Check the peak amps
For petrol engines up to 2.0L, 400–600A peak is plenty. Larger engines and diesels need 1000A or more. Always check your engine size before buying.
Our top picks
🥇 Best Overall
NOCO Boost Plus GB40 1000A
1000A peak, covers petrol engines up to 6L and diesel up to 3L. Spark-proof, reverse polarity protected. The most trusted name in jump starters.
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🥈 Best for Vans & 4x4s
NOCO Boost HD GB70 2000A
2000A peak, handles diesel engines up to 8L. Built for trucks, vans, motorhomes and large 4x4s.
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🥉 Best Budget
Portable Jump Starter 400A
400A peak, suits most small petrol cars. USB charging output. Fine for a runabout and significantly cheaper than the NOCO.
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Are portable jump starters safe?
Modern lithium jump starters have built-in protections against reverse polarity (connecting the clamps the wrong way), short circuits, and overcharging. Brands like NOCO include spark-proof technology so nothing happens until you turn the ignition.
They're genuinely safer and easier than traditional jump leads, which require a second vehicle and correct sequencing to avoid damaging either car's electronics.
Our verdict
The NOCO GB40 is the one to buy for most drivers. It's compact, reliable, and handles the vast majority of petrol and diesel cars on UK roads. The GB70 is worth the extra if you drive a large diesel or van.
Frequently asked questions
How long does a portable jump starter hold its charge?
Most good quality units retain usable charge for 6–12 months in storage. It's worth giving it a top-up charge every few months, especially before winter when flat batteries are most common.
Will a jump starter work on a completely dead battery?
Usually yes, but if the battery is deeply discharged some jump starters won't detect it and won't activate. NOCO units have an override mode for this situation.
Can I use a jump starter on a modern car with stop-start?
Yes. Modern cars with stop-start systems use AGM batteries, which are compatible with portable jump starters. Some NOCO units have a specific AGM mode.
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