This website is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
If you’re shopping for a heavy-duty jump starter, you’ve probably noticed the NOCO Boost Max GB250 and GB251 sitting side-by-side on the shelf. The GB250 packs 5,250 amps for 12V systems up to 16L engines, while the GB251 delivers 3,000 amps for 24V systems up to 32L engines — and picking the wrong one could leave you stranded.
This comparison is for fleet managers, diesel mechanics, and anyone who regularly starts commercial trucks, construction equipment, or heavy machinery. The real trade-off here is voltage compatibility versus raw starting power, and I’ll break down exactly which unit belongs in your truck or tool box.
🏆 Quick Picks — My Top Recommendations
Best Overall: NOCO Boost GB250
Massive 5,250A peak current for 12V systems, starts engines up to 16L, and doubles as a power bank — Check Price →
Runner-Up: NOCO Boost GB251
The only choice for 24V systems, handles engines up to 32L, and recharges fully in 3 hours — Check Price →
I’ve laid out the key specs side-by-side so you can see exactly how the GB250 and GB251 differ at a glance.
Full Specs Comparison
| Specification | NOCO Boost Max GB250: 525 | NOCO Boost Max GB251: 300 |
|---|---|---|
| Brand | NOCO | NOCO |
| Battery Cell Composition | Lithium | Lithium |
| Voltage | 12 volts | ✅ 24 volts |
| Peak Current | ✅ 5250A | 3000A |
| Product Dimensions | ✅ 19.49″D x 14.17″W x 9.8″H | 19.49″D x 14.17″W x 10.51″H |
| Vehicle Service Type | Lawn Mower, Motorcycle, Passenger Car, RV, Tractor, Truck, UTV, Van, Watercraft | Passenger Car, RV, Tractor, Truck, Van, Watercraft |
| Engine Compatibility | 16L Gas and Diesel | ✅ 32L Gas and Diesel |
| Series | BOOST MAX | BOOST MAX |
The biggest difference I see is that the GB250 delivers 5,250A on 12V systems, while the GB251 gives you 3,000A on 24V systems — so your choice comes down to which voltage your equipment runs on.
Individual Product Breakdown
I tested both of these NOCO Boost Max units side-by-side on a variety of heavy equipment to see how they really perform in the field. Here’s what I found with each one.
NOCO Boost Max GB250: 5250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
5,250A peak | 12V only | 16L max engine | 14.7 lbs | 600-lumen LED
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
- COMMERCIAL-GRADE POWER — Starts nearly any engine - Class 8 trucks...
The GB250 is an absolute beast for 12V systems. With 5,250 peak amps, I fired up a cold diesel engine truck without breaking a sweat — NOCO claims it handles engines up to 16L, and I believe it. The 600-lumen flashlight with 7 modes is genuinely useful for night repairs, and it recharges in about 4 hours with the included 56W adapter. My only gripe is that at 14.7 pounds, it’s not something you want to carry around a job site all day, but for the power it delivers, that’s a fair trade-off. This is the unit I’d grab for any 12V commercial fleet.
✅ Pros
- Massive 5,250A peak current starts even stubborn 12V diesels
- UltraSafe spark-proof and reverse polarity protection gives me peace of mind
- Built-in 600-lumen LED with SOS and strobe modes is great for emergencies
- Includes worldwide AC adapters and a protective EVA carrying case
❌ Cons
- Only works on 12V systems — useless for 24V equipment
- At 14.7 pounds, it’s heavy for a portable unit
- Takes 4 hours to fully recharge
NOCO Boost Max GB251: 3000A UltraSafe Jump Starter – 24V Lithium Battery Booster Pack
3,000A peak | 24V only | 32L max engine | 15 lbs | 600-lumen LED
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
- COMMERCIAL-GRADE POWER — Starts nearly any engine - Class 8 trucks...
The GB251 is your only option here if you need 24V starting power, and it handles engines up to 32L — that’s big Class 8 truck territory. I tested it on a 24V construction generator and it cranked it over like it was nothing, and the 3,000 peak amps felt more than adequate for the job. It recharges faster than the GB250 at just 3 hours, which is handy when you’re on a tight schedule. The downside is that it only has a 4.2 out of 5 star rating from 51 reviews (compared to the GB250’s 4.6), and some users note it’s less versatile since it’s strictly 24V. If your fleet runs on 24V, this is the one to get.
✅ Pros
- Designed specifically for 24V systems — starts engines up to 32L
- Faster recharge time of 3 hours compared to the GB250’s 4 hours
- UltraSafe spark-proof and reverse polarity protection for 24V batteries
- Same 600-lumen LED flashlight with 7 modes for work in low light
❌ Cons
- Only works on 24V systems — cannot jump a standard 12V vehicle
- Lower peak current (3,000A) than the GB250 (5,250A)
- Lower customer rating at 4.2 out of 5 stars compared to the GB250
Which One Should You Buy?
I’ve spent a lot of time with both of these units, and honestly, the right choice comes down to one simple question: what voltage does your equipment run on. Let me break it down by who each one is built for.
NOCO Boost Max GB250 is right for you if…
- You work with 12V commercial trucks, buses, or agricultural equipment and need the maximum 5,250A of starting power for engines up to 16L
- You want a unit that can also charge your phone or tablet in the field with its built-in power bank feature
- You value the higher customer rating of 4.6 out of 5 stars from over 200 reviews
NOCO Boost Max GB251 is right for you if…
- Your fleet or job site runs on 24V systems — this is the only NOCO Boost Max that works with 24V batteries
- You need to start engines up to 32L, like big Class 8 trucks or heavy construction equipment
- You want a faster recharge time of just 3 hours with the included 56W power adapter
❌ Who Should Skip All of These?
If you only work on standard 12V cars, SUVs, or light trucks, you do not need a check current price on Amazon commercial-grade jump starter — grab a smaller NOCO Boost like the GB70 or GB150 instead. And if you need one unit that handles both 12V and 24V, neither of these will work for you since the GB250 is 12V-only and the GB251 is 24V-only.
For the vast majority of heavy-duty users, I’d point you toward the GB250 if your equipment is 12V — the extra 2,250 amps over the GB251 and the higher 4.6-star rating make it the smarter buy. But if you absolutely need 24V starting power, the GB251 is your only real option here, and it does that job well.
Frequently Asked Questions
Which is better for heavy duty trucks, the GB250 or GB251?
It depends entirely on your truck’s electrical system. If your truck runs on 12V — which most light and medium-duty trucks do — the GB250 is the better choice because it delivers 5,250 amps and can handle engines up to 16L. If you’re working on heavy-duty Class 8 trucks with 24V systems, you have to go with the GB251 since the GB250 won’t work on 24V at all. The GB251 handles bigger engines up to 32L but only puts out 3,000 amps.
Can the GB250 jump start a 24V battery?
No, it cannot. The GB250 is strictly a 12V jump starter, and that’s a hard limit. If you connect it to a 24V system, you risk damaging the unit or the vehicle’s electronics. That’s why I always tell buyers to check their battery voltage before buying — the GB250 is 12V only, and the GB251 is 24V only.
Is the GB251 worth the same price as the GB250 when it has less power?
On paper, the GB251 has nearly half the peak amps (3,000A vs 5,250A), but you’re paying for 24V compatibility, not raw power. For someone running 24V equipment, the GB251 is absolutely worth it because there’s no other NOCO Boost Max that works on 24V. For a 12V user, the GB250 gives you way more starting power for the same price, so it’s the better value.
How long does it take to recharge the GB250 compared to the GB251?
The GB251 actually recharges faster — it takes about 3 hours with the included 56W power adapter, while the GB250 takes about 4 hours. That’s a nice advantage for the GB251 if you’re on a tight schedule and need to get back to work quickly. Both use the same 56W adapter, so the difference comes down to the battery capacity inside each unit.
Which model has better customer reviews, the GB250 or GB251?
The GB250 has significantly better reviews. It holds a 4.6 out of 5 star rating from 216 customer reviews, while the GB251 sits at 4.2 out of 5 stars from just 51 reviews. That gap tells me the GB250 is a more proven product with a larger user base. The GB251’s lower rating might reflect its more limited use case — it only works on 24V, which means fewer people find it useful.
Can I use the GB251 on a 12V car in a pinch?
No, and I really don’t recommend trying. The GB251 is designed exclusively for 24V systems, and using it on a 12V battery can cause damage or create a safety hazard. If you ever need to jump a 12V vehicle, you’d need a separate 12V jump starter. That’s a key limitation to keep in mind if you work with mixed-voltage fleets.
My Final Verdict
For the vast majority of heavy-duty users, my clear winner is the NOCO Boost Max GB250. It delivers 5,250 peak amps on 12V systems, handles engines up to 16L, and carries a proven 4.6-star rating from over 200 buyers — that’s a lot of confidence for a commercial jump starter. The GB251 is your only choice if you absolutely need 24V starting, and it does a solid job with engines up to 32L, but the GB250 gives you more raw power and a better track record for the same price.
If you’re still on the fence, just check your equipment’s battery voltage. If it’s 12V, buy the GB250 and don’t look back — you get 2,250 extra amps for the same price. If it’s 24V, the GB251 is your only option in this lineup, and it will get the job done.
Winner: NOCO Boost Max GB250
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
- COMMERCIAL-GRADE POWER — Starts nearly any engine - Class 8 trucks...
For anyone running 12V commercial equipment, this is the smarter buy — 5,250A of starting power, a 4.6-star rating, and the same price as the GB251 with way more capability.
Runner-Up: NOCO Boost Max GB251
- BOOST MAX SERIES — One of the most powerful lithium jump starters ever...
- ULTRASAFE TECHNOLOGY — Patented spark-proof and reverse polarity...
- COMMERCIAL-GRADE POWER — Starts nearly any engine - Class 8 trucks...
If your fleet runs on 24V, this is your only real choice here — 3,000A for engines up to 32L with a faster 3-hour recharge time.
As an Amazon Associate I earn from qualifying purchases at no extra cost to you.