighing 2.2 lb without cables. The portable that behaves like a wall unit.

What is good

• +40 A, matching many wall-mounted units
• +Eight amperage settings from 6 A to 40 A, so it fits almost any outlet
• +Adapters for a wide range of outlets, including NEMA TT-30 for campgrounds
• +IP67 and drive-over resistant, which portables usually are not
• +2.2 lb without cables, so it genuinely travels

What is not

• −Costs more than most portables, and more than some wall units
• −Every extra outlet adapter is a separate purchase
• −Still a portable, so it is not rated for permanent outdoor mounting

Published specifications for the J+ Booster 2

Maximum output	40 A / 9.6 kW at 240 V
Adjustable	6, 8, 12, 16, 20, 24, 32 or 40 A
Power range	1.4 kW to 9.6 kW
Connector	SAE J1772
Cable	21 ft or 25 ft, depending on version
Adapters included	NEMA 14-50 and 5-15
Further adapters available	5-20, 6-15, 6-20, 6-50, TT-30
Weight	2.2 lb without cables; 7 lb with cables and adapters
Body	Military-grade aluminum, drive-over resistant to 6,600 lb wheel loads
Rating	IP67 waterproof and dustproof
Certification	ETL certified to UL standards

Skip this if: Skip it if you only ever charge in one place. A hardwired wall unit is cheaper for a fixed installation.

Specifications above are the manufacturer’s published figures. Source: J+ Americas. We have not tested this unit — see how we pick.

Check price on Amazon#ad how we are funded

3. Level 1 and Level 2 in one

L40A

Lectron Portable Level 1 & 2 Tesla NACS EV Charger

Lectron · NACS · 40 A / 9.6 kW · 20 ft cable

One NACS portable for a standard outlet and a 14-50: 8 to 12 A on 120 V, 16 to 40 A on 240 V, with switchable plugs. The most flexible single unit for a Tesla on the move.

What is good

• +Runs from a standard outlet and a 14-50 with the same unit
• +Adjustable current, so it can be turned down for a weaker circuit
• +Published UL 2594 / UL 2231 certification

What is not

• −NACS only -- a J1772 car needs an adapter
• −On 120 V it is still Level 1: about 5 miles of range per hour at best
• −20 ft of cable, per Lectron's FAQ -- measure the run before relying on it

Published specifications for the Lectron Portable Level 1 & 2 Tesla NACS EV Charger

Level 1 (120 V)	8 to 12 A / 0.96 to 1.44 kW
Level 2 (240 V)	16 to 40 A / 3.84 to 9.6 kW
Connector	NACS (Tesla)
Plugs	Switchable NEMA 5-15 and NEMA 14-50
Cable	20 ft, per Lectron's product FAQ
Certification	UL 2594 / UL 2231, per Lectron

Skip this if: Skip it if a non-Tesla might use it -- it is NACS only -- or if you will only ever charge on 240 V.

Specifications above are the manufacturer’s published figures. Source: Lectron. We have not tested this unit — see how we pick.

Check price on Amazon#ad how we are funded