NOCO GB40 vs GB70: which jump starter does your engine need?

This comparison is built from NOCO's own figures as listed on Amazon.co.uk and from owner reviews. We have not tested either unit ourselves. Both are lithium jump starters from the same Boost range, with the same safety features, so the decision comes down to engine size, weight and how often you expect to use it.

Specs side by side

The differences that matter

Engine size is the deciding spec

The GB40's 3.0-litre diesel ceiling is the line to check first. It comfortably covers a 1.0-litre petrol Fiesta, a 1.3-litre petrol Qashqai or a 2.0-litre diesel Transit Custom. It does not cover larger diesels: an older 4.4-litre V8 diesel Range Rover or a big-engined pickup is outside the GB40's rating and inside the GB70's 6.0-litre one. Find your engine size on the V5C logbook if you are unsure.

Petrol engines are rarely a problem. The GB40's 6.0-litre petrol rating is above almost every petrol car sold new in the UK.

Starts per charge and margin

The GB70 claims up to 40 starts per charge against the GB40's 20. For a single household car that difference rarely matters, because you will use it a handful of times a year. It matters more if you look after several vehicles, a classic that sits all winter, or a motorhome on a campsite where a second car is not to hand.

Weight and where it lives

The GB40 is listed at about 2.5 lb and NOCO pitches it as glovebox sized. The GB70 is about twice that, at 5.0 lb, so it is more of a boot or door-bin item. If the jump starter is going in an emergency kit that also holds a warning triangle and a first-aid kit, the smaller one keeps the kit compact.

Torch and recharge time

The GB70's 400-lumen torch is four times the GB40's listed 100 lumens, which helps when you are lifting a bonnet on an unlit lay-by. The trade-off is recharge time: 6 hours for the GB70 against 3 hours for the GB40, per the listings.

Pick the GB40 if...

• Your car is petrol, or a diesel of 3.0 litres or less.
• You want it to live in the glovebox or a compact emergency kit.
• You only need it for one or two household cars.

Pick the GB70 if...

• You drive a diesel above 3.0 litres, or a petrol above 6.0 litres.
• You maintain several vehicles, or a van, motorhome or tow car.
• You want the brighter 400-lumen torch and more starts per charge.

Still deciding whether you need a jump starter at all? Readjump starter vs jump leads, see what else belongs in the boot in ouremergency kit essentials guide, or browse our emergency kit picks. More on the brand at NOCO, and if you are weighing a cheaper rival, seeNOCO GB40 vs GOOLOO GP4000or our GB40 review.

Frequently asked questions

Will a NOCO GB40 start a 2.0-litre diesel?

Yes, on paper. NOCO rates the GB40 for petrol engines up to 6.0 litres and diesel engines up to 3.0 litres, so a 2.0-litre diesel sits inside the rating. That covers the diesel engines in most UK family cars and vans such as the Ford Transit Custom.

When do I actually need the GB70 instead of the GB40?

When your engine is outside the GB40 rating, or close to its edge. The GB70 is rated for petrol engines up to 8.0 litres and diesels up to 6.0 litres. If you run a diesel above 3.0 litres, such as an older 4.4-litre V8 diesel Range Rover, the GB40 is outside its rating and the GB70 is the one to buy.

What does 'up to 20 starts per charge' mean?

It is NOCO's claim for how many jump starts a fully charged unit can deliver before it needs recharging. The GB40 is listed at up to 20 starts and the GB70 at up to 40. Real numbers depend on the engine, the temperature and how flat the battery is, so treat them as a ceiling rather than a promise.

Can either one charge my phone?

Yes. Both listings describe a built-in power bank for phones and tablets, and both ship with a USB-C charging cable. The GB40 is listed as recharging in 3 hours and the GB70 in 6 hours.

Is a jump starter better than jump leads?

A jump starter works without a second car, which is the main reason to carry one. Jump leads are cheaper and never need charging. See our jump starter vs jump leads explainer for the full trade-off.