Overview

The NOCO Boost Plus GB40 is a 1,000-amp lithium jump starter designed for everyday drivers who want emergency starting confidence without a bulky unit taking up trunk space. Weighing just 2.4 pounds and roughly the size of a thick hardcover book, it covers engines up to 6.0L gas and 3.0L diesel — the vast majority of cars, crossovers, SUVs, and half-ton pickup trucks. It’s available on Amazon.com with fast Prime shipping.

What distinguished the GB40 when it launched — and still separates it from cheaper alternatives — is NOCO’s UltraSafe protection system: spark-proof connections and automatic safeguards against short circuits, reverse polarity, and overcharging. Most budget jump starters skip a proper IP rating entirely; the GB40 carries an IP65 certification, meaning it handles dust and low-pressure water jets without issue. That combination of safety engineering and weather resistance, packed into a glovebox-friendly form factor, is why it remains one of Amazon’s best-selling portable jump starters nearly a decade after launch.

Key Specifications

NOCO GB40 Starting Power & Engine Coverage

The GB40’s 1,000-amp peak rating covers a broad swath of passenger vehicles. In TechGearLab’s structured testing of portable jump starters, the GB40 successfully started a 5.7L V8 engine on a cold morning — a real-world scenario that exposes the gap between a unit’s claimed peak amperage and its actual cold-cranking delivery. TechGearLab scored the GB40’s Power Performance at 7 out of 10, noting it performs reliably on most daily drivers but approaches its limits with larger or high-compression engines. With over 100,000 Amazon ratings averaging 4.7 stars, user-reported success with engines ranging from compact four-cylinders to full-size V8 trucks reflects consistent real-world results across diverse conditions.

NOCO’s stated ceiling is 6.0L for gasoline engines and 3.0L for diesel — appropriate coverage for sedans, hatchbacks, crossovers, most mid-size SUVs, and half-ton pickups. Drivers of 3/4-ton or 1-ton diesel trucks (Ram 2500 with the Cummins engine, Ford Super Duty with the Power Stroke, or equivalent) will need to step up to the GB70 (rated to 8.0L gas, 6.0L diesel) or a higher-amperage unit. Per NOCO’s official product documentation, the GB40 delivers up to 20 jump starts on a full charge; in cold temperatures, lithium cells lose a meaningful portion of their available capacity, so it’s worth keeping the unit inside the vehicle when temperatures drop well below freezing rather than leaving it in the trunk.

Safety & Protection Features

Spark-proof connections: NOCO’s UltraSafe clamp system only allows current flow once it detects a proper 12V connection — which means no spark when you first touch the clamp to the battery terminal, unlike conventional jumper cables. This reduces ignition risk from battery off-gassing, a real concern with older or degraded 12V batteries. Reverse polarity protection: Connecting the clamps backwards (red to negative, black to positive) will not damage the GB40 or the vehicle’s electronics — the unit simply won’t deliver power and lights an LED to indicate the error. This is genuinely useful in a nighttime or high-stress roadside situation.

The IP65 rating is the feature that genuinely separates the GB40 from the budget field. Most portable jump starters at the $50–$70 price point have no IP certification at all, meaning rain, a slushy trunk floor, or a condensation-prone storage environment can degrade the unit over time. IP65 certifies dust-tight construction and resistance to sustained low-pressure water jets — protection that matters for something you’re likely to deploy on the side of the road in the rain. TechGearLab’s Durability score of 8 out of 10 for the GB40 reflected this advantage, noting that the housing quality and cable construction exceeded the category average at this price point. A four-stage LED charge indicator is also built in so you can verify the unit is charged at a glance before a long drive.

Portability & Bonus Features

At 7.9 × 3.4 × 1.7 inches and 2.4 lbs, the GB40 fits in a standard glovebox and weighs less than a hardcover novel. The cable connections are tangle-resistant, and the jumper cable insulation stays flexible in cold weather — a detail budget alternatives often cut corners on, with cables that stiffen considerably once temperatures drop. The included storage pouch fits the unit, cables, USB-C charging cable, and manual cleanly.

The USB-A output at 2.1A makes the GB40 a functional emergency power bank — roughly enough capacity for one full phone charge — useful if you’re stranded waiting for roadside assistance. The integrated 100-lumen LED flashlight includes steady, strobe, and SOS modes; the SOS pattern is a small but practical addition for roadside visibility. One ergonomic note: the USB-C charging port is positioned near the clamp connection point, so accessing both simultaneously is slightly awkward if you want to charge the unit with the cables attached.

How Does It Stack Up Against the Competition?

The compact lithium jump starter market is crowded. Here’s how the GB40 compares to three alternatives drivers typically consider at different price points and capability levels.

Is the NOCO Boost Plus GB40 Worth It?

For most drivers — anyone with a car, crossover, SUV, or gasoline half-ton truck — the GB40 is the compact jump starter to buy. Its IP65 weatherproofing, genuinely spark-proof clamps, and reliable real-world performance on engines up to 6.0L give it a safety advantage that alternatives in the $50–$70 range simply can’t match. TechGearLab’s tested scores of 7/10 for power performance and 8/10 for durability — both above the category average — reflect a unit that holds up beyond the first use and performs under actual cold-morning conditions.

The GB40 makes less sense in two scenarios: if you drive a large diesel pickup (3/4-ton or heavier), the GB70 at ~$200 is the right tool; if a built-in tire inflator matters to you, the Schumacher SJ1332 offers 1,200A plus a 150 PSI compressor for about $10 less. For anyone who just wants a reliable, weatherproof jump starter that fits in the glovebox and is ready when needed, the GB40 sets the benchmark for its class.

Marcus WebbSenior Editor 𝕏

Marcus has been hunting for the best tech and gear for over 40 years — as a coder, gamer, and lifelong outdoors enthusiast, he knows the gap between a good spec sheet and something that actually holds up. He brings that same critical eye to everything we cover.

Content produced with AI-assisted research — editorial policy →