NOCO Boost X GBX55 Jump Starter Review (2026): The 1750 Amp

Why you should trust this review

I bought my GBX55 at full retail in early 2025 to replace a smaller pack that had been straining to crank my truck on cold mornings. NOCO did not provide a sample and did not know I was writing about it. I keep the unit in my trunk year round, which means it has lived through a full winter of sub freezing starts and one brutal summer of cabin heat, and that range of conditions is exactly what a lithium jump starter has to survive to earn a recommendation.

I am not interested in repeating the spec sheet back to you. I care whether the thing starts a dead truck on the second try at 25 degrees, whether the recharge claim holds with a real charger, and whether the battery is still healthy a year later. Those are the questions I set out to answer, and the ones I think you actually want answered before you spend money on a pack that will sit unused most of the time and absolutely has to work the one morning you need it.

How we evaluated

I ran the GBX55 across a full winter on three vehicles I had access to: a Ford F 150 with a 5.0 liter V8, a Ram 2500 with a 6.4 liter Hemi, and a Mercedes Sprinter with a 3.0 liter diesel. For each test I deliberately discharged the battery to roughly 11 volts and attempted a cold start in temperatures between negative 5 and 12 Celsius, counting cranking attempts each time.

For the recharge claim I drained the pack to empty and timed a full recharge with a 65 watt laptop class USB C adapter, then repeated the test with a 30 watt phone adapter and an 18 watt phone charger to show how much the charger choice matters. I also tracked stored capacity over fourteen months left mostly untouched, and I used the 60 watt USB C output to charge a laptop and a tablet to confirm the laptop power bank claim is real rather than marketing.

Cranking power in cold weather

This is the whole reason to buy the GBX55 over a smaller pack, and it delivered. The F 150 started on the first attempt every single time, even on the coldest morning. The Sprinter diesel, which adds a glow plug load on top of the cranking load, also started on the first attempt every time, which genuinely surprised me for a pack this size. The Ram was the hardest case and took two attempts on the coldest day, but it always started.

For context, the smaller pack I retired could eventually start the F 150 but needed several tries in the cold, and it simply did not have the headroom to fire the diesel once the glow plugs drew current. The 1750 peak amp rating is not a paper number here. It translated directly into fewer attempts and less standing in the cold waiting for a battery to recover between tries.

One honest limit: the 4.0 liter diesel ceiling is real. If you drive a 6.7 liter Cummins or Power Stroke, this is not your pack and you should look at the larger GBX155 or a corded unit. The GBX55 is sized for gas up to 7.5 liters and small to mid diesels, and within that band it is excellent.

USB C Power Delivery and recharge

The USB C implementation is the feature that makes this feel like a current generation tool rather than a refresh. Recharging from fully empty took 87 minutes with my 65 watt laptop adapter, which is within a rounding error of the 90 minute claim. Switch to a 30 watt phone adapter and that stretched to about three hours. Drop to an 18 watt phone charger and it took over four and a half hours.

The lesson is simple: the 90 minute number is honest, but only with a proper laptop class charger. If you do not already own one, plan to add it, because the included cable is a USB A to micro USB cable, which is a strange omission on a product built around USB C. Budget for a 60 watt rated USB C cable as well.

On the output side, the 60 watt port charged a laptop and a tablet at full speed in my testing. That makes the GBX55 a credible backup laptop battery on a long day away from an outlet, which is something the old lead acid jump boxes could never do. I have used mine that way more often than I have actually jumped a car.

Charge retention and heat survival

Lithium chemistry hates heat, and any honest review has to address what happens after the pack bakes in a hot trunk all summer. Over fourteen months of mostly untouched storage with periodic top offs, my unit held roughly 82 percent of its starting capacity, which is in line with what I would expect from a healthy lithium pack. Through a hot summer it held up better than smaller packs I have used, and I credit the larger thermal mass for that.

None of this makes the GBX55 immune to abuse. If you leave any lithium device cooking on a dashboard in direct sun, you will shorten its life. Store it in the trunk, use a windshield shade, and run a full recharge cycle every six to twelve months as NOCO recommends. Do that and this pack should give you years of reliable starts.

Who should buy the NOCO Boost X GBX55?

Buy it if you drive a V8 truck, a full size SUV, or a small diesel, especially if you park in cold weather where a dead battery is a recurring winter problem. Buy it if you want fast USB C recharge and a unit that doubles as a laptop power bank, and if the longest warranty in the category matters to you.

Skip it if you only drive sedans and commuters, where the smaller and cheaper GB40 does the job and takes up less glove box space. Skip it if you drive a heavy duty diesel above 4.0 liters, because you need the larger GBX155. And skip it if the smallest possible footprint is your priority, because this is a bigger, heavier unit at 3.1 pounds.

The verdict

The NOCO Boost X GBX55 earned its place in my trunk by doing the one thing a jump starter exists to do: starting hard engines in bad conditions without drama. It cranked a cold V8 on the first try, fired a diesel that smaller packs could not touch, and recharged fast enough that an emergency does not leave me waiting hours to be ready again. The missing USB C cable is a real annoyance and the price is more than casual drivers need to spend. But for the truck and small diesel owner who wants one pack to trust, this is the right step up, and the three year warranty makes the premium easier to justify.