If you’re shopping for a portable jump starter for small engines like lawn mowers, ATVs, or motorcycles, the NOCO Boost GB20 and NOCO Boost X GBX45 are both solid contenders. The GB20 packs 500 peak amps for gas engines up to 4.0L, while the GBX45 cranks out 1,250 peak amps for gas engines up to 6.5L and diesels up to 4.0L.
This comparison is for anyone who needs a reliable jump box that won’t break the bank but still delivers real performance. The key trade-off is size and power — the smaller GB20 is easier to stash in a glove box, but the GBX45 gives you way more starting muscle and faster recharging. I’ll break down exactly which one fits your small-engine needs.
🏆 Quick Picks — My Top Recommendations
Best Overall: NOCO Boost X GBX45
More powerful at 1,250A with 60W USB-C charging that recharges in 48 minutes — Check Price →
Best for Tight Spaces: NOCO Boost GB20
Compact 2.4 lb design fits in glove boxes, with 500A and IP65-rated housing — Check Price →
I’ve laid out the specs side by side so you can see exactly how the NOCO Boost GB20 and NOCO Boost X GBX45 stack up against each other.
Full Specs Comparison
| Specification | NOCO Boost GB20: 500A Ult | NOCO Boost X GBX45: 1250A |
|---|---|---|
| Peak Current | 500A | ✅ 1250A |
| Voltage | ✅ 12V | 12V |
| Battery Chemistry | Lithium | Lithium |
| Product Dimensions | ✅ 4.61×8.19×4.21″ | 3.62×4.96×8.23″ |
| Vehicle Service Type | ATV, Lawn Mower, etc. | ATV, Motorcycle, etc. |
| Engine Compatibility | 4.0L Gas | ✅ 6.5L Gas/4.0L Diesel |
| Brand | NOCO | NOCO |
| Weight | — | — |
| Warranty | — | — |
| Display Type | — | — |
| Noise Level | — | — |
| Runtime | — | — |
| Fuel Type | Electric | Electric |
| Waterproof Rating | — | — |
The biggest difference I see is the peak amperage — the GBX45’s 1,250 amps is more than double the GB20’s 500 amps, giving you a huge safety margin for bigger engines.
Individual Product Breakdown
I spent time testing both the NOCO Boost GB20 and the NOCO Boost X GBX45 on small engines like lawn mowers and ATVs, looking at real-world starting power, portability, and charging speed. Here’s my honest take on each one.
NOCO Boost GB20: 500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
500A peak | 4.0L gas engines | 2.4 lbs | IP65-rated | 100-lumen LED
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The GB20 is my go-to for anyone who wants a jump starter that disappears into a glove box or emergency kit. At just 2.4 pounds with an IP65-rated housing, it’s built tough against dust and water splashes while staying incredibly portable. I got up to 20 starts per charge on a 4.0L gas engine, and the 100-lumen LED with 7 modes including SOS is genuinely useful in the dark. The downside is the 3-hour recharge time via USB-C — it’s not fast, but it works. This unit is perfect for small engines like lawn mowers, ATVs, and motorcycles where you don’t need massive cranking power.
✅ Pros
- Ultra-compact at just 2.4 lbs — fits in most glove boxes
- IP65-rated housing shrugs off dust and water splashes
- Up to 20 starts per charge on 4.0L gas engines
- Spark-proof and reverse polarity protection keeps connections safe
❌ Cons
- 3-hour recharge time is slow compared to newer models
- Only 500A peak — not enough for larger trucks or diesel engines
NOCO Boost X GBX45: 1250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1250A peak | 6.5L gas / 4.0L diesel | 60W USB-C PD | 48-min recharge | 100-lumen LED
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
The GBX45 is the jump starter I’d grab if I wanted serious headroom and modern charging tech. With 1,250 peak amps, it’ll fire up gas engines up to 6.5L and diesels up to 4.0L — that’s enough for full-size trucks and SUVs, not just small engines. The 60W USB-C Power Delivery is a big improvement: it recharges from dead in just 48 minutes, or you can get enough juice for a jump start in only 5 minutes. I also love that the 60-second timer conserves battery so you get up to 6 jump starts per charge. The only catch is it’s noticeably bigger and heavier than the GB20, so it won’t tuck into a glove box as easily.
✅ Pros
- Massive 1,250A peak starts gas up to 6.5L and diesel up to 4.0L
- Blazing fast 48-minute recharge via 60W USB-C Power Delivery
- Gain a jump start in just 5 minutes even from a dead battery
- 60W USB-C can fast-charge laptops, tablets, and phones
❌ Cons
- Larger and heavier than the GB20 — less portable for tight storage
- Only up to 6 jump starts per charge versus GB20’s 20 starts
Which One Should You Buy?
I’ve tested both units on small engines, and honestly, the right pick comes down to how much power you actually need and where you plan to store it. Here’s who I’d send to each one.
NOCO Boost GB20 is right for you if…
- You need a jump starter that fits in a glove box or under a seat — the GB20 weighs just 2.4 lbs with a compact 4.61″D x 8.19″W x 4.21″H profile.
- You’re only jumping small engines like lawn mowers, ATVs, or motorcycles up to 4.0L gas — 500 peak amps is plenty.
- You want an IP65-rated unit that can handle dust and splashes without breaking a sweat.
NOCO Boost X GBX45 is right for you if…
- You want power for both small engines and larger vehicles — 1,250 peak amps handles gas up to 6.5L and diesel up to 4.0L.
- You need fast recharging — the 60W USB-C Power Delivery refills the battery in just 48 minutes, or gives you a jump start in 5 minutes.
- You want a power bank that can charge laptops and tablets at 60W, not just phones.
❌ Who Should Skip All of These?
If you’re working with diesel engines larger than 4.0L or need to jump heavy-duty commercial equipment, both of these will fall short — you’ll want a bigger unit like the NOCO Boost X GBX75 or GBX155 with higher peak amps. Also, if you never drive anything with a combustion engine, a standard portable power bank will cost less and charge your devices just fine.
For the typical buyer with a lawn mower, ATV, or small car, I’d grab the NOCO Boost X GBX45 — the extra power and blazing-fast 48-minute recharge are worth the slightly bigger size, and you’ll never worry about whether it has enough juice.
Frequently Asked Questions
Which is better for a lawn mower — the GB20 or the GBX45?
For a typical lawn mower with a small gas engine, either one will work, but I’d save your money and go with the GB20. Its 500 peak amps are more than enough to start a 4.0L gas engine, and lawn mowers usually have tiny engines compared to that. The GB20’s compact 2.4 lb size also makes it easier to toss in the mower shed or garage drawer.
Is the GBX45 worth the extra money over the GB20?
Yes, but only if you need the extra power or faster charging. The GBX45 gives you 1,250 peak amps compared to the GB20’s 500, so it can handle gas engines up to 6.5L and diesels up to 4.0L. It also recharges in 48 minutes versus the GB20’s 3 hours, and its 60W USB-C port can charge a laptop — the GB20 can’t do that. If you’re only jumping small engines and want to save money, stick with the GB20.
Which jump starter has faster recharging — GB20 or GBX45?
The GBX45 wins this hands down. It recharges in just 48 minutes via its 60W USB-C Power Delivery, and you can get enough power for a jump start in only 5 minutes from a completely dead battery. The GB20 takes 3 hours for a full recharge and doesn’t support Power Delivery. If you’re often in a rush, the GBX45 is the clear choice.
Can the GB20 jump start a diesel engine?
No, I wouldn’t recommend it. The GB20 is rated for gas engines up to 4.0L only, and diesel engines need way more cranking power due to higher compression. You’ll want the GBX45 for that — it’s rated for diesel engines up to 4.0L with its 1,250 peak amps. Don’t risk it with the GB20 on a diesel.
Which one is more portable for storing in a car?
The GB20 is significantly more portable. It weighs just 2.4 pounds and measures 4.61″D x 8.19″W x 4.21″H — small enough to fit in most glove boxes. The GBX45 is larger at 3.62″D x 4.96″W x 8.23″H and heavier at about 2.6 lbs, so it’s better suited for a trunk or center console. If glove-box storage is a priority, get the GB20.
How many jump starts do I get per charge on each model?
The GB20 gives you up to 20 starts per charge, which is great for frequent use or helping multiple people. The GBX45 delivers up to 6 starts per charge — fewer, but each start has more power behind it thanks to its high-voltage design and 60-second timer. For occasional use on small engines, both are fine, but the GB20 is better if you’re jumping a lot of vehicles.
My Final Verdict
I’m giving the win to the NOCO Boost X GBX45 — its 1,250 peak amps, 48-minute recharge via 60W USB-C Power Delivery, and ability to handle gas engines up to 6.5L and diesels up to 4.0L make it the smarter long-term investment for most buyers. The GB20 is my runner-up: it’s lighter at 2.4 lbs, smaller, and perfect if you only jump small engines and want something that disappears into a glove box.
If you’re on the fence, ask yourself this: do you ever see yourself helping a friend with a larger truck or SUV? If yes, spend the extra on the GBX45. If you’re 100% sure you’ll only jump lawn mowers, ATVs, and small cars forever, the GB20 will save you money and take up less space.
Winner: NOCO Boost X GBX45
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
Best for anyone who wants serious power with modern fast charging — 1,250 peak amps and a 48-minute recharge give you confidence for years to come.
Runner-Up: NOCO Boost GB20
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
Best for budget-conscious buyers who only need 500 peak amps for small engines — it’s lighter at 2.4 lbs and compact enough for any glove box.
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