Liters Not Amps product guide
NOCO Boost GB40 1000A 12V Lithium Jump Starter
Gas engines to 6.0L and diesels to 3.0L on 12V lead-acid
NOCO rates the GB40 at 1000 peak amps for gas engines up to 6.0 litres and diesels up to 3.0 litres, on a 24 Wh lithium pack. It is spark-proof and reverse-polarity protected in normal use — but the manual override that starts a battery below 2 volts switches both of those off.
Listing checked . Confirm the model, included parts and availability before ordering.
Published specifications
- NOCO: 1000 A peak; gas up to 6.0 L, diesel up to 3.0 L; 12V lead-acid only
- NOCO: 24 Wh lithium-ion internal battery; USB in and out at 5V 2.1A
- Guide: recharge about 3 h at 2 A, 6 h at 1 A, 12 h at 0.5 A
- Guide: no more than 5 consecutive starts in 15 minutes, then rest 15 minutes
- Guide: operate -20°C to +50°C; charge 0°C to +40°C; store -20°C to +50°C
- NOCO: 1-year limited warranty, non-transferable; claim terms differ by guide version
Fit and limits
Strengths
- Spark-proof and reverse-polarity protection in normal use, plus an IP65 housing
- Starts 12V lead-acid batteries down to 2 volts without the override
- NOCO publishes full specs, engine ratings and the complete warranty text
Caveats
- Manual override disables both safety protections and can push up to 1000 amps
- Guide limits you to five starts in fifteen minutes, then a fifteen-minute rest
- Warranty is non-transferable, and the two guide versions state different claim steps
What NOCO rates it for, and what is in the box
The GB40 is rated by NOCO at 1000 amps peak. Its tech specs page states a gas engine rating of up to 6.0 litres and a diesel engine rating of up to 3.0 litres, and the overview page adds up to 20 jump starts on a charge. Those are the maker's own figures for this model; the Amazon listing repeats them. Use them as a ceiling, not a promise for a particular cold morning.
The specs page lists an internal 24 watt-hour lithium-ion battery, a 100-lumen LED with seven light modes, an IP65 rating and a product size of 7.72 inches wide, 3.16 high and 1.71 deep at 2.45 pounds. The guide's own specification page gives 6.7 by 3.2 by 1.7 inches and 2.4 pounds, so the two maker documents do not match on length and weight; Amazon's table gives a third set of numbers again.
NOCO's box list is the GB40, heavy-duty precision battery clamps, a USB-C to USB-C cable, a microfiber storage bag and safety and warranty information. Amazon's included-components field matches. There is no wall adapter in either list.
The compatibility rule is narrower than the vehicle list suggests
The guide is emphatic on one point: the GB40 is for 12-volt lead-acid batteries only. It says not to use it with any other type of battery, that jump starting other chemistries may cause injury, death or property damage, and that you should contact the battery maker first and not attempt a jump start if you are unsure of the battery's chemistry or voltage.
It also asks you to read the vehicle owner's manual for that car's own jump-starting precautions before connecting, and not to make connections to the carburettor, fuel lines or thin sheet metal. Its written procedure is for negative-ground systems, with the order reversed for the uncommon positive-ground case: clamps to the 12V OUT port first, then red to positive, then black to negative or chassis, and disconnect in reverse.
Before starting, the guide says to turn off the vehicle's power loads — headlights, radio, air conditioning. Most vehicles start immediately, some need the GB40 connected for up to 30 seconds, and if it does not start you should wait 20 to 30 seconds and try again.
Five starts in fifteen minutes, then it rests
This is the duty rule and it is easy to miss. The guide says not to attempt more than five consecutive jump starts within a fifteen-minute period, and to allow the GB40 to rest for fifteen minutes before trying again. If you are dealing with a car that needs repeated cranking, that limit will arrive before the battery capacity does.
Heat has its own signal. The Error LED blinking red with the cables connected properly means the internal battery is too hot, and the fix listed is to let the unit cool and move it somewhere cooler. A solid red Error LED means reverse polarity, cleared by reversing the connections. If the Boost light does not come on with the cables connected properly, the guide says the battery is below 2 volts.
The guide also says not to leave the product unattended while in use, not to cover it, and not to jump start a damaged or frozen battery. Cooling is by natural convection, with no fan.
Manual override: what it turns off
The GB40 normally detects the battery and enters Boost mode by itself, and it is designed to jump start 12-volt lead-acid batteries down to 2 volts. Below 2 volts the Boost LED stays off because the unit cannot detect a battery at all. Manual Override, enabled by holding its button for three seconds, forces the jump-start function on.
The guide's caution about that mode is printed in capitals and deserves reading before you need it. Both the spark-proof and reverse-polarity protection features are disabled. It tells you to pay very close attention to polarity, not to let the positive and negative clamps touch or connect to each other because the product will generate sparks, and that the mode uses very high current, up to 1000 amps, which can cause sparks and high heat if not used properly. Its closing line is that if you are unsure about using this mode, do not attempt it and seek professional help.
In normal operation the protections the maker names are spark-proof connections and reverse-polarity protection, and the enclosure is rated IP65 with the ports closed. Override is the exception to both, which is precisely why it exists as a separate held button rather than an ordinary setting.
Recharging, and a port difference between the two maker documents
The guide's recharge table is straightforward: about 12 hours from a 0.5-amp source, 6 hours at 1 amp, and 3 hours at 2 amps. Amazon's bullet quotes the 3-hour figure alone. The unit comes partially charged and the guide says to charge it fully before first use, and that it can be recharged from any powered USB port — an AC adapter, car charger or laptop. Because of FCC regulations, NOCO recommends not charging and discharging at the same time.
The two maker documents do not describe the same port. The listing-supplied guide's specification page lists a Micro USB input at 5V 2.1A, while NOCO's current tech specs page lists a USB-C input at 5 volts 2.1 amps max, and both NOCO's box list and the Amazon bullets say a USB-C cable is supplied. Check which socket is on the unit you actually receive before buying a replacement cable.
On chargers, the guide asks for the included cable with a NOCO 10W 12V adapter, or a third-party 5W or 10W adapter compliant with one of several named standards, and warns that generic adapters may shorten the product's life or cause malfunction. It also says to avoid leaving it charging for more than a week at a time, because overcharging may shorten battery life.
Temperature, storage and the warranty's return condition
The guide specifies an operating range of -20°C to +50°C, a charging range of 0°C to +40°C, and a storage range of -20°C to +50°C with a daily average of 0°C to +25°C, adding that 80°C must never be exceeded under any condition. It says to discontinue use immediately if the battery becomes excessively warm, and not to operate outside the stated ranges.
On keeping it ready, the guide says an unused product will discharge over time and must be recharged before use, and to disconnect it from power sources when not in use. Neither the guide nor NOCO's pages that we read give a specific interval — no 'recharge every three months' figure — so set your own reminder rather than assuming a glovebox unit stays charged.
Both guides give a one-year limited warranty against defects in materials and workmanship, non-transferable, with repair or replacement at NOCO's option, and both exclude accident, abuse, liquid contact, modification, attempted unauthorised repair, cosmetic damage, normal wear, and units with a removed or defaced serial number. The claim procedure differs between the two versions, so read whichever paperwork comes in your box. The copy attached to this listing says you must first obtain an RMA number from NOCO Support and send the product with either the receipt or a warranty fee of 45 percent of MSRP, prepaying packaging and transport. NOCO's current guide dated 03.07.2025 has no RMA or fee clause: it says NOCO will repair, replace or refund at its option, that certain information including proof of purchase is required, and that the warranty does not cover return packaging and transport costs. It also notes the period may extend to a minimum of two years for purchasers in the EU, EFTA and the UK. Either way, keep your receipt, and because the warranty is non-transferable, check the seller and the condition of the offer you select.
Check the current listing
Confirm the model, included parts and availability before ordering.
Primary sources
- NOCO GB40 user guide and warranty, English section (listing-supplied copy)
- NOCO current GB40 user guide, dated 03.07.2025A
- NOCO tech specs page for the GB40 1000A jump starter
- NOCO product overview page for the GB40
Primary sources checked .
Compare with
- NOCO Boost GB20 500A 12V Lithium Jump Starter
Gas engines up to 4.0 litres, motorcycles and powersport
- NOCO Boost X GBX75 2500A 12V Lithium Jump Starter
Gas engines to 8.5L and diesels to 6.5L on 12V lead-acid
- GOOLOO GP4000 4000A 12V Jump Starter
Larger gas and diesel engines, plus 12V accessory power
- GOOLOO A3 3000A Jump Starter with Air Compressor
One glovebox tool for a flat battery and a soft tire
Side-by-side pages, this model next to: NOCO Boost GB20 500A 12V Lithium Jump Starter, NOCO Boost X GBX75 2500A 12V Lithium Jump Starter, GOOLOO GP4000 4000A 12V Jump Starter, GOOLOO A3 3000A Jump Starter with Air Compressor.