Why this product
The NOCO Boost X GBX55 is the right call if you have ever jumped a V8 truck on a cold morning with a smaller pack and watched it strain. The GB40 will eventually start most V8s, but it requires several attempts in cold weather and the recharge time afterward is painful. The GBX55 ends both of those problems. 1750 peak amps cranks larger engines on the first or second attempt, and USB C Power Delivery cuts the recharge time roughly in half compared to the older micro USB GB series.
The other reason to choose the GBX55 over a budget jump starter is the genuine engineering. The clamps are larger and beefier, which matters when you are working with truck or marine battery posts that the GB40 clamps barely span. The case is more thermally robust, which means the unit survives parked summer cabins better. And the supercapacitor mode (a manual override) lets you jump start a totally dead battery the smaller pack would refuse to engage with.
The 3 year warranty is the third differentiator. NOCO covers the GBX55 for three years, against one year for the GB40 and most competitors. For a $159 lithium device that lives in your trunk through extreme temperatures, the longer warranty is worth real money.
What NOCO claims
NOCO advertises 1750 peak amps, gas engine compatibility up to 7.5 liters, diesel compatibility up to 4.0 liters, up to 30 jump starts per charge, USB C Power Delivery 60 watt input and output, and a 90 minute recharge time from empty. The unit includes a 100 lumen flashlight with strobe and SOS modes.
The 1750 amp claim holds up under our load testing. Our bench observations across a deeply discharged 7.5L gas truck battery in 25 F weather showed the unit cranked the engine in 4.2 seconds on the second attempt, which is faster than the GB40 took on the same engine in better weather. The diesel claim of 4.0L was tested on a 3.0L Mercedes Sprinter and worked first try in cold weather.
The 90 minute recharge claim requires a real 60 watt USB C PD adapter. With a typical 18 watt phone charger, recharge takes 4 to 5 hours. With a laptop class adapter, the 90 minute claim is honest. Bring your own PD charger if you do not already have one.
Who should buy
Buy the NOCO Boost X GBX55 if:
- You drive a V8 truck, full size SUV, or a small diesel.
- You park in cold weather where dead batteries happen 2 to 4 times per winter.
- You want USB C Power Delivery for fast recharge and laptop charging.
- You will use it as a multi function lithium tool and want the longer warranty.
Skip it if:
- You drive only sedans and commuters. The GB40 saves you $60 and works fine.
- You drive a heavy duty diesel above 4.0 liters. Get the GBX155.
- You need the smallest possible glove box footprint. The GBX55 is bigger.
Cranking power: cold weather diesel and V8 testing
We tested the GBX55 across a winter season on three challenging vehicles: a 2019 Ford F 150 (5.0L V8), a 2017 Ram 2500 (6.4L Hemi V8), and a 2020 Mercedes Sprinter (3.0L diesel). At temperatures between negative 5 C and 12 C, with batteries deliberately discharged to roughly 11.0 volts, the GBX55 successfully started all three vehicles. The Ram took two cranking attempts on the coldest day. The Sprinter took one attempt every time. The F 150 was first attempt every time.
For comparison, the smaller GB40 started the Ram on the third attempt in similar conditions and did not have enough headroom to start the Sprinter at all once the diesel glow plug load was added.
USB C Power Delivery: the real upgrade
The USB C PD implementation is the meaningful generational improvement over the older GB series. Recharge from full empty took 87 minutes in our test using an Anker 65W laptop adapter, within margin of NOCO’s 90 minute claim. With a 30 watt phone PD adapter, recharge took roughly 3 hours. With an 18 watt phone charger, recharge took just over 4.5 hours.
Output side, the 60 watt PD socket charges most modern laptops at full rate. We charged a 14 inch MacBook Pro, a Dell XPS 13, and an iPad Pro 13 inch from the GBX55, all at full PD speed. As an emergency laptop power bank, this is a genuine secondary use case that older lead acid jump starters cannot match.
Charge retention and weather durability
Across a 14 month bench test, our GBX55 retained roughly 82 percent of starting capacity left untouched, similar to the GB40. NOCO recommends a 6 to 12 month full recharge cycle, and we agree.
The GBX55’s larger thermal mass made a real difference in summer parked cabin tests. Where a smaller jump starter degrades faster in 110 F cabin heat, the GBX55 maintained roughly 95 percent capacity over a Texas summer. Lithium chemistry hates heat regardless of brand, so a windshield sunshade and trunk storage (in moderate temperatures) extend the life of any of these tools.
For full jump starter test methodology, see our methodology page. If you have a smaller engine or a tighter budget, see our review of the NOCO Boost Plus GB40.
NOCO Boost X GBX55 Lithium Jump Starter vs. the competition
| Product | Our rating | Peak | Capacity | Recharge | Price | Verdict |
|---|---|---|---|---|---|---|
| NOCO Boost X GBX55 | ★★★★★ 4.6 | 1750A | 32Wh | 90 min | $159 | Top Pick Premium |
| NOCO Boost Plus GB40 | ★★★★★ 4.7 | 1000A | 24Wh | 180 min | $99 | Editor's Choice |
| AVAPOW 6000A | ★★★★☆ 4.3 | 6000A claimed | 26Wh | 180 min | $89 | Best Budget |
| Schumacher SL1639 | ★★★★☆ 4.0 | 1200A | 22Wh | 240 min | $139 | Recommended |
Full specifications
| Peak current | 1750 amps |
| Battery type | Lithium ion |
| Battery capacity | 32 watt hours |
| Engine compatibility | Gas up to 7.5L, diesel up to 4.0L |
| Number of starts | Up to 30 per charge |
| USB C | 60W Power Delivery, in and out |
| Output voltage | 12V |
| Flashlight | 100 lumen with 7 modes |
| Weight | 3.1 pounds |
| Recharge time | 90 minutes via USB C PD |
| Operating temperature | negative 20 C to 50 C |
| Warranty | 3 year manufacturer |
Should you buy the NOCO Boost X GBX55 Lithium Jump Starter?
The NOCO Boost X GBX55 is the right step up from the GB40 if you drive a V8 truck or a small diesel. 1750 peak amps cranks gas engines up to 7.5 liters and diesels up to 4.0 liters with no drama. USB C Power Delivery in and out is the headline upgrade over the older GB series. The 60 watt PD output also makes it a serious laptop power bank when not jumping cars.
Frequently asked questions
Is the GBX55 worth the extra $60 over the GB40?+
Yes if you own a V8 truck, a small diesel, or a vehicle that lives in cold weather. The 1750 amps starts engines the GB40 will struggle with, and USB C PD recharge cuts your top off time in half. For a sedan or commuter, the GB40 is the smarter buy.
Will the GBX55 start a 6.7L diesel?+
It is rated up to 4.0 liters of diesel. A 6.7L Cummins or Power Stroke needs the larger NOCO GBX155 (3000 amps) or a heavy duty corded unit. The GBX55 will start small diesels (2.0 to 4.0L) reliably.
How fast does the USB C Power Delivery recharge?+
Roughly 90 minutes from fully empty using a 60 watt USB C PD charger. Slower phone chargers will take 3 to 5 hours. Use a real laptop class PD adapter to hit the rated time.
Can I use the GBX55 to charge my laptop?+
Yes. The 60W USB C PD output charges most 13 to 15 inch laptops at full speed. We use ours regularly as a backup laptop battery on long site visits.
Does the GBX55 come with a USB C cable?+
No. NOCO ships a USB A to micro USB cable in the box, which is odd given the product is built around USB C. Plan to add a 60W rated USB C cable separately.
📅 Update log
- May 10, 2026Initial review published with cold weather diesel start tests.
Alex Patel
Alex Patel writes for The Tested Hub.
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