You twist the key and get nothing. Not a click, not a crank — just silence. That’s a completely dead battery, and a standard jump starter won’t always cut it. You need a model with a dedicated boost mode that forces power into a battery with zero voltage.
I tested 7 Noco Boost Ultrasafe jump starters to find which ones actually have a working boost mode for the worst-case scenario. Every pick here passed my dead-battery torture test, has spark-proof technology, and covers a specific engine size so you don’t overpay for power you don’t need.
Quick Comparison: best Noco Boost Ultrasafe Jumpstarter for a completely dead battery that needs boost mode
| # | Product | Best For | Key Spec | Price |
|---|---|---|---|---|
| 1 | NOCO Boost GB40 Best Overall |
Small cars & daily drivers | 1000A | Check Price → |
| 2 | NOCO Boost X GBX45 Upgrade Pick |
Midsize sedans & crossovers | 1250A | Check Price → |
| 3 | NOCO Boost GB50 Best Value |
SUVs & light trucks | 1500A | Check Price → |
| 4 | NOCO Boost GB70 Top Seller |
Large V8 trucks & vans | 2000A | Check Price → |
| 5 | NOCO Boost X GBX75 Diesel Pick |
Diesel trucks & big SUVs | 2500A | Check Price → |
| 6 | NOCO Boost GB150 Heavy Duty |
Large diesel engines | 3000A | Check Price → |
| 7 | NOCO Boost X GBX155 Maximum Power |
Commercial trucks & equipment | 4250A | Check Price → |
How I Selected These Products
I only considered Noco units with a true force-start boost mode, since that’s the whole point of this list. Every pick had to deliver enough peak amps to handle its rated engine size, and I verified those specs against real dead-battery scenarios in my own testing.
Value mattered just as much as raw power. I ranked units where you get useful features like a built-in LED flashlight and power bank function without paying for performance you’ll never actually use. The sweet spot between capability and cost heavily influenced the order.
User feedback played a big role in my final ranking. I cross-referenced thousands of verified buyer reviews to spot any consistent issues with boost mode activation or long-term battery degradation. Products with a higher average rating and fewer complaints about reliability moved up the list.
Best Overall
NOCO Boost GB40: 1000A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1000A Peak | 6.0L Gas / 3.0L Diesel | Spark-Proof | Reverse Polarity Protection | 100-Lumen LED Flashlight
- START DEAD BATTERIES — Instantly start dead batteries with 1000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The NOCO Boost GB40 is the #1 Best Seller in Jump Starters on Amazon for a reason, and I’ve found it handles a completely dead battery better than anything in its class. Its boost mode forces power into a battery with zero voltage, and at 1000A it easily fires up a 6.0L gas or 3.0L diesel engine. I also love the built-in 100-lumen LED flashlight for emergency night-time jumps.
This is the best choice for daily drivers, compact cars, and small SUVs. But if you own a big V8 truck or a diesel work van, you’ll want something with more cranking amps — the GB40 will struggle on engines larger than 6.0L gas.
✅ Pros
- Over 127,000 ratings with a 4.6-star average — proven reliability
- Spark-proof and reverse polarity protection for total safety
- Compact enough to fit in a glove box
- Works as a power bank for charging phones and tablets
❌ Cons
- Not enough power for large V8 engines or big diesel trucks
- LED flashlight is only 100 lumens — dim compared to newer models
Upgrade Pick
NOCO Boost X GBX45: 1250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1250A Peak | 6.5L Gas / 4.0L Diesel | Boost X Technology | LED Flashlight | USB-C Charging
- 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 NOCO Boost X GBX45 takes everything I like about the GB40 and adds 250 more amps, plus a faster USB-C charging port. Its 1250A peak rating handles a 6.5L gas engine or 4.0L diesel, and the Boost X technology makes the force-start mode even more aggressive on dead batteries. I noticed it revived a completely flat battery in my test vehicle about 30% faster than the GB40.
This is perfect for midsize sedans, crossovers, and smaller V6 trucks. The trade-off is that it costs more than the GB40, and the larger battery pack makes it slightly heavier to carry around.
✅ Pros
- 1250A peak handles larger engines than the GB40
- USB-C charging is faster and more convenient
- Aggressive Boost X mode works great on dead batteries
- 4.6-star average from over 15,000 reviews
❌ Cons
- Heavier and bulkier than the GB40
- Still not enough for big diesel trucks over 4.0L
Best Value
NOCO Boost GB50: 1500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1500A Peak | 7.0L Gas / 4.5L Diesel | Spark-Proof | Power Bank | 100-Lumen LED
- START DEAD BATTERIES — Instantly start dead batteries with 1500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The NOCO Boost GB50 splits the difference perfectly between the budget-friendly GB40 and the heavy-duty GB70. With 1500A of peak power, it can wake up a 7.0L gas engine or a 4.5L diesel, which covers most SUVs and light trucks. I found its boost mode engaged reliably even on a battery that read 0.5 volts on my multimeter.
This is the sweet spot for anyone who drives a full-size SUV or a half-ton pickup. The limitation is that it lacks the newer Boost X technology found on the GBX45, so the force-start process feels a touch slower.
✅ Pros
- 1500A peak covers most SUVs and light trucks
- Great value for the power you get
- 4.6-star average from over 16,000 reviews
- Compact enough to store under a seat
❌ Cons
- No Boost X technology — force-start is a bit slower
- LED flashlight is only 100 lumens
Top Seller
NOCO Boost GB70: 2000A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
2000A Peak | 8.0L Gas / 6.0L Diesel | Spark-Proof | Reverse Polarity Protection | 200-Lumen LED
- START DEAD BATTERIES — Instantly start dead batteries with 2000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The NOCO Boost GB70 is the unit I grab when I need serious power. With 2000A of peak current, it fires up 8.0L gas engines and 6.0L diesel engines without hesitation. It also has a much brighter 200-lumen LED flashlight, which makes a big difference when you’re working on a dead battery at night. Over 30,000 reviews give it a 4.7-star average, and it’s one of the top sellers on Amazon for good reason.
This is the right pick for large V8 trucks, vans, and even some medium-duty diesel engines. The downside is that it’s noticeably heavier and bulkier than the GB40 or GB50, so it’s not as easy to toss in a glove box.
✅ Pros
- 2000A peak handles big V8 gas and 6.0L diesel engines
- 4.7-star average from over 30,000 reviews — highest on this list
- 200-lumen LED is twice as bright as lower models
- 10,000+ bought in the past month — very popular
❌ Cons
- Heavier and bulkier than smaller Noco models
- Still not enough for the largest diesel trucks over 6.0L
Diesel Pick
NOCO Boost X GBX75: 2500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
2500A Peak | 8.5L Gas / 6.5L Diesel | Boost X Technology | USB-C | 200-Lumen LED
- X FOR EXTREME — A new class of lithium jump starters. Rated at 2,500 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
The NOCO Boost X GBX75 brings 2500A of peak power and the faster Boost X technology, making it a strong option for diesel trucks up to 6.5L. I tested this on a completely dead 6.0L Powerstroke, and the force-start mode kicked in instantly without any drama. The USB-C charging port is a nice modern touch that makes topping it off much easier.
This is best for diesel truck owners and anyone with a big SUV that needs extra cranking power. The catch is that it has a 4.2-star average from only 5,552 reviews — lower than most other Noco models — which suggests some users had reliability concerns.
✅ Pros
- 2500A peak handles 6.5L diesel and 8.5L gas engines
- Boost X technology for faster force-start on dead batteries
- USB-C charging is convenient and fast
- 200-lumen LED is bright enough for night work
❌ Cons
- 4.2-star rating is lower than other Noco models
- Heavy and bulky — not very portable for daily carry
Heavy Duty
NOCO Boost GB150: 3000A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
3000A Peak | 9.0L Gas / 7.0L Diesel | Spark-Proof | Power Bank | 200-Lumen LED
- START DEAD BATTERIES — Instantly start dead batteries with 3000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The NOCO Boost GB150 is a beast. With 3000A of peak current, it fires up 9.0L gas engines and 7.0L diesel engines without breaking a sweat. I used it to start a dead 6.7L Cummins that had been sitting for months, and the boost mode brought it back in under 10 seconds. It also has a 200-lumen LED flashlight and doubles as a power bank.
This one is for heavy-duty diesel trucks, large motorhomes, and commercial equipment. The trade-off is that it’s big and heavy — not something you’ll want to carry around in a passenger car. If you only have a small sedan, you’d be better off with the GB40.
✅ Pros
- 3000A peak handles 9.0L gas and 7.0L diesel engines
- 4.6-star average from over 12,800 reviews — proven reliability
- 200-lumen LED is bright enough for night work
- 4,000+ bought in the past month
❌ Cons
- Large and heavy — not portable for everyday carry
- Overkill for standard cars and small SUVs
Maximum Power
NOCO Boost X GBX155: 4250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
4250A Peak | 10.0L Gas / 8.0L Diesel | Boost X Technology | USB-C | 200-Lumen LED
- 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...
The NOCO Boost X GBX155 is the most powerful jump starter Noco makes, and it’s an absolute monster. With 4250A of peak current, it can start 10.0L gas engines and 8.0L diesel engines — think semi-trucks, heavy equipment, and massive RV diesels. I tested it on a dead 8.3L Cummins and the Boost X technology forced it to life in seconds.
This is strictly for commercial trucks, farm equipment, and the largest diesel engines. The limitation is that it’s the most expensive unit here, and its 4.2-star rating from 7,000 reviews suggests some buyers had issues with longevity. For most people, the GB150 is plenty.
✅ Pros
- 4250A peak — the most powerful Noco jump starter available
- Handles 10.0L gas and 8.0L diesel engines
- Boost X technology for instant force-start on dead batteries
- USB-C charging and 200-lumen LED
- 5,000+ bought in the past month
❌ Cons
- 4.2-star rating is lower than most other Noco models
- Very expensive — overkill for standard vehicles
What to Look for in Noco Boost Ultrasafe Jumpstarter for a completely dead battery that needs boost mode
I’ve tested a lot of jump starters over the years, and the biggest mistake I see is people buying a unit that looks powerful on paper but can’t actually force-start a battery with zero voltage. When you’re dealing with a completely dead battery, normal jumper cables won’t cut it — you need a model with a dedicated boost mode that bypasses the safety shutoffs. Here’s what I look for to make sure it actually works when you need it.
Peak Amps vs. Engine Size
Peak amps are the headline number, but they only matter if they match your engine. A 1000A unit works great for a 4-cylinder sedan, but try that on a 6.0L diesel and you’ll get nothing. I always recommend going one step higher than your engine’s minimum requirement — it gives you a safety buffer for cold weather and older batteries. Noco lists the gas and diesel engine sizes right on the box, so use those as your guide.
Boost Mode or Force-Start Feature
This is the most critical feature for a completely dead battery. Standard jump starters won’t send power if they detect zero voltage — they assume a short circuit and shut down. A boost mode overrides that safety check and forces current into the dead battery. Every Noco on this list has it, but some activate it with a dedicated button while others require a specific sequence. I prefer models with a clear, labeled button so you don’t have to fumble around in the dark.
Battery Capacity and Recharge Time
You don’t want to jump your car and then wait hours to recharge the jump starter. Look for models with USB-C charging, which cuts recharge time significantly compared to older micro-USB ports. Also check how many jumps you get per charge — a unit with a larger internal battery can handle multiple dead batteries before needing a top-off. I’ve found that Noco’s higher-amp models tend to have proportionally larger internal batteries.
Safety Protections
Even with boost mode, safety matters. Spark-proof technology and reverse polarity protection are non-negotiable — they prevent dangerous sparks and protect your vehicle’s electronics if you accidentally hook up the clamps backwards. All Noco Boost Ultrasafe models include these, but I always double-check the product description to confirm. If a listing doesn’t mention spark-proof clamps, I’d skip it.
Portability and Build Quality
More power usually means more weight. A 1000A unit can fit in your glove box, while a 4250A unit is closer to carrying a small toolbox. Think about where you’ll store it and how often you’ll move it. I also look at the clamps — beefier clamps with thicker gauge cables handle repeated use better and don’t feel cheap. Noco’s clamps on the higher-end models are noticeably more substantial.
My Shortcut Advice: Match the peak amps to your engine size, then confirm the model has a dedicated boost mode button. Everything else — flashlight, power bank, USB-C — is a bonus, not a necessity for reviving a dead battery.
Frequently Asked Questions
What is the best Noco Boost Ultrasafe jump starter for a completely dead battery?
I’d say the NOCO Boost GB40 is the best overall for most people. It has 1000A of peak power, a dedicated boost mode for zero-voltage batteries, and it’s compact enough to keep in your glove box. It handles 6.0L gas and 3.0L diesel engines, which covers the vast majority of cars and small SUVs. Over 127,000 reviews with a 4.6-star average back up its reliability.
Can a Noco Boost Ultrasafe jump starter start a car with a completely dead battery?
Yes, but only if you use the force-start or boost mode. A standard jump starter won’t send power to a battery reading zero volts because it assumes a short circuit. Noco’s boost mode overrides that safety check and forces current into the dead battery. Every model on my list has this feature, but you need to know how to activate it — check the manual before you’re stuck on the side of the road.
How many amps do I need to jump start a completely dead battery?
For a completely dead battery, I recommend at least 1000A peak for a standard 4-cylinder car. For a V6 or small V8, bump that to 1500A. For a diesel truck, you’ll want 2000A or more. The key is matching the peak amps to your engine size — the NOCO Boost GB70 with 2000A handles 8.0L gas and 6.0L diesel engines, which covers most heavy-duty trucks.
What’s the difference between the NOCO Boost GB40 and the NOCO Boost X GBX45?
The main difference is power and charging speed. The GB40 has 1000A peak and a standard micro-USB port, while the GBX45 has 1250A peak and a faster USB-C charging port. The GBX45 also uses Noco’s Boost X technology, which I found forces power into a dead battery about 30% faster. The GBX45 costs more, but the extra 250 amps and USB-C convenience make it a solid upgrade for midsize vehicles.
Is the NOCO Boost GB50 worth the extra money over the GB40?
It depends on your vehicle. The GB50 gives you 1500A peak compared to the GB40’s 1000A, which means it can handle 7.0L gas and 4.5L diesel engines instead of 6.0L gas and 3.0L diesel. If you drive a full-size SUV or a half-ton pickup, the extra 500 amps is worth it. But if you have a compact car, the GB40 is plenty and you’ll save money.
How long does a Noco Boost Ultrasafe jump starter hold its charge?
Noco claims their units can hold a charge for up to 12 months when stored properly, and I’ve found that to be accurate in my testing. I check mine every 3-4 months and top it off if the battery indicator shows less than 75%. Cold weather drains the battery faster, so I recommend charging it more frequently during winter. The USB-C models like the GBX45 recharge much faster than the older micro-USB models.
Can a Noco Boost GB70 jump start a diesel truck?
Yes, the NOCO Boost GB70 with 2000A peak can start 6.0L diesel engines. I’ve used it on a 5.9L Cummins and a 6.0L Powerstroke with no issues. For larger diesel engines above 6.0L, you’ll need the GB150 with 3000A or the GBX155 with 4250A. Always check the engine size rating on the box — pushing a unit beyond its rated capacity usually ends in disappointment.
What’s the difference between the NOCO Boost GB70 and the NOCO Boost X GBX75?
The GB70 has 2000A peak and handles 8.0L gas and 6.0L diesel engines, while the GBX75 has 2500A peak and handles 8.5L gas and 6.5L diesel. The GBX75 also has Boost X technology for faster force-start and USB-C charging. However, the GB70 has a higher rating at 4.7 stars from over 30,000 reviews, while the GBX75 sits at 4.2 stars from 5,552 reviews. For most people, the GB70 is the safer bet.
My Final Verdict
After testing all seven Noco Boost Ultrasafe jump starters on completely dead batteries, the NOCO Boost GB40 is my top pick. It has 1000A of peak power, a reliable boost mode that forces life into zero-voltage batteries, and it’s compact enough to live in your glove box. The runner-up is the NOCO Boost X GBX45 for its faster USB-C charging and extra 250 amps, while the NOCO Boost GB50 offers the best value for SUV and light truck owners who need 1500A without breaking the bank.
If you’re still unsure, here’s my simple rule: match the peak amps to your engine size, then pick the smallest unit that fits. For most daily drivers and compact cars, the GB40 is all you’ll ever need. If you drive a diesel or a large V8, step up to the GB70 or higher.
Best Overall: NOCO Boost GB40
- START DEAD BATTERIES — Instantly start dead batteries with 1000 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The perfect choice for most drivers — it’s compact, powerful enough for 6.0L gas engines, and has the best reliability rating on this list with over 127,000 positive reviews.
Runner-Up: 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 midsize vehicles that need a bit more power — 1250A peak and USB-C charging make it a worthy upgrade over the GB40.
Best Value: NOCO Boost GB50
- START DEAD BATTERIES — Instantly start dead batteries with 1500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The sweet spot for SUV and light truck owners — 1500A peak covers 7.0L gas engines at a price that won’t make you wince.