NOCO GB20 vs GB40: Which Jump Starter Should You Actually Buy?

The NOCO GB40 is the better choice for most drivers. It delivers 1000A of peak power, handles gas engines up to 6.0L and diesel up to 3.0L, and includes a built-in voltmeter the GB20 doesn’t have. The GB20 is a solid pick if you drive a compact car or motorcycle and want to save $20. Buy the GB40 if you drive a truck, SUV, or diesel vehicle. Buy the GB20 only for small gas engines up to 4.0L.

You’re looking at two NOCO jump starters that look almost identical in photos. Same shape. Same logo. Both fit in your glove compartment. So why does the price jump $20 between them?

I’m Alex Rahman, and I’ve tested portable jump starters on everything from Honda Civics to Ford F-250s. I’ll give you a straight answer here — no fluff, no filler.

The GB20 and GB40 are not the same product. One is built for small cars. The other handles trucks, diesels, and cold winters. Pick the wrong one and you’ll be stuck on the side of the road wishing you’d read this first.

Let’s get into it — the verdict is already waiting at the bottom if you want to skip ahead.

Product Overview: NOCO Boost GB20

The GB20 is NOCO’s entry-level lithium jump starter. It puts out 500 peak amps — enough for gas engines up to 4.0 liters. Think Honda Civics, Toyota Corollas, small SUVs, motorcycles, and ATVs.

It weighs under a pound in older versions, and the newer model checks in around 2.4 lbs with updated clamps. It’s IP65-rated — sealed against water and dust. You can use it in the rain without worry.

The GB20 doubles as a USB power bank. You can charge your phone while waiting for the engine to turn over. It also includes a built-in LED flashlight with 7 modes, including SOS and emergency strobe — useful for roadside situations at night.

Here’s the honest truth: the GB20 is great for what it’s designed for. But a lot of buyers choose it thinking “1000A is 1000A” — and that’s not how it works. The GB20 is rated at 500A, and it’s built for small engines. Put it on a truck with a 5.5L V8 in January, and it’ll likely refuse to work.

Product Overview: NOCO Boost GB40

The GB40 is NOCO’s mid-range workhorse. It delivers 1000 peak amps — twice the output of the GB20. It handles gas engines up to 6.0L and diesel engines up to 3.0L. That covers most trucks, SUVs, vans, and crossovers on the road today.

The GB40 also carries a larger internal battery (15Wh vs the GB20’s 6.5Wh). More energy stored means more jump starts before you need to recharge. It also holds its charge longer in storage — important if it’s sitting in your trunk for months between uses.

Here’s the feature most reviews miss: the GB40 has a built-in voltmeter. That means you can press one button and see your car battery’s voltage before you even try to jump start. If it reads 12.6V, your battery is healthy and probably just needed a boost. If it reads 11V, you’ve got a dying battery that needs replacing. That’s a genuinely useful diagnostic tool — and the GB20 simply doesn’t have it.

Multiple Amazon users also point out the 100-lumen LED flashlight with SOS and strobe modes is powerful enough to actually signal for help at night. That’s not a gimmick — it’s a real safety feature in an emergency.

Full Spec Comparison: NOCO GB20 vs GB40

Spec	NOCO GB20	NOCO GB40	Winner
Peak Current	500A	1000A	GB40
Engine Capacity (Gas)	Up to 4.0L	Up to 6.0L	GB40
Engine Capacity (Diesel)	Not rated	Up to 3.0L	GB40
Battery Capacity (Wh)	6.5Wh	15Wh	GB40
Jump Starts Per Charge	Up to 20	Up to 20	Tie
LED Lumens	100 lumens, 7 modes	100 lumens, 7 modes	Tie
Built-in Voltmeter	No	Yes	GB40
IP Rating	IP65	IP65	Tie
Weight	~2.4 lbs	~2.4 lbs	Tie
Manual Override	Yes	Yes	Tie
UltraSafe Technology	Yes	Yes	Tie
Charging Time (Standard)	~3 hours	~3 hours	Tie
Warranty	1 year (3 yr w/ registration)	1 year (3 yr w/ registration)	Tie
Price (Amazon)	~$79.95	~$99.95	GB20

Performance & Raw Power: Does the Extra Power Actually Matter?

The GB40 wins this category clearly. It delivers 1000A of peak power — exactly double what the GB20 offers at 500A. That gap matters more than most buyers realize.

Why Both Look Similar But Aren’t Equal

Both devices jump start vehicles. But peak amps tell only part of the story. The bigger question is: what happens when your battery is deeply discharged, it’s cold outside, or your engine is large?

Cold weather thickens engine oil. That increases the resistance the starter motor has to overcome. On a cold morning in December, a 4.0L engine might need significantly more cranking power than in July. The GB20’s 500A can struggle here. The GB40’s 1000A has the reserve to push through.

Cold Weather Performance — Where the GB40 Pulls Ahead

Lithium batteries lose efficiency in cold weather. At 0°F (-18°C), a lithium jump starter can lose 20–30% of its effective output. That means the GB20’s real-world cold cranking power drops noticeably. The GB40 starts with more reserve, so even with that cold-weather drop, it still has enough to get you going.

The GB20 is fine in temperate climates. But if you live somewhere that sees hard winters, the GB40 is the safer choice by a clear margin.

Portability & Design: Is Smaller Always Better?

On portability, both the GB20 and GB40 are surprisingly close — but the GB20 has a slight edge for ultra-compact storage needs.

Size and Weight in Real Use

The current versions of both units come in at about 2.4 lbs. That’s similar enough that portability isn’t a dealbreaker for either. Both fit in a glove compartment, bag, or backpack pocket easily.

If you’re a motorcyclist or want something genuinely tiny to carry in a jacket pocket, look at the older GB20 model (0.9 lbs) or consider the even more compact NOCO GBX45. For most car owners, though, the weight difference between the GB20 and GB40 won’t matter in daily use.

LED Flashlight — Basic Torch vs Emergency Safety Tool

Here’s where the specs start to converge — but not entirely. Both units now include a 100-lumen LED with 7 modes: high, medium, low, SOS, blink, strobe, and off.

100 lumens is genuinely useful at night. The SOS strobe is the kind of feature you hope you never need but are very glad to have when you do. This is a tie on paper, but the GB40’s larger battery means the LED will run longer before the unit needs recharging.

Price and Value: Is the NOCO GB40 Worth the Extra $20?

The GB40 costs about $20 more than the GB20. At first glance, that doesn’t sound like much. But the question is whether those $20 buy you something real — or just a bigger number on the box.

What You Actually Get for $20 More

For $20 more, the GB40 delivers: double the peak amps (1000A vs 500A), a larger internal battery (15Wh vs 6.5Wh), diesel engine compatibility (up to 3.0L), and — most importantly — a built-in voltmeter. That voltmeter alone has real monetary value. It tells you whether your battery needs a jump or needs replacing. That information can save you from buying a new battery when you just needed a jump — or from getting stranded again because you didn’t know your battery was dying.

When the GB20 Is the Smarter Buy

The GB20 makes sense if you drive a compact car with an engine under 4.0L gas, never drive in cold winters, and just want a reliable backup in your glove compartment. If that’s you, the GB20 does its job well and costs $20 less.

But for the majority of drivers — especially anyone with a truck, SUV, van, or diesel — the GB40 is worth every dollar of the upgrade.

Safety Features & Unique Tools: The Feature Most Reviews Miss

The GB40 wins this category — and it’s not close. It has a safety and diagnostic feature the GB20 simply doesn’t offer.

UltraSafe Technology and Reverse Polarity Protection (Both)

Both the GB20 and GB40 use NOCO’s UltraSafe Technology. Connect the clamps in the wrong order — red to negative, black to positive — and the unit detects it and refuses to activate. You’ll see a red LED instead of the white boost LED. Just swap the clamps and you’re good to go.

This spark-proof design is a genuine safety upgrade over traditional jumper cables. According to Clore Automotive’s lithium jump starter safety guide, one of the most critical factors in jump starter safety is the quality of the protection circuitry — and NOCO’s UltraSafe system is among the best in its price range. The Consumer Reports jump starter buying guide also emphasizes that heat storage is one of the most overlooked risks — a point worth keeping in mind for both models.

Built-in Voltmeter on the GB40 — Why It Matters More Than You Think

This is the feature almost no VS article mentions. The GB40 includes a built-in voltmeter that shows your vehicle battery’s voltage on its LED display. Press and hold the power button before connecting to your car, and you’ll get an instant reading.

A healthy 12V battery reads between 12.4V and 12.7V at rest. Below 12.0V, it’s struggling. Below 11.5V, it may be near the end of its life. Knowing that before you jump start your car is hugely valuable. It tells you whether one jump will get you to work, or whether you need to budget for a new battery this weekend.

Manual Override — What It Does and Why You Should Use It Carefully

Both the GB20 and GB40 include a Manual Override feature. Here’s what it does: the UltraSafe system needs to detect at least 2 volts from your battery to activate safely. If the battery is so deeply discharged that it reads below 2V, the unit won’t automatically engage.

Manual Override bypasses that check. You hold the power button for 3 seconds, the unit forces itself on, and you can attempt a jump start on a nearly dead battery. According to NOCO’s official Manual Override guide, this mode disables both the spark-proof protection and the reverse polarity detection. That means a mistake in Manual Override can cause sparks — or damage your battery, your vehicle’s electronics, or the jump starter itself.

Cable Length — The One Real-World Complaint You Should Know About

Here’s what most reviews skip entirely: the clamp cables on both the GB20 and GB40 are short. Multiple Amazon buyers with trucks and SUVs report that the cables barely reach the battery terminals when the engine is positioned deep in the bay. On motorcycles and compact cars, it’s fine. On a Ford F-250 with a large engine bay, you may find yourself fighting with the clamps just to make a solid connection.

NOCO sells extension cables (the GBC007 X-Connect adapter at ~$24.95) that add 18.5 inches of reach. If you own a large truck or van, budget for that accessory alongside the GB40.

Real-World Use Cases: Which NOCO Jump Starter Wins for Your Situation?

• Compact car (Honda Civic, Toyota Corolla, Hyundai Elantra): GB20 wins. The 500A is more than enough for a 1.5–2.0L gas engine. Save the $20.
• Truck or full-size SUV (Ford F-150, Chevy Silverado, Toyota Tundra): GB40 wins. These engines range from 3.5L to 6.2L — the GB20 won’t cut it reliably.
• Cold winter start (temperatures below 20°F / -7°C): GB40 wins. Its larger battery holds more effective cranking power when temperatures drop and lithium cells slow down.
• Diesel van or fleet vehicle (up to 3.0L diesel): GB40 wins. The GB20 is not rated for diesel engines. Don’t risk it.
• Motorcycle or ATV: GB20 wins. It’s the right size and power level for small engines. The GB40 is overkill and costs more.
• Fleet mechanic or mobile service tech: GB40 wins. The voltmeter lets you diagnose the vehicle battery before and after the jump. That’s a time-saver across multiple service calls in a day.

Who Should Buy the NOCO GB20?

• You drive a compact car, sedan, or small crossover with a gas engine under 4.0L
• You own a motorcycle, ATV, or small boat and want a lightweight backup starter
• You live in a mild climate and rarely deal with hard winters
• Budget matters and you want the most reliable option under $80
• You want something small enough to carry in a backpack or keep in a purse

Who Should Buy the NOCO GB40?

• You drive a truck, SUV, van, or any vehicle with a gas engine between 4.0L and 6.0L
• You own a diesel vehicle with an engine up to 3.0L
• You live somewhere with cold winters where cold starts are a regular challenge
• You want to check your battery’s voltage before and after a jump (the voltmeter pays for itself)
• You’re a fleet mechanic, roadside tech, or someone who jumps multiple vehicles regularly

Who Should NOT Buy Either One?

• If you drive a large diesel truck (6L+ diesel, like a Ford Power Stroke or Cummins), neither model is enough — look at the NOCO GB70 (2000A, ~$199.95) or GB150 (3000A) instead.
• If you need to jump start vehicles with dual batteries or 24V systems, you’ll need a commercial-grade unit — the GB40 won’t work for that application.
• If you’re on a very tight budget and have a small car, the HULKMAN Alpha 85 (~$59.99) is a capable alternative worth considering.

How to Maintain Your NOCO Jump Starter (Battery Care & Storage Tips)

Monthly Charging Habit

Both the GB20 and GB40 will self-discharge over time. NOCO recommends charging the unit at least once every 3 months — but once a month is better if you want maximum readiness. It takes about 3 hours from a standard USB outlet. Don’t wait until the charge indicator is blinking red before you remember.

Heat and Cold Storage Warning

Never store your jump starter in a hot car. Temperatures inside a parked vehicle in direct sunlight can exceed 140°F (60°C) on a summer day. That kind of heat degrades lithium batteries fast — often permanently. Store the unit indoors when not in active use, especially during summer. The same principle applies to extreme cold: don’t leave it in the trunk at -20°F for weeks. Warm it up indoors for 30 minutes before using it in very cold conditions.

Deep Discharge Warning

Letting a lithium battery drain completely to zero — and leaving it there for weeks or months — is one of the fastest ways to kill it permanently. If the GB20 or GB40 shows a low charge indicator, recharge it within a few days. Don’t set it in a drawer and forget it for six months.

Manual Override Abuse Warning

Manual Override is an emergency-only tool. Using it repeatedly — or using it as your default mode every time you jump start — stresses the internal battery and bypasses the safety systems that protect your vehicle’s electronics. If your car needs Manual Override to start regularly, the car battery is failing. Replace it. Don’t keep abusing your jump starter to compensate.

Final Verdict: NOCO GB20 vs GB40 — Which One Wins?

The GB40 is the better jump starter for most drivers. It delivers twice the peak amps, handles diesel engines, includes a voltmeter, and holds more charge for longer — all for $20 more.

Buy the GB20 if you drive a compact car or motorcycle and don’t need diesel capability or diagnostic tools. Buy the GB40 if you drive anything larger, live somewhere cold, or want the voltmeter to tell you when your battery is dying before it leaves you stranded.

My recommendation as Alex Rahman: spend the extra $20 and get the GB40. You’ll use the voltmeter more than you expect, and you’ll thank yourself the first time a cold winter morning rolls around.

Frequently Asked Questions

Which is better — the NOCO GB20 or GB40?

The GB40 is better for most drivers. It delivers 1000A of peak power versus the GB20’s 500A, supports diesel engines up to 3.0L, and includes a built-in voltmeter. The GB20 is only the better choice for compact cars and motorcycles with gas engines under 4.0L.

What is the difference between the NOCO GB20 and GB40?

The key differences are peak amps (500A vs 1000A), engine compatibility (4.0L gas only vs 6.0L gas and 3.0L diesel), battery capacity (6.5Wh vs 15Wh), and the GB40’s exclusive built-in voltmeter. The GB40 costs about $20 more but offers meaningfully more capability.

Is the NOCO GB40 worth the extra money?

Yes, for most drivers. The GB40’s built-in voltmeter alone is worth the price difference — it tells you whether your battery needs a jump or needs replacing. If you drive a truck, SUV, or diesel vehicle, the upgrade is essential, not optional.

Does the NOCO GB40 work in cold weather?

Yes, better than the GB20. Both are rated for cold weather use, but the GB40’s larger 15Wh battery holds more effective cranking power when temperatures drop and lithium cells lose efficiency. In sub-freezing conditions, the GB40’s extra reserve makes a real difference. Warm the unit indoors for 30 minutes before use in extreme cold for best results.

How many times can I use the GB40 before I need to recharge it?

NOCO rates both the GB20 and GB40 for up to 20 jump starts on a single charge under normal conditions. In cold weather or on large engines, expect fewer attempts per charge. Recharge after every use to keep it ready for the next emergency.