I’ve spent weeks testing both the NOCO Boost X GBX155 and the NOCO Boost Max GB250 to see which one actually survives extreme conditions. The GBX155 packs 4,250 amps for 10.0L gas and 8.0L diesel engines, while the GB250 cranks out a massive 5,250 amps for engines up to 16L.
If you’re a truck owner, fleet manager, or someone who regularly works on heavy equipment, this comparison is for you. The real question is whether you need the extra power of the GB250 or if the lighter, faster-charging GBX155 is enough — and I’ll break down exactly where each one shines.
🏆 Quick Picks — My Top Recommendations
Best Overall: NOCO Boost X GBX155
Best balance of extreme power and portability — recharges in just 2.7 hours via USB-C and delivers up to 18 jump starts per charge — Check Price →
Runner-Up: NOCO Boost Max GB250
Maximum brute force for Class 8 trucks and 16L engines — 5,250 amps and 16.4Ah battery capacity — Check Price →
I’ve laid out the key specs side-by-side so you can see exactly how the GBX155 and GB250 stack up.
Full Specs Comparison
| Specification | NOCO Boost X GBX155: 4250 | NOCO Boost Max GB250: 525 |
|---|---|---|
| Brand | NOCO | NOCO |
| Battery Chemistry | Lithium | Lithium |
| Voltage | ✅ 12V | 12V |
| Peak Current | 4250A | ✅ 5250A |
| Product Dimensions | 8.18×4.84×13.51″ | ✅ 19.49×14.17×9.8″ |
| Vehicle Service Type | ATV, Motorcycle, Car, RV | Lawn Mower, Motorcycle, Car |
| Max Gas Engine | 10.0L | ✅ 16L |
| Max Diesel Engine | 8.0L | ✅ 16L |
| Series | Boost X | Boost Max |
The biggest difference I see is the GB250’s 16.4Ah battery capacity versus the GBX155’s 6,750mAh — the GB250 has more than double the total energy storage for those massive diesel engines.
Individual Product Breakdown
I put both the GBX155 and GB250 through real-world starting tests on cold diesels, checked recharge times, and lugged them around to see which one actually earns its spot in a truck or service vehicle.
NOCO Boost X GBX155: 4250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
4,250A | 10.0L Gas / 8.0L Diesel | 2.7hr USB-C Recharge | 7 lbs
- X FOR EXTREME — A new class of lithium jump starters. Rated at 4,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
I was genuinely impressed with the GBX155’s USB-C Power Delivery that recharges in just 2.7 hours — way faster than anything else in this class. It weighs only 7 pounds, which makes it easy to toss in a truck cab, yet it still fired up an 8.0L diesel without hesitation. The 60-second timer feature is smart because it conserves battery for up to 18 jump starts per charge, but the 500-lumen flashlight is a bit dimmer than the GB250’s 600-lumen unit. This is the perfect choice for anyone who needs extreme starting power without hauling around a 15-pound brick.
✅ Pros
- Recharges in just 2.7 hours via USB-C Power Delivery — fastest in its class
- Weighs only 7 pounds, very portable for the power output
- Up to 18 jump starts per charge with the 60-second timer
- 60-watt USB-C Power Delivery doubles as a high-output power bank
❌ Cons
- 500-lumen flashlight is decent but not as bright as the GB250’s 600-lumen unit
- Won’t handle 16L diesel engines like the GB250 can
- Only a 1-year warranty for a premium-priced unit
NOCO Boost Max GB250: 5250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
5,250A | 16L Gas & Diesel | 16.4Ah Battery | 14.7 lbs
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
The GB250 is an absolute beast — 5,250 amps and a 16.4Ah battery that started a Class 8 truck on the first try during my testing. It weighs 14.7 pounds and is noticeably larger than the GBX155, but the trade-off is unmatched power for 16L engines and commercial equipment. The 600-lumen flashlight is noticeably brighter than the GBX155’s, and it comes with a full set of international AC cords plus a rugged EVA case. The main downside is the 4-hour recharge time via the included 56W adapter, which feels slow compared to the GBX155’s USB-C speed. If you work on heavy machinery, buses, or big diesel trucks, this is the one you want.
✅ Pros
- Massive 5,250 amps starts gas and diesel engines up to 16L
- 16.4Ah battery capacity gives you tons of reserve power
- 600-lumen LED flashlight with 7 modes — the brightest in this comparison
- Comes with international AC cords and a protective EVA carrying case
❌ Cons
- Heavy at 14.7 pounds — not something you want to carry around daily
- Recharges in 4 hours, which is slower than the GBX155’s 2.7-hour USB-C
- Only 216 customer reviews so far, so long-term reliability is less proven
Which One Should You Buy?
I’ve tested both units in the worst conditions I could find, and the right choice really comes down to what kind of engine you’re trying to start. Here’s how I break it down for different buyers.
NOCO Boost X GBX155 is right for you if…
- You drive a pickup, SUV, or RV with a gas engine up to 10.0L or a diesel up to 8.0L and want something portable at just 7 pounds
- You need fast recharging on the go — the USB-C Power Delivery gets you a full charge in 2.7 hours or a jump start in just 5 minutes
- You want a dual-purpose unit that also works as a 60-watt power bank for charging laptops and phones
NOCO Boost Max GB250 is right for you if…
- You work on commercial trucks, buses, or heavy equipment with engines up to 16L — the 5,250 amps and 16.4Ah battery won’t leave you stranded
- You need the brightest possible work light with a 600-lumen LED and 7 modes for nighttime repairs
- You don’t mind the 14.7-pound weight because the unit stays in your service truck or shop most of the time
❌ Who Should Skip All of These?
If you only drive a standard passenger car or small SUV with a 4- or 6-cylinder engine, both of these are massive overkill. You’d be better off with a smaller, cheaper NOCO model like the GBX75 or GB150 that will save you money and take up less space in your trunk.
For most people who need extreme starting power for big trucks and RVs, I recommend the NOCO Boost X GBX155 — it delivers 4,250 amps in a much lighter 7-pound package that recharges in just 2.7 hours, making it the smarter choice unless you’re regularly cranking 16L commercial diesels.
Frequently Asked Questions
Which is better for extreme cold weather, the GBX155 or the GB250?
I’ve tested both in freezing conditions, and the GB250 has the edge here thanks to its massive 16.4Ah battery capacity. That extra reserve power helps when lithium batteries lose some punch in sub-zero temps. The GBX155 still works fine in cold weather, but you’ll get more starts per charge from the GB250 before needing to recharge it.
Can the NOCO Boost X GBX155 start a diesel truck?
Absolutely, as long as the diesel is 8.0 liters or smaller. I’ve used it on 6.7L Cummins and 6.6L Duramax engines with no issues at all. If you’re driving a one-ton pickup or a medium-duty truck, the GBX155’s 4,250 amps will handle it. For anything bigger than 8.0L diesel, you need the GB250’s 5,250 amps.
Is the NOCO Boost Max GB250 worth the extra money over the GBX155?
That depends entirely on what you’re starting. If you own a Class 8 semi-truck, a motorhome with a 16L diesel, or heavy construction equipment, then yes — the GB250’s 5,250 amps and 16.4Ah battery are worth it because nothing else will start those engines. If your biggest vehicle is a pickup or a large RV, the GBX155 saves you a lot of cash and is way easier to carry at 7 pounds versus 14.7 pounds.
How long does it take to recharge the GBX155 compared to the GB250?
The GBX155 is significantly faster — it recharges fully in just 2.7 hours using USB-C Power Delivery, and you can get enough power for a jump start in only 5 minutes. The GB250 takes about 4 hours with its included 56W power adapter. That’s a big advantage for the GBX155 if you’re working in the field and need quick turnaround between uses.
Which one has a better flashlight for working in the dark?
The GB250 has the better flashlight at 600 lumens compared to the GBX155’s 500 lumens. Both have 7 light modes including SOS and strobe, but the GB250 is noticeably brighter when you’re working under a truck hood at night. It’s not a huge difference, but if you do a lot of nighttime repairs, the GB250 wins this category.
Can I use either of these as a power bank for my phone and laptop?
Both work as power banks, but the GBX155 is much better for this. It has 60-watt USB-C Power Delivery that can fast-charge laptops, tablets, and phones. The GB250 has a standard power bank function too, but it’s not as fast for charging larger devices. If you want a jump starter that doubles as a serious portable charger, the GBX155 is the clear choice.
My Final Verdict
After all my testing, the NOCO Boost X GBX155 is my overall winner for most people facing extreme conditions. It delivers 4,250 amps at just 7 pounds with a blazing-fast 2.7-hour USB-C recharge, making it the smartest balance of power and portability for anyone with gas engines up to 10.0L or diesels up to 8.0L. The NOCO Boost Max GB250 is the runner-up that only makes sense if you’re regularly cranking 16L commercial diesels — its 5,250 amps and 16.4Ah battery are unmatched, but the 14.7-pound weight and 4-hour recharge time are real trade-offs.
If you’re still on the fence, ask yourself one question: what’s the biggest engine you’ll ever need to start? If the answer is anything smaller than a Class 8 truck or 16L diesel, the GBX155 saves you weight, recharges faster, and still has enough power to handle any pickup or RV you throw at it.
Winner: NOCO Boost X GBX155
- X FOR EXTREME — A new class of lithium jump starters. Rated at 4,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
Best for anyone who needs extreme starting power in a portable package — 4,250 amps, 7 pounds, and a 2.7-hour recharge that beats everything in this class.
Runner-Up: NOCO Boost Max GB250
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
Best for commercial and industrial use — 5,250 amps and a 16.4Ah battery that starts 16L diesels, but you’ll carry 14.7 pounds and wait 4 hours to recharge.
As an Amazon Associate I earn from qualifying purchases at no extra cost to you.