NOCO Boost Plus GB40 Review (2026): Verdict

Quick compare — the GB40 against the three alternatives on the makers’ own published facts. We route on engine ratings, not peak amps: peak figures are each brand’s own brief-maximum claim with no shared test behind them. The GB40’s capacity line carries its documentation note in full — see the spec list in its product block.

The category home for this review is our portable jump starters section. If your battery dies repeatedly rather than once, a jump pack is the wrong first purchase — read why batteries drain and what draws them down and our battery guide before you buy anything.

How to choose: judging the NOCO GB40 against the field

A single-product review still needs the buying criteria, because the GB40 only makes sense against them. These are the six checks we applied to it — and the same checks to run on any pack in our pillar jump starter guide before you spend.

Maker engine ratings, not headline amps

NOCO rates the GB40 to 6.0L gas and 3.0L diesel, and those two numbers — not its 1,000A peak headline — decide whether it fits your vehicle. Peak amps are a brief-maximum claim with no shared test standard behind them for any brand, which is why a 4,000A rival is not automatically four times the starter. Work from the litre rating for your fuel, keep headroom where you can, and treat an engine sitting exactly at the ceiling as a reason to step up, not a pass.

Capacity and the watt-hour paperwork

Reserve is what turns one start into several. NOCO’s sell sheet gives the GB40 a 24 Wh lithium-ion pack; the manual excerpt we checked for our pillar guide does not state a watt-hour figure at all, so this review prints the 24 Wh figure attributed to the sell sheet and says so wherever it appears. That is the honest way to read it: a documented maker figure, one step weaker than a manual figure — and still more paperwork than some rivals publish for packs twice its size.

Recharge discipline: the Micro-USB reality

The GB40’s clearest age marker is its Micro-USB input at 5V/2.1A. It refills slowly, on a connector most phone kits have retired, and a pack that takes all evening to refill is a pack that gets left at half charge. The GBX45 alternative answers with 60W USB-C and a maker-stated 48-minute full recharge. Neither fact disqualifies the GB40 — it asks you to be the owner who tops up after every use and checks the pack on the same calendar as our maintenance checklist.

Clamps, override and cold mornings

The GB40’s UltraSafe clamps are spark-proof and reverse-polarity protected, so a tired driver connecting in the dark gets a refusal, not a spark shower. Its manual override matters just as much: a battery flat enough to fall below detection voltage defeats packs that insist on sensing the battery first, and the override is the documented way past that. Owner reports below add the cold caveat — effectiveness falls as temperature drops, and some households store the pack indoors in winter rather than in a frozen glovebox.

Size and weight — two documented figures

NOCO publishes the GB40 at 1.65 lb for the unit alone and 2.4 lb with clamps and accessories, at 6.7 by 3.2 by 1.7 inches. Both figures are documented; they are different weighings, not rival claims. Judge the carry on the with-clamps figure, because that is what rides in the car: light enough for a glovebox or a motorcycle tail bag in a way the 6 lb GB150 alternative never will be — the same carry-the-rated-tool logic we use for portable 12V gear.

Warranty and documentation depth

The GB40 carries a published 1-year limited warranty in its Amazon item details, an IP65 housing rating with ports closed, a stated operating range of -20C to +50C and a charging range of 0C to +40C. None of that is exciting, and all of it is the point: after a long production run, this pack’s paperwork is complete enough that a buyer can check every claim in this review against a maker document. Where a figure could not be traced that way, this review labels its source instead of asserting it.

What the NOCO GB40 is rated to cover, by vehicle class

The GB40’s maker ratings are stated by fuel: gas engines to 6.0L and diesel engines to 3.0L. The table translates those ratings into vehicle classes. It is a rating table, not a promise — a worn starter, corroded terminals or a battery with a dead cell can defeat any pack, and an engine at the ceiling leaves no headroom.

Drivers sizing other 12V equipment will recognise the discipline: rate for the real load and keep headroom where you can — the same rule behind what size winch do I need, how many amps a 12V load draws and how long a battery sustains a load.

Jump starters by budget tier: where the GB40 sits

No prices appear in this review, by site rule: check the live listing on each button, and treat the tier as a statement about format and paperwork, not a promise about what a sale is doing this week. Our affiliate disclosure explains how those buttons work.

Types of portable jump starter in this review

The lead-acid shop format is not a pick here: it trades portability for reserve, and is compared in full in our pillar jump starter guide.

Detailed review: the NOCO Boost Plus GB40 in full

One product gets the full Section 7 treatment below: the NOCO Boost Plus GB40. The three alternatives are summarised after it, each with its own button, and all four meet again in the spec comparison table.

Reviewed: NOCO Boost Plus GB40 — the documented compact

Compact Pick — best for one car or SUV, carried permanently

Why the NOCO GB40 is our pick

The GB40 wins on fit and paperwork, not force. Most dead-battery mornings involve a mainstream gas engine, a battery that is flat rather than destroyed, and a driver who wants the pack back in the glovebox afterwards. A 1,000A pack rated to 6.0L gas and 3.0L diesel, light enough to carry permanently, with clamps that protect a first-time user from their own mistakes, is exactly that shape — and its long production run means its limits are documented by owners, not discovered by them.

Two documentation notes run through this block, because they decide how its figures should be read. Its capacity — 24 Wh — comes from NOCO’s sell sheet; the manual excerpt checked for our pillar guide states no watt-hour figure, so the spec list attributes it every time. And its weight is published two ways: 1.65 lb for the unit alone, 2.4 lb with clamps and accessories. Both are maker figures for different weighings, and this review prints both rather than quietly choosing the flattering one.

NOCO GB40 key specs

• Model: GB40 (part number GB40; ASIN B015TKUPIC; UPC 046221150025)
• Peak current: 1,000A (NOCO sell sheet and Amazon manufacturer chart)
• Maker engine rating: Gas up to 6.0L; diesel up to 3.0L
• Starts per charge: Up to 20 (maker figure)
• Internal battery: Lithium-ion, 24 Wh per the NOCO sell sheet — the manual excerpt checked does not state a Wh figure
• Charging input: Micro-USB, 5V/2.1A
• USB output: 5V, 2.1A — a phone top-up port, not a laptop supply
• Light and safety: 100-lumen LED, 7 modes; spark-proof connections, reverse-polarity protection, manual override for batteries below 2V
• Housing: IP65 with ports closed
• Temperature range: Operating -20C to +50C; charging 0C to +40C (manual)
• Weight and size: 1.65 lb unit alone; 2.4 lb with clamps and accessories; 6.7 x 3.2 x 1.7 in
• Warranty: 1-year limited (Amazon item details)

NOCO GB40: fits and best for

Cars, crossovers and SUVs with gas engines to 6.0L, small diesels to 3.0L, and small 12V machines — motorcycles, ATVs and mowers — well inside its ratings. It fits best as the permanent pack for a single-vehicle household, a teen driver’s first car, a partner’s car that is never the project vehicle, or a second car that sits between uses. Households sizing recovery gear in Jeep picks or truck winch picks will find the same pattern: the rated, carried tool beats the oversized one left at home.

NOCO GB40 pros and watch-outs

NOCO GB40: what owners report

NOCO GB40: who should not buy

Do not buy the GB40 if your diesel runs past 3.0L or your gas V8 sits past 6.0L — it is below the maker rating for your engine, and no override mode changes a rating. Start instead with the NOCO Boost Pro GB150, rated to 7.0L diesel, and size from the diesel column only. Our pillar guide shows where every pack in this class stops.

NOCO GB40: pair it with

Pair it with the case NOCO makes for it. The NOCO GBC013 is an EVA protection case listed for the GB20 and GB40, so the reviewed pack here is an exact fit, not a near fit: a glovebox pack lives loose among tools, cables and tyre irons, and a case is what keeps its ports clean and its clamps untangled for the morning it is needed. Storage protection is the same habit as a winch cover — the tool you protect is the tool that works.

Check Price — NOCO GBC013 case for GB40

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The alternatives in brief

NOCO Boost X GBX45 — the fast refill

Rated to 6.5L gas and 4.0L diesel, with 60W USB-C Power Delivery in and out, a maker-stated 48-minute full recharge and a jump-ready charge in about five minutes, at 1.30 lb for the unit. Its paperwork carries one open conflict: NOCO’s own regional listings disagree on starts per charge — up to 6 in the US listing, up to 8 in the UK listing — and we print the conflict rather than picking a winner. Choose it when charging discipline, not engine size, is your failure mode, and when the pack should also charge modern devices properly.

Check Price on Amazon

NOCO Boost Pro GB150 — the big-engine NOCO

Rated to 9.0L gas and 7.0L diesel on the current Amazon manufacturer table — figures that supersede the older 8.5L and 6.5L numbers still circulating — with up to 80 starts, an 88 Wh pack on its datasheet, a 500-lumen light and a 12V XGC port, at 6 lb for the unit. A JL Wrangler Forums owner validated one starting a Jeep with a dead auxiliary battery quickly after an overnight charge. Choose it when the GB40’s diesel ceiling is the whole problem and you accept trunk weight as the price of headroom.

Check Price on Amazon

GOOLOO GT4000S — the screen and the ratings

GOOLOO rates it to 12.0L gas and 10.0L diesel with up to 60 starts claimed, 100W two-way USB-C, a 3.2-inch status screen and a 400-lumen light. Its paperwork has its own conflicts, printed here as documented: the Amazon item details for this unit say 20,000 mAh while other reproductions vary, so no watt-hour figure is asserted, and its warranty prints as 18 months from the Amazon manufacturer description against 2 years in some reproductions. Owner reports are mixed — faultless diesel and equipment starts alongside GT-line charging complaints, and one nearly dead 5.3L V8 it would not crank where a smaller NOCO did. Choose it when you want the display and the ratings and accept GOOLOO’s documentation style.

Check Price on Amazon

Spec comparison: NOCO GB40 vs the alternatives

Read the attributed cells as information: the GB40’s sell-sheet capacity note and the GBX45’s split starts figure mark where maker documents disagree with each other, and this table prints the disagreement instead of resolving it quietly. The full field, including the lead-acid shop format this review leaves out, is compared in our best portable jump starter guide.

Using the NOCO GB40: procedure and fitment notes

There is no installation — the fitment is the connection. Connect the GB40’s clamps to the vehicle battery, positive to positive and negative to the battery’s negative terminal, with the pack switched off while you work. Its clamps are spark-proof and reverse-polarity protected: connect them the wrong way round and the pack refuses rather than sparking, which is the protection that matters at night, in rain, with a queue forming behind you. Switch the pack on, start the engine, then switch the pack off and remove the clamps promptly once the engine is running.

The completely-flat case is what the manual override is for. A battery drained below the voltage the clamps need to detect can leave a smart pack silent even when it is fully charged; the GB40’s override lets you direct it to deliver a start anyway, per its manual. Because the override deliberately bypasses the detection that normally protects you, confirm the clamp polarity by eye before you use it, and treat it as a last step, never a first one. Twin-battery diesels are past this pack’s diesel rating in most cases — follow the vehicle maker’s own jump procedure and buy the rated pack instead. If the engine only clicks, work through clicks-but-no-crank diagnosis — the logic of a click, a weak connection and a dead cell is the same — and keep battery health ahead of pack size when a vehicle eats batteries.

Safety essentials

NOCO GBC013 EVA protection case — listed for the GB20 and GB40, so it is the exact-fit case for the pack under review: ports stay clean, clamps stay untangled, and the glovebox stops being an abrasion test. See our accessories section for how it sits in a vehicle kit.

Check Price — NOCO GBC013 case

NOCO GENIUS5 smart charger and maintainer — the fix for the repeat-drain pattern: a 5A 6V/12V charger, maintainer and desulfator that keeps a parked vehicle’s battery full instead of rescuing it monthly. It is the honest first purchase behind essential vehicle accessories for any vehicle that sits.

Check Price — NOCO GENIUS5

Energizer jumper cables, 16-foot, 6-gauge (ENB-616U) — the donor-vehicle backup for the day the pack is flat, lent out, or beaten by a battery with a dead cell; a carrying bag is included. Cables are the analogue insurance in our recovery kit guide too: simple, shared and always compatible.

Check Price — Energizer jumper cables

Troubleshooting

Most rows trace back to storage and connection, not starting power. Our maintenance checklist approach — inspect and top up on a calendar — is the whole fix, and safe 12V procedure basics covers the same discipline for the rest of the kit.

Who should NOT buy the NOCO GB40

Diesel truck owners past 3.0L. The GB40’s diesel ceiling excludes most diesel pickups outright, and an override mode does not extend a maker rating. Buy the GB150 alternative for its 7.0L diesel rating or the GT4000S for 10.0L, and size from the diesel column only — the error this review exists to prevent is a compact pack bought on its gas headline for a diesel truck, the same undersizing we warn against in diesel truck gear.

Owners of a vehicle that sits for weeks. If your battery is flat every time you return to the car, the battery is being damaged by repeated deep discharge and a maintainer is the purchase — a jump pack treats the symptom while the battery dies slowly. Start with the GENIUS5 above, and diagnose the drain with our battery-drain guide.

Drivers who need fast refills and modern device power. Micro-USB in and a single 5V/2.1A USB out were ordinary when this pack launched and are slow now. If the pack must refill in under an hour and charge a laptop-class device, the GBX45 alternative — 60W USB-C in both directions — is the honest buy, and its slightly larger ratings come with it.

Shops, fleets and anyone starting vehicles all day. Twenty starts per charge on maker figures, in a glovebox format, is occasional-duty equipment. Repeated daily starts belong to the lead-acid shop format compared in our pillar guide — reserve and cable reach over portability — or to the GB150’s larger reserve among the lithium picks here.

Anyone replacing a battery that has already failed. A pack that starts a vehicle with a dead cell has postponed a stranding, not prevented one. If jump starts are becoming weekly, spend on the battery first — our battery guide — and let the pack go back to being an emergency tool.

Final verdict

Reviewed pick — NOCO Boost Plus GB40: the documented compact standard for one car or SUV, bought for its paperwork, its override clamps and its permanent-carry size. Check its price.

Fast-charge alternative — NOCO Boost X GBX45: the pack for owners whose real risk is a flat pack and a dead phone, not a big engine. Check its price.

Big-engine alternative — NOCO Boost Pro GB150: NOCO’s own answer when the GB40’s diesel ceiling is the problem. Check its price.

Screen alternative — GOOLOO GT4000S: the strongest published ratings with a display, for big-engine and diesel drivers who want the pack to report itself. Check its price.

FAQ

Is the NOCO Boost Plus GB40 worth buying?

For its intended owner, yes: one car, crossover or SUV with a gas engine up to 6.0L, carried permanently and used occasionally. You are buying complete published paperwork, protective clamps with a manual override, IP65 sealing and a long owner record, in the lightest format in this review. It is not worth it for a diesel truck past 3.0L, for daily shop duty, or if slow Micro-USB recharging will leave it flat — the alternatives in this review serve each of those buyers better.

What engines does the NOCO GB40 cover?

On NOCO’s maker ratings, gas engines up to 6.0L and diesel engines up to 3.0L, across 12V vehicles. Those are maker ratings, not test results, and they assume a healthy starter, clean terminals and a fully charged pack. Treat both ceilings as limits rather than targets: a 6.2L gas V8 is past the gas rating, and a diesel sitting exactly at 3.0L leaves no headroom, so drivers at either edge should buy the larger alternative instead.

How many starts does the GB40 give per charge?

NOCO’s published figure is up to 20 starts per charge. Read it as a maker maximum under favourable conditions, not a promise for your worst morning: a very flat battery, repeated long cranks and deep cold all spend reserve faster, and owner reports in this review describe effectiveness falling as temperature drops. The practical rule is the one in our safety section — recharge after every use, so the next start never depends on remembering how many are left.

What does the GB40 manual override do?

It lets the pack deliver a start when the vehicle battery has fallen below the voltage its smart clamps need to detect — the completely-flat case where a protected pack would otherwise sit silent. Per the GB40 manual, you confirm the clamp polarity by eye and then direct the pack to start anyway. Because the override bypasses the detection that normally protects you, it is a last step after checking the connections, never the first thing to try.

How often does the NOCO GB40 need recharging?

After every use, and on a calendar check in storage. Lithium packs self-discharge slowly, but slowly is not never: owner discussions in this review include NOCO packs needing a storage top-up every three to four months. The GB40 charges over Micro-USB at 5V/2.1A, so a full refill is an overnight habit rather than a coffee-break one — put the check on the same reminder as your other vehicle checks and the pack will be ready when the battery is not.

Can the GB40 start a diesel truck?

Only a small one. Its maker diesel rating stops at 3.0L, which covers diesel cars and small diesel SUVs and excludes the 6.6L and 6.7L engines in heavy-duty pickups by a wide margin. Diesel engines crank harder than gas engines of the same size, which is why every pack in this review carries a diesel rating well below its gas rating. Diesel truck owners should buy the GB150, rated to 7.0L diesel, or the GT4000S, rated to 10.0L.

NOCO GB40 vs GBX45: which should I buy?

Buy the GB40 for the lightest carry, the longest owner record and the lower-friction glovebox role, and accept Micro-USB charging. Buy the GBX45 if your real failure mode is a pack that is flat when needed: its 60W USB-C input refills it in a maker-stated 48 minutes, it charges modern devices properly, and its ratings step up slightly to 6.5L gas and 4.0L diesel. Its one paperwork wrinkle is a starts-per-charge conflict between NOCO’s US and UK listings, printed in full in the comparison tables.

Is the GB40’s 24 Wh capacity figure reliable?

It is a documented maker figure with a labelled source, which is the most this review claims for it. The 24 Wh figure comes from NOCO’s sell sheet; the GB40 manual excerpt we checked for our pillar guide does not state a watt-hour figure at all. We print the attribution wherever the figure appears so you can weigh it correctly — stronger than a retailer’s unsourced number, one step weaker than a manual specification.

Will the GB40 work in winter?

Within its published operating range of -20C to +50C, yes — with the honest caveat owners repeat: lithium output and a cold battery’s cranking strength both fall as temperature drops, so a winter start spends more of the pack than a summer one. Owners in the Bogleheads thread report keeping the pack indoors in winter rather than in a frozen car. If sub-zero starts on a large engine are your routine case rather than your emergency, buy headroom — a bigger pack is the winter answer, not a warmer glovebox alone.

Sources & changelog

Maker and listing sources: NOCO GB40 Amazon listing — item details, part number, UPC and warranty; NOCO GB40 manual record at manuals.plus — operating and charging ranges, override procedure; NOCO GB40 sell sheet figures (24 Wh, unit and with-clamps weights) as recorded in our research pools; NOCO GBX45 Amazon listing; NOCO GB150 Amazon listing and its datasheet record via a fulfilled-by-Amazon retailer reproduction; GOOLOO GT4000S Amazon listing, GOOLOO GT4000S product page and its maker-spec reproduction. Accessory verification: camelcamelcamel record for the NOCO GBC013 case.

Owner sources: Bogleheads — booster-pack owner thread; IH8MUD — lithium jump-starter thread, including the GB40 counter-report; HDForums — jump-starter owner thread; AR15.com — GOOLOO or NOCO owner verdict thread and its GT4000 and GT4000S owner thread; JL Wrangler Forums — GB150 owner validation thread; BobIsTheOilGuy — high-performance jumper starters; AutoGuide — best portable car jump starters.

Changelog — October 18, 2026: guide first published.

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