Watch It in Action

NOCO Boost Plus GB40 jump-starter demonstration.

Watch on YouTube ↗

Our verdict: ✓ KEEP

Research supports the GB40 for drivers who want a small emergency jump starter that can stay in the vehicle without taking up much room, provided their engine falls within its rated size.

KEEP if

You want a compact 12-volt lithium jump starter for occasional dead-battery emergencies. NOCO rates the GB40 at 1,000 peak amps for gasoline engines up to 6.0 liters and diesel engines up to 3.0 liters.

Know before buying

Car and Driver found the leads short and the clamps difficult to squeeze. Its test also showed the compact pack stores less energy than larger models; a severely drained battery used much of the available charge. Drivers who expect repeated jumps or need extra capacity should consider a larger unit.

Why it earns a KEEP

It addresses a real roadside problem in a compact package. The independent test found it capable of starting a car during emergency use, while its small size and straightforward controls make it practical to carry. The capacity trade-off is real, so it is best viewed as an occasional-use backup.

Research sources

• NOCO — GB40 product information and specifications
• Car and Driver — 2026 portable jump-starter testing

Engine ratings and device specifications are manufacturer information. Portability and emergency-use observations above are based on the independent test; The Keep Test did not personally test this model.