Which one should I buy for a diesel truck?

The GB40. It is rated for diesel engines up to 3.0L; the GB20 has no diesel rating. For a diesel above 3.0L, look at a higher-amp NOCO model.

Is the GB40 worth about $10 more than the GB20?

Yes if you own a V6, V8, or diesel. The extra 500 amps and the 6.0L gas limit cover engines the GB20 cannot start. For a small 4-cylinder car, the GB20 is enough.

Which lasts longer on a charge?

Both are rated for up to 20 jump starts per charge and hold charge for up to a year. The GB40's larger battery gives more reserve for bigger engines.

Can either charge my phone?

Yes. Both have a USB power bank port and a 100-lumen LED flashlight with 7 modes, including SOS and strobe.

Which is easier to keep in the car?

The GB20 is smaller and lighter. The GB40 is about 1,200 g and roughly 7-3/4 inches long, still small enough for a glovebox.

Do both have the same safety features?

Yes. Both use NOCO UltraSafe clamps with spark-proof connections and reverse polarity protection, so a wrong connection will not damage the unit.

NOCO Boost Plus GB40 Jump Starter vs NOCO Boost Sport GB20 Jump Starter

Buy the GB40 for anything with a gasoline engine over 4.0L or a diesel engine, and for the extra 500 amps of headroom. Buy the GB20 only if you drive a small gas car, motorcycle, or ATV and want to save money. As of November 8, 2026, the GB20 is $63.96 at Blain's Farm & Fleet and the GB40 is $74.00 at eBay, a gap of about $10.

Today the NOCO Boost Sport GB20 Jump Starter costs $10.04 less at its best price.

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