NOCO Boost Plus GB40 Jump Starter review
By Tom Calder
A well-built, pocketable jump starter that does exactly what it promises for most family cars, with genuine safety touches (spark-proof clamps, reverse-polarity protection) rather than just a big amp number on the box. Like any lithium pack, keep it somewhere temperate — NOCO's own figures put charging at 0–40°C, and a car left in full sun on a hot day can get well past that, so a glovebox or an indoor shelf is a safer home than a parcel shelf or boot over summer.
- Best for
- A compact glovebox backup that gets a flat petrol car or small diesel going without waiting for a breakdown van.
- Skip it if
- You drive a large diesel, van or 4x4 over about 3.0L
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.We earn a commission if you buy through the retailer links on this page. It doesn't change our verdict. How we make money →
Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Small and light (about 1kg) enough to live permanently in a glovebox or door pocket
- Spark-proof clamps and reverse-polarity protection make it safe for non-mechanics to use, even in the dark
- Doubles as a USB power bank and 100-lumen LED torch with an SOS mode, and holds charge for months between top-ups
Worth knowing
- 1000A is a peak/marketing figure, not true cranking amps — real-world coverage is petrol engines up to about 6.0L and diesels up to about 3.0L
- Buying secondhand? Older stock recharges via the slower micro-USB rather than the USB-C port current units ship with
ⓘ As an Amazon Associate, PreparedBritain earns from qualifying purchases. We may earn a commission when you buy, or a fee when you request a quote, through our links. When two products are close, commission can decide which one we pick. A clearly better product always wins. Amazon prices come from Amazon's own product data and show the date and time they were retrieved. Prices at other retailers are checked by us, less often. Prices and stock can change at any time, so always check the retailer's price before you buy.
Our review
The GB40 is NOCO's smallest Boost: a 24 Wh lithium pack under a kilogram with its clamps, built to start petrol engines up to 6 litres and diesels up to 3 litres. It is the size that actually stays in a glovebox, and its protections make it hard to connect wrongly. Bigger diesels need a bigger pack.
What it is
NOCO's data sheet gives a 24 Wh lithium-ion battery, 0.74 kg for the unit and 1.08 kg with clamps, and a body of 196 by 80 by 43 mm. It is rated for 12-volt lead-acid batteries only, and NOCO says it is designed for petrol engines up to 6 litres and diesel engines up to 3 litres, with up to 20 jump starts on a charge. NOCO also says a full pack can recharge a smartphone up to four times, which is a useful extra if you are waiting at the roadside for help with a flat phone as well as a flat battery. The housing is IP65 with the ports closed.
It doubles as a USB power bank, with 5V 2.1A in and out, and has a 100-lumen torch with seven modes including SOS and strobe. Recharging takes about three hours from a 2A USB supply, six hours at 1A or 12 hours at 0.5A.
Safety, and the override
In normal use the clamps are spark-proof and the pack won't send power if they are on the wrong terminals. It detects batteries down to 2 volts. Below that you can hold the button for three seconds to enter Manual Override, and NOCO's guide is blunt: it disables the spark-proof and reverse polarity protection, uses up to 1,000 amps, and should not be attempted if you are unsure. NOCO also says using it voids the warranty.
The guide limits you to five attempts within 15 minutes, then a 15-minute rest, and says never to jump a damaged or frozen battery. Our jump-starting guide walks through the order of connection.
Where to keep it
NOCO rates it to work from −20 to +50°C but to charge only between 0 and +40°C, and its user guide says to store it indoors when not in use. A car parked in July sun can pass those numbers, so a glovebox in winter and a hall cupboard in a heatwave is the sensible routine. Top it up every few months; our car emergency kit checklist puts it alongside the rest of a boot kit.
How it compares
On the comparison, NOCO's GB70 covers petrol to 8 litres and diesel to 6 litres from a 56 Wh pack listed at 1.9 kg. The Boost+Air AX65 adds a tyre inflator. The GB40 is the lightest NOCO here and the one to pick for a small or medium petrol car.
Our verdict
Buy it for a family petrol car or a small diesel, where its size means it is with you when the battery dies. Skip it if you drive a large diesel, a van or a 4x4 over 3 litres: step up to the GB70. NOCO's warranty is one year, so register the pack when it arrives.
A researched review, built from the maker's specs, manual and UK listings; facts checked 2 Nov 2026. Sources: NOCO GB40 data sheet (PDF); NOCO GB40 user guide (PDF); NOCO GB40 support and warranty.
Who shouldn't buy this
Don't buy it if you drive a large diesel, van or 4x4 over about 3.0L — step up to NOCO's bigger GB50/GB70, which carry the amperage this model doesn't.
Key specs
| Peak current | 1000A peak |
| Engine coverage | Petrol ≤6.0L · diesel ≤3.0L |
| Capacity | 12V, 24Wh lithium-ion |
| Extras | IP65 (ports closed) |
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
If this isn’t the one
Best for Drivers who need to cover a bigger diesel - a van, 4x4 or larger family car - as well as ordinary petrol cars, in a pack that still fits in a glovebox.
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Drivers who want one mid-size jump starter that covers most family cars and small diesels, rather than buying NOCO's biggest (and priciest) unit just in case.
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Households with a bigger petrol car, 4x4, van or light diesel, who want one unit that both starts the car and doubles as a genuinely useful USB-C power bank.
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Questions
What size engine will the NOCO GB40 start?
NOCO says it is designed for petrol engines up to 6 litres and diesel engines up to 3 litres, on 12-volt lead-acid batteries only.
How many jump starts does the GB40 give on one charge?
NOCO quotes up to 20. Its guide limits you to five attempts in 15 minutes before a 15-minute rest.
Can I leave the GB40 in the car?
NOCO's guide says to store it indoors when not in use, and it should only be charged between 0 and 40°C. A glovebox is fine in cool weather; bring it indoors in hot spells.
What is Manual Override on the NOCO GB40?
A mode for batteries too flat to detect. It turns off the spark-proof and reverse polarity protection, and NOCO says using it voids the warranty. Only use it if you are confident of the connections.
Free alerts for your home
Home Alerts emails you when a power cut, a Met Office warning or a flood warning covers your postcode. Free for your own home. Sign up in a minute.
Start free →