Can you jump start an electric car?

The confusion here is reasonable, because the word "battery" is doing two jobs. An EV's traction battery is the several-hundred-volt pack under the floor that moves the car; it is charged from a charging station and nothing in a trunk kit interacts with it. Separately, almost every EV also carries a conventional 12-volt battery, and that small, ordinary, unglamorous component is the one that leaves EV owners standing in parking lots.

Because the whole low-voltage side of a car still runs on 12 volts: the body computers, the door locks, the displays, the lights, the horn, and — critically — the contactors that connect the traction battery to everything else. Until those contactors close, the big battery is electrically isolated by design. So the 12-volt battery is what wakes the car up, and if it is flat the car cannot use its own traction battery to help itself. A full traction battery and a dead 12-volt battery is a car that does nothing at all.

That is a genuinely counterintuitive failure, and it is common. A 12-volt battery in an EV leads a slightly odd life: no alternator, charged instead by a DC-DC converter from the traction pack whenever the car decides to, and subject to the same parasitic drains, cold snaps and old age as anyone else's.

On a conventional car the battery is usually the first thing you see when the hood opens. On an EV it may be under a frunk floor panel, behind a cover in the trunk, or accessible only through two designated posts in the front compartment. Several manufacturers route a positive post and a ground stud specifically for this purpose, precisely because they do not want people hunting around a high-voltage vehicle with a clamp.

There is a second-order problem too: if the 12-volt battery is dead, the electrically-released hood or charge-port release may not work, which is exactly the situation the designated external terminals exist to solve. This is the strongest argument on this page for reading your own manual on a dry afternoon rather than in a parking garage. How to use a jump starter covers the order of operations once you have found the posts.

Much less than a gas car, and this is the one piece of good news. There is no engine to turn over. All the pack has to do is bring the 12-volt system up to a voltage where the car's electronics boot and the contactors close, after which the traction battery takes over and recharges the 12-volt battery through the DC-DC converter. That is a small job in current terms.

So the smallest real pack in the range is enough — a 500-amp, 24 watt-hour unit covers it — and the sensible buying criteria become weight, packed size and whether you will actually keep it charged. That makes the GB40 the easy default and the GBX45 the right answer for anyone who travels, because at 2.16 lb and 31 watt-hours it recharges from the same USB-C brick as a laptop and sits well under the 100 watt-hour airline threshold. Flying with a jump starter covers those limits, and the best jump starter for Tesla is the model-specific version of this page.

1. 1Do not try to jump another car from your EV. Several manufacturers explicitly prohibit it. The 12-volt system and its DC-DC converter are not designed to supply hundreds of amps to someone else's starter motor, and the damage is on your side. Use a jump pack for the other car — that is what it is for.
2. 2Do not expect a jump pack to help a flat traction battery. An EV out of charge is a tow or a mobile charging service, not a trunk-kit problem. The two systems are unrelated.
3. 3Do not ignore a 12-volt battery that has died once. EV 12-volt batteries are frequently replaced on a schedule rather than on failure for good reason — when this one goes flat you do not merely lose cranking, you lose the car entirely. How to tell if a car battery is bad is the five-minute test, and a 12-volt battery that has been deeply discharged once is a battery to watch.

1. Best overall for an EV

NOCO Boost Plus GB40

NOCO · Best for most cars and small suvs

The default answer for a four- or six-cylinder car: 1,000 peak amps, 24 watt-hours, and light enough that it actually stays in the trunk.

Published specifications

Peak amps

1,000 A source

Internal battery

24 Wh lithium-ion source

Gas engine rating

Up to 6.0 liters source

Diesel engine rating

Up to 3.0 liters source

Weight

2.45 lb (1.11 kg) source

Water resistance

IP65 source

Flashlight

100 lumens source

Warranty

1-year hassle-free source

What works

• +24 Wh sits far under the 100 Wh carry-on threshold, so flying with it needs no airline approval
• +2.45 lb and pocketable — the size that decides whether a tool is still in the trunk six months later
• +IP65 enclosure, so a wet shoulder in the rain is not a problem
• +Reverse-polarity protection means a backwards clamp does not spark

What does not

• −1,000 peak amps runs out of headroom above a 6.0 L gas engine
• −The 3.0 L diesel ceiling rules out most modern diesel pickups
• −24 Wh is a small reserve — it is a jump starter, not a power bank substitute

Skip it if

Not the one to buy if you drive a diesel pickup or a big V8. You would be at the edge of its rating on a cold morning, which is exactly when you want margin.

$99.95·View on Amazon→

#ad Affiliate link · Price as of October 17, 2026

Raw specifications: NOCO’s own page for the NOCO Boost Plus GB40.

2. Best for an EV that travels

NOCO Boost X GBX45

NOCO · Best for travel and carry-on use

The travel pick: 1,250 peak amps at 2.16 lb with USB-C Power Delivery in and out, so it recharges from the same brick as your laptop.

Published specifications

Peak amps

1,250 A source

Internal battery

31 Wh lithium-ion source

Gas engine rating

Up to 6.5 liters source

Diesel engine rating

Up to 4.0 liters source

Weight

2.16 lb (0.98 kg) source

USB-C output

Up to 20 V / 3 A Power Delivery source

Water resistance

IP65 with ports closed source

Warranty

1-year hassle-free source

What works

• +Lightest pack in the range at 2.16 lb, and 31 Wh means no airline paperwork
• +USB-C Power Delivery both directions — one cable covers the pack, phone and laptop
• +More gas headroom than the GB40 (6.5 L against 6.0 L) in a lighter body

What does not

• −The IP65 rating only holds with the port covers closed — worth remembering in the rain
• −The 4.0 L diesel ceiling is not enough for a full-size diesel pickup

Skip it if

Not the right pack for a diesel truck, and not the cheapest way to cover a small commuter — its premium buys packability, not amps.

$124.95·View on Amazon→

#ad Affiliate link · Price as of October 17, 2026

Raw specifications: NOCO’s own page for the NOCO Boost X GBX45.

3. Smallest pack that does the job

NOCO Boost Sport GB20

NOCO · Best for motorcycles, atvs and small engines

The smallest pack in the range and the right one for powersports: 500 peak amps, 2.1 lb, and a gas rating that stops at 4.0 liters — which is all a bike or a quad ever asks for.

Published specifications

Peak amps

500 A source

Internal battery

24 Wh lithium-ion source

Gas engine rating

Up to 4.0 liters source

Diesel engine rating

Not recommended source

Weight

2.1 lb (0.95 kg) source

Water resistance

IP65 source

Flashlight

100 lumens source

Warranty

1-year hassle-free source

What works

• +2.1 lb — light enough to live under a motorcycle seat or in an ATV storage box, which is the whole point
• +500 peak amps is correctly sized for powersports batteries rather than wildly over them
• +Same IP65 enclosure and reverse-polarity protection as the larger packs
• +24 Wh, so it flies in carry-on baggage like the rest of the range

What does not

• −The 4.0 L gas ceiling rules out most cars, so it is not a do-everything pack
• −NOCO states diesel is not recommended at all for this model — read that as a hard limit
• −Small reserve, so cold-weather attempts eat into it quickly

Skip it if

Do not buy it as your car's pack as well. NOCO's own rating stops at 4.0 L gas and says not recommended for diesel, and a bike pack asked to start a car is exactly the wrong economy.

$79.95·View on Amazon→

#ad Affiliate link · Price as of October 17, 2026

Raw specifications: NOCO’s own page for the NOCO Boost Sport GB20.

If your EV sits for long periods — a second car, a vacation home, a winter where you barely drive — the useful tool is a maintainer rather than a pack, kept on the 12-volt battery if your manual permits it. Check that first: a few manufacturers restrict external charging of the 12-volt battery while the car is connected, and the manual is the only authority on your car. How long can a car sit before the battery dies covers the timescale that matters.