NOCO GB40 vs GBX45 (2026): Which Jump Starter Is Best?

NOCO Boost GB40 vs GBX45 (2026): Hands-on comparison of two popular 12V lithium jump starters. We tested ports (USB-C vs USB-A), clamps, indicators, flashlights, and usability so you can choose the right pack for your car, truck, SUV, or boat.

Last updated: September 16, 2026

In this article I compare the NOCO Boost X GBX45 (1250A) and NOCO Boost Plus GB40 (1000A) after physically testing both units on vehicle batteries and checking their ports, clamps, displays, indicators, flashlights, and day-to-day usability. The key difference is not just peak amps: the GBX45 adds a larger diesel-engine rating and 60W USB-C Power Delivery, while the GB40 covers most everyday vehicles at a lower price.

Disclosure: We may earn a commission from qualifying purchases made through Amazon links in this article. As an Amazon Associate I earn from qualifying purchases.

Table of Contents

• 🔋 Quick summary
• ⚙️ Design and ports
• 🧰 Clamps, connectors, and jump procedure
• 💡 Display, safety indicators, and boost mode
• 🔦 Flashlight and other practical features
• 📏 Size, weight, and carry case
• 🧾 Who should pick which model?
• ✅ Final thoughts
• ❓ FAQ

🔋 Quick summary

The GB40 and GBX45 are both compact 12V lithium jump starters that double as USB power banks. Here’s what actually separates them:

• Power: GBX45 = 1250 amps; GB40 = 1000 amps.
• Charging: GBX45 uses USB-C in/out (USB-C Power Delivery — a fast-charging standard up to 60W); GB40 uses USB-C input (recharge) and USB-A output for devices.
• Display & indicators: GBX45 has a more detailed LED display and status icons (temperature, reverse polarity, fast charge), while GB40 has a simpler fault LED and basic charge LEDs.
• Size & weight: The GB40 is longer and thinner (7.72 × 3.16 × 1.71 in), while the GBX45 is shorter and thicker (6.83 × 3.28 × 2.08 in). NOCO’s current web specs list 2.45 lb for the GB40 and 2.16 lb for the GBX45.
• Battery compatibility: Both are designed to jump-start 12V lead-acid batteries; neither is a car-battery charger.

📊 Side-by-side comparison table

Verified spec sources: NOCO GB40 specifications and NOCO GBX45 specifications. NOCO’s current GBX45 web page lists 2.16 lb; an older 2024 NOCO datasheet lists 1.3 lb, so this comparison uses the current web specification.

Deal tip: Shopping for the GB40 this month? It's one of our top picks in the best October Prime Day car deals, alongside the GOOLOO A3 and AstroAI S8, during Prime Big Deal Days on Oct 6–7.

⚙️ Design and ports

Both units are IP65-rated with the port covers closed and have dense, rigid housings. In hand, the most useful design difference is the charging layout: the GBX45 supports up to 60W USB-C Power Delivery in and out and also retains a 10W USB-A output, so it can recharge quickly with a compatible 60W charger and power USB-C devices such as laptops.

The current GB40 charges via USB-C input at up to 5V/2.1A and outputs via USB-A at 5V/2.1A. It works well as a phone/tablet power bank, but it does not provide the GBX45’s 60W USB-C output.

Port note: Current-production GB40 documentation lists USB-C input, but older GB40 manuals show micro-USB input. If you are buying used or old stock, check the physical charging port before ordering a replacement cable. The GBX45 supports 60W USB-C Power Delivery in and out.

🧰 Clamps, connectors, and jump procedure

The clamp connection is shared across these two models. NOCO lists its GBC003 HD Precision replacement clamps as compatible with both the GB40 and GBX45, which confirms official cross-model clamp compatibility. The connector only fits one way and should be pushed in firmly.

How to use (step-by-step):

1. Plug the clamp cable into the pack (align the arrow; it only goes one way).
2. Attach the red clamp to the positive battery terminal. Attach the black clamp to the negative terminal or an approved vehicle chassis ground, following your vehicle owner’s manual.
3. Turn the jump starter on and then start the car.

Important: The GBX45 gives you a 60-second jump-start window after you press the power button. If you do not start the vehicle in that window, the jump-start sequence times out; power the unit off and back on to reset it before trying again.

💡 Display, safety indicators, and boost mode

The GBX45 includes a more informative LED cluster and status icons: reverse polarity indicator, a snowflake for ‘too cold’ warnings, a thermometer for ‘too hot’, and a fast-charge indicator for USB-C charging. That extra feedback can save time and prevent misuse.

The GB40 keeps things simpler with a single fault indicator, while the GBX45 separates reverse-polarity, hot, cold, fast-charge, and other status feedback. Both units also have manual override for a 12V lead-acid battery that is too low for the jump starter to detect normally.

Manual override does not provide extra starting power. It forces the jump function on when battery voltage is too low to be detected (NOCO cites below 2V as the typical case). Hold the override button for about three seconds to engage it. This mode disables safety protections; on the GB40, NOCO specifically warns that spark-proof and reverse-polarity protection are disabled. Use it only when you have confirmed correct polarity and understand the manual’s safety procedure. See NOCO’s GBX45 manual-override guidance.

🔦 Flashlight and other practical features

Both models include a 100-lumen LED flashlight with seven light modes, including multiple brightness levels, SOS, blink, and strobe. That makes either unit useful for nighttime roadside work as well as jump-starting.

📏 Size, weight, and carry case

The GB40 is longer and thinner at 7.72 × 3.16 × 1.71 inches, while the GBX45 is shorter and thicker at 6.83 × 3.28 × 2.08 inches. NOCO’s current web specifications list the GB40 at 2.45 lb and the GBX45 at 2.16 lb, so the GBX45 is not the heavier unit despite its thicker body. Both include a microfiber storage bag for the unit, clamps, and charging cable.

🧾 Who should pick which model?

Choose the GB40 if value and basic emergency use matter most

Best for: Most cars, crossovers, SUVs, and light trucks within NOCO’s 6.0L gas / 3.0L diesel rating.

• Pros: Lower current NOCO price, 1000A peak rating, USB-C input on current units, 100-lumen flashlight, IP65 protection with ports closed, and the same one-year warranty.
• Trade-offs: Slower 5V/2.1A recharging, USB-A device output only, simpler status feedback, and a lower diesel-engine limit.

Verdict: If your engine is comfortably inside the GB40’s rating and this pack will mostly stay in the car for emergencies, the GB40 gives you the core jump-starting features without paying for 60W USB-C PD.

Choose the GBX45 if charging speed or diesel headroom matters

Best for: Drivers who need up to 6.5L gas / 4.0L diesel coverage, want a faster recharge, or expect to use the pack as a higher-output USB-C power bank.

• Pros: 1250A peak rating, 31Wh internal battery, 60W USB-C PD input/output, 10W USB-A output, more detailed status indicators, and a 60-second jump-start timer.
• Trade-offs: Higher purchase price and the 60-second timeout means you may need to power-cycle the unit if you wait too long before cranking.

Verdict: The GBX45’s biggest real-world upgrade is not the extra 250 peak amps by itself; it is the combination of higher diesel coverage, much faster USB-C recharging, and clearer status feedback.

Choose neither if your engine exceeds the GBX45 rating

If your engine is larger than 6.5L gas or 4.0L diesel, move up the NOCO range instead of assuming manual override will compensate. NOCO currently rates the GB50 up to 7.0L gas / 4.5L diesel, with larger Boost and Boost X models above that. For a broader lineup comparison, see our tested jump starter roundup.

If you want to see product specs or purchase, here are the Amazon product links:

Check price on Amazon — NOCO GB40
Check price on Amazon — NOCO GBX45

✅ Final thoughts

For most drivers, the decision comes down to engine size and charging needs. The GB40 is rated for up to 6.0L gas / 3.0L diesel and keeps the lower purchase price. The GBX45 raises that to 6.5L gas / 4.0L diesel and adds 60W USB-C Power Delivery, a 31Wh battery, and more detailed status indicators. If your vehicle fits comfortably within the GB40’s range and you mainly want emergency jump-start capability, the GB40 is enough. If you value faster recharging, USB-C device power, or the extra diesel headroom, the GBX45 is the stronger fit.

❓ FAQ

Will either of these start my car?

Use your engine size and battery type as the first filter. NOCO rates the GB40 for 12V lead-acid vehicles up to 6.0L gasoline or 3.0L diesel, and the GBX45 up to 6.5L gasoline or 4.0L diesel. A compatible rating does not guarantee every start if the battery is damaged, frozen, or the vehicle has another fault.

How do I charge the units?

The GBX45 charges through USB-C and supports up to 60W USB-C Power Delivery input and output; NOCO says a compatible 60W charger can recharge it in about 48 minutes. Current GB40 units charge via USB-C input at up to 5V/2.1A and provide USB-A output for devices. Older GB40 documentation shows micro-USB input, so check the physical port on used or old-stock units.

What is boost mode and when should I use it?

Manual override is for a 12V lead-acid battery whose voltage is too low for the unit to detect normally. It does not add extra power; it forces the jump function on and disables safety protections. Hold the override button for about three seconds only after confirming correct polarity and following the NOCO manual.

Can I use the clamps from one model on the other?

NOCO officially lists the GBC003 HD Precision replacement clamps as compatible with the GB20, GB40, GB50, and GBX45. That confirms the GBC003 replacement clamp module can be used with either the GB40 or GBX45.

Does the GBX45 turn off automatically?

The GBX45’s jump-start sequence times out after 60 seconds if you have not started the vehicle. Power the unit off and back on to reset the sequence, then try again.

What warranty do these units carry?

NOCO lists a 1-year limited warranty for both the GB40 and GBX45. Keep your proof of purchase and follow NOCO’s current registration and warranty instructions.

Can the GB40 or GBX45 charge my car battery?

No. These are jump starters, not car-battery chargers or maintainers. They can supply the burst of power needed to crank a compatible 12V lead-acid vehicle, but NOCO directs users to a battery charger/maintainer for actually recharging the vehicle battery.

What if my engine is larger than the GBX45 rating?

Do not use manual override as a substitute for a correctly sized jump starter. If your engine is above 6.5L gas or 4.0L diesel, move to a larger model that NOCO rates for your engine size.

Any other tips?

• Fully charge the unit before first use and check its charge periodically during storage.
• Keep the storage bag, clamps, and charging cable together so the kit is complete in an emergency.
• Never attempt to jump-start a damaged or frozen battery, and verify polarity before using manual override.