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NOCO GB40 buying guide
NOCO GB40: what it starts, and when to step up to the GBX45 or GB50
NOCO rates the Boost Plus GB40 at 1,000 amps peak for 12-volt lead-acid batteries, gas engines up to 6.0 liters and diesel engines up to 3.0 liters, with up to 20 jump starts per charge. If your diesel is bigger than 3.0 liters, or your gas engine is over 6.0, NOCO's GBX45 (6.5 L gas, 4.0 L diesel) and GB50 (7.0 L gas, 4.5 L diesel) are the next steps up.
Linked option: if your engine is within the GB40's rating, this is the listing we checked. Check the NOCO Boost GB40 on Amazon
Prepared from NOCO's product and tech-spec pages for the GB40, GBX45 and GB50, read October 10, 2026. We have not tested these packs. All ratings are NOCO's own. The GB40 link goes to an Amazon listing checked on October 10, 2026 as new, sold by Amazon.com and in stock; offers change, so check that the listing says GB40. The GBX45 and GB50 are not linked because we have not confirmed Amazon offers for them.
Will the GB40 start my engine?
Check two numbers on your vehicle: engine size and fuel. NOCO's GB40 rating covers gas engines up to 6.0 liters and diesel engines up to 3.0 liters, on 12-volt lead-acid batteries. NOCO says it is designed for a car, boat, RV, truck and more within those limits.
- Gas up to 6.0 L, diesel up to 3.0 L: within the GB40's rating.
- Gas 6.0 to 6.5 L, or diesel 3.0 to 4.0 L: outside the GB40's rating; NOCO rates the GBX45 for these.
- Gas 6.5 to 7.0 L, or diesel 4.0 to 4.5 L: NOCO rates the GB50 for these.
- Anything that is not a 12-volt lead-acid battery: NOCO's spec pages for all three list 12 Volt Lead-Acid Batteries as the battery type.
GB40, GBX45 or GB50
| What you compare | GB40 | GBX45 | GB50 |
|---|---|---|---|
| Peak current | 1,000 A | 1,250 A | 1,500 A |
| Gas / diesel engines | Up to 6.0 L / 3.0 L | Up to 6.5 L / 4.0 L | Up to 7.0 L / 4.5 L |
| Jump starts per charge | Up to 20 | Not stated on the pages read | Up to 30 |
| Internal battery | 24 Wh | 31 Wh | 35 Wh |
| Recharging the pack | USB-C, 5 V 2.1 A max; 3 hours at 2.1 A | USB-C Power Delivery up to 60 W; full recharge in 48 minutes with a compatible charger | USB-C, 5 V 2.1 A max; 3 hours at 2.1 A |
| Charging your devices | 5 V 2.1 A | USB-A 10 W; USB-C up to 60 W (phones, tablets, laptops) | 5 V 2.1 A |
| Flashlight | 100 lumens, seven modes | 100 lumens | 200 lumens, seven modes |
| Weight | 2.45 lb (spec page; overview says 2.4) | 2.16 lb | 2.71 lb (spec page; overview says 2.7) |
| Water resistance / warranty | IP65 (the user guide adds: with ports closed) / 1 year | IP65 with ports closed / 1 year | IP65 / 1 year |
The GBX45 is NOCO's Boost X model: it adds fast USB-C Power Delivery charging in both directions and a 60-second start window after you press the power button. NOCO says it can go from empty to a jump start after 5 minutes of charging. The GB40 and GB50 recharge from a powered USB port at 2.1 amps. For the GBX45's manual limits and box contents, see our NOCO GBX45 guide; for other brands, see our jump starter guides.
Limits in the GB40 user guide
- Battery type: 12-volt lead-acid batteries only; the guide says not to use it with any other type of battery. NOCO's data sheet lists wet, gel, MF, EFB and AGM lead-acid batteries.
- Very flat batteries: it is designed to jump start batteries down to 2 volts. Below that, the guide describes a manual override mode and warns that it disables all safety measures.
- Repeated attempts: some vehicles need the GB40 connected for up to 30 seconds; if the engine does not start, wait 20 to 30 seconds. No more than five consecutive jump starts within 15 minutes, then let it rest for 15 minutes.
- Temperature: operating range -4°F to 122°F (-20°C to 50°C); charging range 32°F to 104°F (0°C to 40°C). Do not jump start a frozen battery.
- Recharging: NOCO's data sheet charts about 3 hours at 2 amps, 6 hours at 1 amp and 12 hours at 0.5 amps.
- Storage: the guide says to store it indoors, not outdoors, and not to leave it charging for more than a week at a time.
Those limits are NOCO's; read the full guide before your first use.
What comes in the GB40 box
NOCO lists the GB40 jump starter, heavy-duty precision battery clamps, a USB-C to USB-C cable, a microfiber storage bag and safety and warranty information. No wall charger is listed. The guide says it can be recharged from any powered USB port, such as an AC adapter, car charger or laptop, and arrives partly charged, so charge it fully before first use.
When to skip the GB40
- Skip it for diesel engines over 3.0 liters; NOCO's rating stops there.
- Skip it if you want to recharge a laptop from the pack or recharge the pack in under an hour; NOCO lists those for the GBX45, not the GB40.
- Skip it for batteries other than 12-volt lead-acid; that is the only battery type NOCO lists.
Sources
- NOCO pages: GB40 overview, GB40 tech specs, GB40 user guide and GB40 data sheet; GBX45 overview and specs; GB50 overview and specs. All read October 10, 2026.