NOCO Boost Plus GB40 review

Eleven years, and still the answer

The retail listing dates the GB40 to December 2015. In consumer electronics that is close to geological. The phone in your pocket has been replaced five times over; this pack is still on the shelf at close to its original price, and it is still the pick on the jump starter page and referenced on sixteen pages across this site.

That is worth examining rather than assuming. A product that survives a decade unchanged is either genuinely finished, or it is coasting on a reputation the market has quietly moved past. The way to tell is to put it next to what else you can buy today and see where it actually loses.

Where it loses, honestly

Against the packs ranked on best jump starters for cold weather, the GB40 is beaten on nearly every published figure.

Read that row by row and the GB40 looks like a bad buy. It is the weakest headline figure, the shortest commitment, and it is not the cheapest. Two of those three deserve an answer and one of them does not have a good one.

The amp figure, which is the one not to worry about

A sixty-dollar pack publishing three times the peak amps of a hundred-dollar one should make you suspicious rather than impressed. There is no standard governing how a consumer jump-starter peak-amp figure is measured, which is why the numbers in that column are not comparable with each other — a point the cold-weather page sets out in full, including one maker that advertises its figure is measured at the clamps precisely because the industry's usually are not.

The figure that answers your actual question is the engine-size ceiling, and NOCO publishes it plainly: gasoline up to 6.0 liters, diesel up to 3.0. That covers the overwhelming majority of cars on an American road. If your engine is inside it, a bigger peak-amp number buys you nothing at all.

So of the three columns the GB40 loses, one is not a real loss. The other two are.

What it wins on, and why it is the right trade

Every bullet NOCO leads with is about the connection rather than the power. “Patented spark-proof and reverse polarity protection for foolproof connections to any 12V vehicle - no sparks, no wrong connections.”

The rest of what NOCO publishes is consistent with a product built to sit unused for years and then work: an IP65 housing with rubberized over-molding against water, dust and impact; a 100-lumen light with seven modes including SOS, because the other thing you need at the roadside is to be seen; and a 3-hour recharge over USB-C so topping it up is not a chore.

And there is the thing no spec sheet captures: the company is still here. A two-year warranty from a brand that may not exist in eighteen months is worth less than a one-year warranty from one that has been selling the same product since 2015. That is not a figure, and it is the honest reason this pack keeps its place.

Where it is genuinely behind

• Twelve months is the shortest warranty in this category on this site. Hulkman publishes two years on both its packs, AstroAI publishes two, GOOLOO eighteen months. NOCO publishes one, on the most expensive pack of the five. There is no reading of that which favors NOCO, and it is the clearest argument against buying one
• No operating-temperature range is published. On a product most people buy because of winter, NOCO publishes no cold figure at all — where GOOLOO publishes a full -4 F to 140 F range and Hulkman publishes a pre-heat system rated to start at -40 F. The GB40 may well work fine in the cold; NOCO simply does not say so
• The listing cannot agree with itself about the weight. One bullet describes a “compact 2.5 lb form factor” while the listing’s own dimension field reads 0.496 lb. A jump starter is not half a pound. It is a small thing, and it is the kind of small thing that tells you how much weight the rest of that data block can carry
• “Engineered in the USA” is doing careful work. Engineered is not manufactured, and the listing does not say where it is made

One figure this site quotes that could not be re-verified

This site states a battery capacity of 24 Wh for the GB40, and that figure does real work — it is what power bank vs jump starter is built on, and what explains the published “up to 20 starts per charge”.

Checking it for this review, two things turned up. The capacity does not appear on the retail listing at all, which publishes peak amps and starts-per-charge but no watt-hour figure. And NOCO’s own site could not be read: the product URL returns HTTP 403 to an automated request and the alternative paths tried returned 404.

So the 24 Wh is recorded here as what it is — a figure this site has carried from a third-party specification aggregator rather than from NOCO, which could not be confirmed at the maker today. The product record has been updated to say so rather than implying NOCO published it. It is very likely correct; it is not currently verifiable, and this site prefers saying that to quietly keeping the attribution.

Using it, and the habit that decides whether it works

1. Charge it before you need it, on a schedule. A lithium pack sitting in a hot trunk self-discharges, and the morning it matters is not the morning to find out. Twice a year, when the clocks change, is the habit the roundup recommends and it is the single biggest determinant of whether you own a jump starter or a brick
2. Check your engine against the ceiling now, not then. 6.0 L gas, 3.0 L diesel. Diesels need far more cranking current for the same displacement
3. Read the procedure once while it is warm and daylight. How to jump start a car covers the order of operations; doing it for the first time in the dark is how people get it wrong
4. Do not charge it when it is freezing. Charging a lithium cell below freezing damages it permanently — bring it indoors first. NOCO does not print this; AstroAI does, and it applies to every pack in the category
5. Keep it where you can reach it from the driver's seat. Where to store emergency gear covers why the trunk is not always the right answer

Who should buy something else

• Anyone with a diesel over 3.0 L or a big gas engine. The ceiling is a real limit, and the GB50 and GB70 exist for exactly this
• Anyone whose winters are genuinely severe. If the car lives outside somewhere that reaches -20 F, a pack that publishes a cold figure is worth more than one that does not — see the cold-weather page
• Anyone who wants the pack to inflate tires too. That is a different product class — jump starter and inflator combos
• Anyone whose battery is the actual problem. A jump starter rescues; it does not fix. If you are jumping the car more than once, test the battery

The verdict

It stays the recommendation, with the reasoning stated more plainly than before. You are buying the lowest peak-amp figure and the shortest warranty in its category, and getting in exchange an interlock that makes the one dangerous step foolproof, a housing built to survive years of neglect, and a brand that has been selling this exact product since 2015.

For a thing you buy hoping never to use it, the second list matters more than the first. But the twelve-month warranty is a real weakness rather than a quirk, and if two of NOCO’s competitors can publish two years and a cold rating, there is no good reason NOCO cannot.