NOCO GB40 vs GBX45: Classic Pack or USB-C Fast Charging?

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The GB40 is NOCO’s classic compact jump starter. The GBX45 is its newer “Boost X” replacement in the same size class. On paper the GBX45 wins almost everywhere: more peak current, a higher engine rating, USB-C fast charging and a laptop-capable power bank. But one number goes the other way, and it matters for how you will actually use the pack. This comparison explains the trade-off and tells you which one fits your habits.

NOCO GB40 vs GBX45: Side-by-Side Specs

Engine Coverage

The GBX45 is rated for gas engines up to 6.5L and diesels up to 4.0L, a step above the GB40’s 6.0L gas and 3.0L diesel. For most cars it makes no difference; both cover four-cylinder and V6 engines with room to spare. The extra margin helps if your engine sits near the GB40’s limit or you own a light diesel, where the GB40 is right at its 3.0L ceiling.

Winner: GBX45, by a small margin.

Starts per Charge: The GB40’s Big Advantage

This is the number that surprises people. NOCO rates the GB40 for up to 20 starts per charge but the GBX45 for up to six. The GBX45 delivers its energy at higher voltage for stronger individual starts, and a 60-second timer manages that output, but its total reserve is smaller.

What this means in practice: if you tend to leave a jump pack in the car for six months and only think about it when the battery dies, the GB40 has more in the tank. If you charge your gadgets often, six starts is plenty, because you will rarely need more than one or two before you can recharge.

Winner: GB40.

Charging: The GBX45’s Big Advantage

The GBX45 recharges in about 48 minutes over USB-C Power Delivery, compared with about three hours for the GB40 on its older port. NOCO also says five minutes of charging gives the GBX45 enough power for one jump, even from empty. That is a real safety net: if you discover the pack is flat, plug it into a USB-C charger or a car’s USB-C port while you wait, and you can still get going.

USB-C also means you probably already own a charger and cable that fit, which makes it more likely you will actually keep it topped up.

Winner: GBX45, clearly.

Power Bank

The GBX45’s USB-C port works in both directions at up to 60W. That is enough for most phones at full speed, tablets and many laptops. The GB40’s USB output handles phones and tablets but not laptops. If you would use the pack as a travel power bank, that alone may decide it.

Winner: GBX45.

Safety, Size and Light

Both are spark-proof and reverse-polarity protected, so a wrong connection does nothing. The GBX45 uses NOCO’s newer UltraSafe 2.0, which adds better thermal management for its high-voltage output. In daily use, both are equally foolproof. They are almost the same weight (about 2.5 to 2.6 lb), both fit a glove box, and both have a 100-lumen, seven-mode LED.

Winner: Tie.

Which One Should You Buy?

Three Real-World Scenarios

The glove-box-and-forget driver

You put a jump pack in the car and may not think about it until the battery dies next winter. The GB40’s larger reserve (up to 20 starts per charge) gives you more margin after months of self-discharge, so it is the safer choice here, as long as you still try to top it up a couple of times a year.

The commuter who charges everything over USB-C

Your phone, laptop and earbuds all charge from USB-C, and you have a USB-C port in the car. The GBX45 fits your routine: plug it in on a drive for half an hour and it is full. The 60W output also makes it a useful travel power bank.

The weekend road-tripper

You want a pack that also keeps a laptop or tablet alive on the road. The GBX45’s 60W USB-C output wins, and its five-minute emergency charge is a good safety net if you forgot to top it up before leaving.

How Long Will Each Last?

Both use lithium cells, which age with time, heat and charge cycles. How you store the pack matters more than which model you buy. Keep it out of direct sun, avoid leaving it fully drained, and recharge after each use. A pack that is kept charged and stored in moderate temperatures will usually stay useful for years. If a pack swells, gets unusually hot while charging, or no longer holds a charge for more than a few weeks, stop using it and replace it.

What About Bigger Engines?

Neither pack is meant for V8 trucks or larger diesels. If you drive one, compare the NOCO GB70 or see our guide to the best jump starters for diesel trucks.

The Verdict

For most people in 2026, the GBX45 is the better everyday pack. USB-C charging in under an hour, the five-minute emergency charge and laptop-capable output make it easier to keep ready, and its rating is slightly higher. The GB40 still makes sense for one kind of owner: someone who wants to put a pack in the glove box and not think about it, where 20 rated starts per charge provide more reserve.

Whichever you pick, recharge it after each use and every two to three months in storage. Read our full NOCO GB40 review, or see how both compare with other brands in our portable jump starter roundup.

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• NOCO Boost GB40 review
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