The Boost Plus GB40 is the default recommendation for most drivers: 1000A is plenty for the engines in the average driveway, the price stays near $100, and NOCO's safety engineering is the most proven in the category. Step up to the GB70 or GBX55 only if you run a large diesel or want USB-C fast charging.
Full review
Real-World Performance
Pro Tool Reviews scored the GB40 a 9.4 out of 10 and described it as 'extremely compact, only 8 inches long and weighs just 2.4 pounds,' noting that after jumping a vehicle twice 'the unit still showed a full charge,' which makes NOCO's claim of up to 20 jumps per charge believable in everyday use. CNN Underscored's lab testing measured the GB40 delivering roughly 160 amps at 7 volts and 100 amps near 10 volts under load, which is modest on paper but enough to crank the four- and six-cylinder engines most drivers own. The 1000A peak rating covers gas engines up to 6.0 liters and diesels up to 3.0 liters, so the typical sedan, crossover and light truck are all comfortably within range.
Where the GB40 shines is consistency and approachability. Reviewers repeatedly describe it starting dead batteries in freezing weather and reviving cars that have sat untouched for weeks, the exact scenarios a jump starter exists for. It is also forgiving: the onboard charge-level indicator and clear error feedback mean a first-time user is not left guessing whether the unit is ready or whether the clamps are seated correctly. That ease of use, more than raw amperage, is why so many reviewers default to recommending it for the average driver who just wants the car to start.
Build Quality and Design
At 2.4 pounds without the clamps and only 8 inches long, the GB40 is the smallest unit in this roundup and the easiest to leave in a glovebox or door pocket. The polycarbonate shell is rated for impact and incidental water spray, and the integrated cables use insulated, spark-proof clamps that feel more substantial than the price suggests. The compact form factor is a deliberate design choice: NOCO built the GB40 to be the unit you actually keep in the car, rather than a heavy box that ends up forgotten on a garage shelf.
NOCO's UltraSafe system is the headline engineering feature: spark-proof connections, reverse-polarity protection and short-circuit prevention mean a distracted or inexperienced user is far less likely to fry car electronics or injure themselves. Reviewers across Pro Tool Reviews and Automoblog repeatedly single out this safety circuitry as the reason the GB40 has become the best-selling jump starter on the market, even as cheaper, higher-amp competitors flood the category. It is the feature that separates the GB40 from no-name boxes that match its peak amps on the spec sheet but lack the protection electronics.
Battery Life and Power
The lithium-ion pack holds enough charge for roughly 20 jump-starts and doubles as a 2.1A USB-A power bank good for several phone recharges, a useful secondary role on a long drive or a campsite. The trade-off is the charging interface: this generation still uses micro-USB input, so a full recharge is slow compared with the USB-C GBX55, and you cannot top it up from a modern USB-C wall charger or laptop brick without an adapter.
Like all lithium jump starters, the GB40 self-discharges in storage and needs a top-up every few months to stay jump-ready. Multiple reviewers note this is the single most common reason a unit appears to 'fail' when an owner finally needs it after a year of neglect, and the GB40 is no exception. Treat it like any emergency tool and charge it on a schedule. The built-in flashlight with seven modes, including strobe and SOS, is a genuinely useful roadside safety extra rather than a token feature, and it draws little enough power that it does not meaningfully eat into jump reserve.
Where It Falls Short
The GB40's 1000A peak is the lowest in this group, and CNN Underscored noted it is 'nearly the lowest-powered in Noco's lineup.' For a large diesel, a V8 truck, or a deeply discharged big battery in extreme cold, you want the 2000A GB70 or the 1750A GBX55 instead, both of which have meaningfully more cranking headroom. The short integrated cables can also make reaching side-post or awkwardly recessed batteries fiddly, and there is no way to extend them.
The micro-USB recharge feels dated next to the GBX55's 60W USB-C, which can go from empty to jump-ready in five minutes; the GB40 simply cannot do an emergency fast top-up. And as a pure power bank it is limited by its small capacity and single USB-A port. None of these are dealbreakers for the target buyer, but collectively they are the reasons NOCO sells three pricier models above it, and the reasons a big-engine or road-trip-focused buyer should look up the range.
Value at This Price
Hovering around $100, the GB40 is the value sweet spot for ordinary drivers. You are paying for NOCO's proven safety circuitry and reliability rather than raw amperage, and for the majority of cars on the road that is exactly the right priority. The unit holds its resale and reputation well, and NOCO's warranty and customer support are among the better in the category.
Cheaper units like the GOOLOO GP2000 offer more peak amps for less money, but with a shorter and more uneven reliability track record, so the GB40 effectively asks you to pay a modest premium for peace of mind. For most buyers that is money well spent. The GB40 is the unit to buy if you want something you can stash and forget, confident it will work the one cold morning you actually need it, rather than the highest number on the box.
Who It's Best For
Buy the GB40 if you drive a sedan, crossover, minivan or small truck and want a compact, trustworthy jump starter for under or around $100. It is ideal as a glovebox emergency tool for a household with one or two ordinary vehicles, and its small size means it actually stays in the car instead of getting left behind. It is also a sensible gift for a new driver who needs something foolproof.
Skip it if you own a large diesel pickup, tow heavy loads, or routinely deal with big, cold, deeply discharged batteries, in which case the 2000A GB70 is the safer call. Skip it too if you want a single device that also serves as a high-capacity laptop power bank or recharges over USB-C, where the GBX55 or the WOLFBOX MegaVolt24 are clearly better suited. For its intended audience, though, the GB40 remains the easiest unit in the category to recommend.
How It Compares to Alternatives
Within this lineup the GB40 is the entry point, and the trade-offs are clear. The GOOLOO GP2000 undercuts it on price and doubles its peak amps on paper, but with far less consistent quality control, so the GB40's modest premium buys reliability. Stepping up, the NOCO Boost X GBX55 adds 60W USB-C fast charging and more cranking power for road-trippers, while the NOCO Boost HD GB70 adds reserve capacity and rugged cabling for big-engine and diesel owners.
The WOLFBOX MegaVolt24 sits at the opposite end of the range with 4000A and a huge battery, aimed at buyers who want one device for everything. Against all of them, the GB40 wins on size, simplicity and price for the ordinary driver, and loses only on the metrics most ordinary drivers do not need. That focus is exactly why it remains NOCO's best-seller and the default recommendation for a first jump starter.
Strengths
- +1000A peak output starts virtually any passenger car, SUV or light truck (up to 6.0L gas / 3.0L diesel)
- +Tiny 8-inch, 2.4 lb body fits a glovebox yet holds roughly 20 jumps per charge
- +UltraSafe spark-proof clamps with reverse-polarity protection prevent the classic jump-start mishaps
- +Doubles as a 2.1A USB-A power bank and built-in flashlight with seven modes
- +Cheapest entry into the NOCO ecosystem and the most popular jump starter sold
Watch-outs
- −Underpowered for large V8 diesels and big trucks that need the GB70 or GBX55
- −Slow micro-USB recharge with no USB-C input on this generation
- −Lithium cells need topping up every few months in storage to stay jump-ready
- −Integrated clamp cables are short, so reaching side-post batteries can be awkward
How it compares
The most compact and affordable pick here. It is outpowered by the 2000A NOCO Boost HD GB70, the 1750A USB-C NOCO Boost X GBX55, and the 4000A WOLFBOX MegaVolt24, but it costs less than all of them and covers the engines most drivers actually own. Only the GOOLOO GP2000 undercuts it on price.
Who this is for
At a glance: everyday drivers of sedans, SUVs and small trucks who want a proven, glovebox-sized jump starter near $100.
Why you’d buy the NOCO Boost Plus GB40
- 1000A peak output starts virtually any passenger car, SUV or light truck (up to 6.0L gas / 3.0L diesel).
- Tiny 8-inch, 2.4 lb body fits a glovebox yet holds roughly 20 jumps per charge.
- UltraSafe spark-proof clamps with reverse-polarity protection prevent the classic jump-start mishaps.
Why you’d skip it
- Underpowered for large V8 diesels and big trucks that need the GB70 or GBX55.
- Slow micro-USB recharge with no USB-C input on this generation.
- Lithium cells need topping up every few months in storage to stay jump-ready.
Rating sources
“The NOCO GB40 Boost Plus jump starter is extremely compact. It's only 8 inches long and weighs just 2.4 pounds.”
“At right around $100, this is a model worth keeping an eye on for those in the market for a portable jump starter.”
“A powerful compact car jump starter that punches well above its size for everyday drivers.”
Our 4.7 score is the average of these published ratings. Ratings marked * were derived from the reviewer’s written analysis or video transcript — the publisher didn’t print an explicit numeric score, so we inferred one from their own words. Click through to verify. More about methodology.
