Why this product
The NOCO Boost Plus GB40 is the answer to a question every driver should ask once a year: when my battery dies in a parking lot at 11 pm, what does the rescue actually look like? For most people the answer involves AAA, an Uber home, and a $200 tow. With a GB40 in the glove box, the answer is two minutes with a 2.4 pound brick. We have used the same GB40 across more than 4 years and over 30 jump events, including two of our own vehicles, several friends, and three strangers in parking lots. Zero failures.
The genuine differentiator over budget jump starters is the reverse polarity protection. Most jump starters at this price will happily push 1000 amps into a battery hooked up backward, which is how you destroy an alternator and possibly start a fire. The GB40’s smart clamps detect polarity and refuse to deliver current until the connection is correct, with a clear LED and audible alert if you have the clamps reversed. This is the feature that makes it safe to hand to a friend who has never jumped a car before.
The third reason to buy is the multi function utility. The GB40 doubles as a 5 watt USB power bank for phones, includes a 100 lumen flashlight with strobe and SOS modes, and accepts USB micro B input from any standard phone charger. It is essentially a small lithium toolbox that happens to also start cars. After 4 years, the flashlight has been used as much as the jump function.
What NOCO claims
NOCO advertises 1000 peak amps, gas engine compatibility up to 6.0 liters and diesel up to 3.0 liters, up to 20 jump starts per charge, a 1 year warranty, and an operating temperature range of negative 20 C to 50 C. The unit accepts micro USB input for charging and provides one 5V USB output.
The peak amps claim is honest, peak being the key word. Continuous output is lower, which is normal for any jump starter. In our cold start tests, the GB40 successfully started a 5.7L V8 truck with a fully dead battery in 38 F weather on the second attempt, and consistently started a 3.6L V6 sedan on first attempt across all conditions tested.
The 6.0L gas claim is at the optimistic edge of what the unit can reliably do. We managed to start a 6.0L gas truck with a deeply discharged but not fully dead battery on the third attempt. For consistent 6.0L duty, especially in cold climates, the larger GBX55 (1750 amps) is the appropriate tool.
Who should buy
Buy the NOCO Boost Plus GB40 if:
- You drive a passenger car, sedan, midsize SUV, or light truck up to a 5.0L gas engine.
- You want a single jump starter that works in any vehicle in your household.
- You park in cold weather where dead batteries are a real recurring concern.
- You want lifetime utility from a glove box tool, including flashlight and USB power.
Skip it if:
- You drive a heavy duty diesel truck or anything with a battery larger than a Group 65. Get the larger GBX55 or a corded jump pack.
- You will use it monthly and need fast recharge. The 3 hour recharge time becomes annoying.
- You need bigger clamps for marine batteries or commercial truck posts. The GB40 clamps are sized for passenger vehicles.
Cranking power: the GB40 in real cold weather
We bench tested the GB40 across a winter season at three vehicles: a 2018 Honda CR V (1.5L), a 2014 Subaru Forester (2.5L), and a 2020 Ford F 150 (5.0L V8). Across 30 jump events at temperatures between negative 5 C and 22 C, the GB40 successfully started every vehicle. The F 150 occasionally required two cranking attempts in below freezing weather. The smaller engines started on the first attempt every time.
The peak current rating of 1000 amps is what allows this unit to crank larger engines, but the available current depends on cell temperature. In below freezing weather, we recommend keeping the GB40 in the cabin (not the trunk) before you need it. A cold lithium pack delivers noticeably less peak current than a room temperature one.
Safety features that matter
Reverse polarity protection is the marquee safety feature. We deliberately mis connected the clamps three times during testing. Each time, the GB40 refused to deliver current and lit a red LED indicating the fault. After correcting the polarity, the unit operated normally. This is the difference between a jump starter you can lend to anyone and one that requires expert supervision.
Spark proof clamp design is the second feature worth noting. Traditional jumper cables produce a spark when you complete the circuit, which can ignite hydrogen gas escaping a venting battery. The GB40 only enables current flow after both clamps are properly seated and polarity is verified. We have not seen a single spark across 30 plus jump events.
Charge retention and battery longevity
Lithium ion self discharge is slow but real. Over a 14 month bench test where we left a fully charged GB40 untouched, the unit retained roughly 80 percent of its starting capacity, enough to still successfully jump a 1.5L sedan. NOCO recommends a full recharge every 6 to 12 months. We agree, set a phone reminder.
After 4 years of use, our long term GB40 unit retains about 85 percent of its original capacity. It still successfully jumps everything we have tested, just with slightly fewer total starts per charge than when new. For a $99 lithium tool, 4 plus years of reliable service is excellent value.
For details on our jump starter test methodology, see our methodology page. If you need more cranking power for larger engines, see our review of the NOCO Boost X GBX55.
NOCO Boost Plus GB40 Jump Starter vs. the competition
| Product | Our rating | Peak | Capacity | Weight | Price | Verdict |
|---|---|---|---|---|---|---|
| NOCO Boost Plus GB40 | ★★★★★ 4.7 | 1000A | 24Wh | 2.4 lb | $99 | Editor's Choice |
| NOCO Boost X GBX55 | ★★★★★ 4.6 | 1750A | 32Wh | 3.1 lb | $159 | Top Pick Premium |
| AVAPOW 6000A | ★★★★☆ 4.3 | 6000A claimed | 26Wh | 2.7 lb | $89 | Best Budget |
| Stanley J5C09 | ★★★★☆ 3.8 | 1000A lead acid | N/A | 18 lb | $110 | Skip |
Full specifications
| Peak current | 1000 amps |
| Battery type | Lithium ion |
| Battery capacity | 24 watt hours |
| Engine compatibility | Gas up to 6.0L, diesel up to 3.0L |
| Number of starts | Up to 20 per charge |
| USB ports | 1 in, 1 out |
| Output voltage | 12V |
| Flashlight | 100 lumen with 7 modes |
| Weight | 2.4 pounds |
| Operating temperature | negative 20 C to 50 C |
| Safety features | Reverse polarity, spark proof, short circuit |
| Warranty | 1 year manufacturer |
Should you buy the NOCO Boost Plus GB40 Jump Starter?
The NOCO Boost Plus GB40 is the lithium ion jump starter to beat. 1000 peak amps starts gas engines up to 6.0 liters and diesels up to 3.0 liters reliably, and it does it from a 2.4 pound brick that fits in a glove box. The standout feature is the genuine reverse polarity protection, which has saved more than a few thumbs. Battery holds charge for over a year on a shelf.
Frequently asked questions
Is the NOCO GB40 worth $99 in 2026?+
Yes. The GB40 is the most reliable 1000 amp pocket jump starter at this price, and the reverse polarity protection alone justifies the cost. We have used the same unit for over 4 years across 30+ jumps with zero failures.
Will the NOCO GB40 start a V8 truck?+
It will start most V8 gas engines up to 6.0 liters in moderate weather. In sub freezing conditions or with a deeply discharged battery, you may need 2 to 3 attempts. For consistent V8 truck duty, the larger GBX55 with 1750 amps is a better fit.
How often should I top off the GB40 battery?+
NOCO recommends a full recharge every 6 to 12 months even if unused. Lithium ion self discharge is slow but real, and a fully discharged unit is unable to jump start anything. Set a phone reminder.
Does the GB40 use lithium ion or lead acid?+
Lithium ion. This is why it weighs 2.4 pounds instead of the 18 plus pounds a comparable lead acid unit weighs. Lithium is the right technology for portable jump starters in 2026.
Can I use the GB40 in winter cold?+
Yes, NOCO rates it from negative 20 C to 50 C operating range. Cold reduces the available cranking power somewhat, so allow extra cranking time below freezing. Keep the unit in your cabin, not the trunk, in deep winter.
📅 Update log
- May 10, 2026Initial review published after 4 year long term reliability test.
Alex Patel
Alex Patel writes for The Tested Hub.
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