NOCO 12V lithium jump starter

A compact jump-starter that earns its glove-box space

The GB40 has lived in my glove box for more than a year, and in that time it’s bailed me and a few neighbors out more than once. It’s compact, clear about what it can (and can’t) do, and—most importantly—puts enough power into a dead battery to get you rolling without fuss. It isn’t perfect, and you should treat it like a consumable rather than a forever tool, but as a first-line emergency starter for most gas vehicles, it’s a strong pick.

Build and design

This is a tidy, brick-sized pack with a rubberized shell that shrugs off scuffs and the occasional splash. It feels sturdier than many no-name packs: the seams are tight, the ports have snug covers, and the clamps are properly chunky rather than toy-like. The included storage bag is basic but useful, and the cables are long enough to reach remote under-hood jump posts on cars with trunk-mounted batteries—something cheaper packs often struggle with.

At about the size of a paperback and light enough to toss into a door pocket, it’s easy to keep on hand. The LED status bar is simple and legible. There’s a built-in flashlight with steady, SOS, and strobe modes, which I’ve actually used to find a decent ground point on a rainy shoulder. The USB-A output turns the unit into a backup battery for phones and headlamps; it won’t replace a dedicated power bank, but it’s handy in a pinch.

Starting performance

Rated at 1000 A peak for 12 V systems and advertised for up to 6.0 L gas and 3.0 L diesel engines, the GB40 punches above its size. Real-world performance is about more than a headline peak number, though: engine displacement, battery health, temperature, and how long the vehicle’s been sitting all matter.

Here’s what I’ve seen:
- Four-cylinder gas sedans and small crossovers: effortless. Even with a battery that was so weak the interior lights barely flickered, the car started on the first crank.
- Mid-size V6 gas engines: no drama. One start after another on a cold morning, with the pack dropping only a single bar.
- Full-size V8 gas truck: started cleanly on a subzero day, though the truck battery wasn’t completely toast. In harsher cases, I’ve needed a second attempt after giving the battery a 30–60 second “pre-charge” with the clamps connected.
- Small diesels (around 3.0 L): workable if the glow plugs aren’t demanding huge current and the battery isn’t utterly flat. As temperatures drop, your margin shrinks; bigger diesel engines should look to a higher-capacity booster.

The “up to 20 starts per charge” claim is optimistic outside mild weather and small engines. In mixed use—one or two real rescues and a handful of test starts—I typically get 6–10 confident starts per full charge. In winter, especially with larger engines, expect fewer. That’s not a knock; it’s just physics in a compact pack.

If your vehicle’s battery is deeply discharged, some jump starters won’t recognize it and refuse to deliver power. The GB40 has a way to handle that scenario. There’s an override procedure described in the manual for batteries that read essentially zero volts. Use it carefully, verify your polarity, and it can mean the difference between a tow and a quick getaway.

Ease of use and safety

Hookup is straightforward: red to positive, black to ground (ideally a clean, unpainted engine or chassis point), power on, and crank within 30 seconds. I appreciate two things here. First, the clamps have strong spring tension and real bite, which helps on corroded or awkward posts. Second, the safety electronics are conservative. The unit won’t energize the leads if it senses you’re reversed, and it’s spark-proof under normal handling. That gives confidence when you’re contorted under a hood in the dark.

A few tips that have made my starts more reliable:
- Make your ground connection to bare metal on the engine or frame, not the negative battery post.
- Clean a small area with the clamp jaws if there’s oxidation—those serrations can scrape enough to help.
- If it doesn’t start on the first try, leave the pack connected for 30–90 seconds to let the car battery absorb a little charge, then try again.
- In extreme cold, bring the GB40 into the cabin for five minutes with the heat on before use; warm lithium chemistry performs better.

Battery life and charging

Lithium jump starters can be misleading about shelf life. The GB40 does hold a charge well in temperate storage; kept indoors, I’ve seen minimal self-discharge over a couple of months. Inside a car through seasonal swings, it will drop faster. I set a reminder to top it off monthly in winter and every 2–3 months in summer. That routine has kept it ready.

Charging is via USB, which is convenient but not fast. Plan on a few hours from low to full on a typical USB wall adapter. If you rely on it frequently—fleet use, multiple family cars—build recharging into your habit right after a jump. The battery is not user-replaceable. Like most compact boosters, treat it as a multi-year tool, not a lifetime one.

Extras that matter (and some that don’t)

• Flashlight: brighter and more useful than I expected for roadside work and battery terminal hunting.
• USB power bank: handy for topping up a phone or headlamp. It’s a quality-of-life bonus, not a reason to buy.
• Water and dust resistance: the housing and port covers help in wet conditions, but don’t leave it out in a downpour or dunk it.
• Storage bag: nothing fancy, but it keeps the clamps from chewing up other gear.

Limitations and quirks

• Warranty and longevity: the one-year warranty is on the short side for a tool many people will stash and forget. I haven’t had a failure, but lithium cells age, and electronic buttons/switches can be single points of failure. If you want something with a longer warranty or a field-replaceable battery, you’ll be looking at different formats and usually larger units.
• Cold-weather margin: it works in subzero temps, but like every lithium pack, capacity drops. Keep it charged and warm it briefly before use when possible.
• Cable length: adequate for most under-hood posts, but if your battery is deeply buried and your jump studs are awkward, you may wish for another few inches.
• Not a miracle worker: if a vehicle’s electrical issue goes beyond a weak battery—bad terminal clamps, failing alternator, or a parasitic draw—the GB40 will get you started, but it won’t cure the problem.

Who it’s for

• Everyday drivers who want a compact, easy-to-use booster that covers most gas cars and small diesels.
• Households with multiple vehicles that occasionally sit for weeks.
• DIYers who value solid clamps, sensible safety features, and a rugged shell without stepping up to a bulky shop unit.

Who should look elsewhere:
- Owners of large diesels or high-compression engines that regularly see deep cold; you’ll want more headroom.
- Users who need a replaceable battery or a longer warranty period.
- Anyone expecting dozens of starts between charges in winter; consider a higher-capacity pack.

Recommendation

I recommend the GB40 as a dependable, glove-box-sized insurance policy for most drivers. It’s compact, thoughtfully built, and strong enough to start typical 4-, 6-, and even many 8-cylinder gas engines, with conservative safety features that make it approachable for first-timers. The flashlight and USB port are welcome extras, the clamps inspire confidence, and the cable length is better than the bargain-bin crowd.

Go in with appropriate expectations: keep it charged, store it sensibly, and understand that the battery inside is a consumable over the course of several years. If you want a jump starter that lives in the car, works across common scenarios—including cold mornings—and doesn’t turn a roadside hiccup into a production, the GB40 is a smart, compact choice. If you need more cranking margin, a longer warranty, or a serviceable battery down the line, step up to a larger format. For everyone else, this one earns its spot.