CTEK RB 4000 Jump Starter review
CTEK RB 4000 Portable Jump Starter - 4000A Battery Peak Current
By Tom Calder
The RB 4000's headline 4000A is a marketing peak figure — the real-world number is the 2060A maximum cranking current, still a credible step up from CTEK's own RB 3000. It's expensive for a lithium jump pack, so it earns its price on engineering and warranty rather than the badge number; like any lithium pack, store it indoors rather than in a hot car boot or a freezing shed.
- Best for
- Drivers with larger engines or frequent breakdown-cover-style use who want CTEK's build quality and 2-year warranty, not just a cheap booster.
- Skip it if
- You only want an occasional emergency booster for a small petrol car
as of 5 Nov 2026, 22:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.We earn a commission if you buy through the retailer links on this page. It doesn't change our verdict. How we make money →
Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Genuine reverse-polarity and spark-proof protection from an established 12V specialist (CTEK), not just a marketing claim
- Doubles as a real power bank (USB-A QC3.0 + USB-C PD30W) and 3-mode LED torch
- 2-year warranty and UK support/spares via CTEK's own store
Worth knowing
- It costs 3-4x a NOCO or GOOLOO booster with broadly similar real cranking output
- CTEK doesn't publish a litre-based engine limit, so buyers must judge fit from the 2060A cranking figure rather than a simple 'fits my car' claim
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Our review
CTEK's larger lithium booster: an 88.8Wh pack that CTEK rates at 2,060A of maximum cranking current and up to 45 starts from one charge, with a 30W USB-C power bank built in. The figure to buy on is that cranking current, not the 4,000A printed on the box. It suits owners of big diesels, vans and motorhomes, and anyone who ends up starting other people's cars every winter.
What the numbers mean
CTEK publishes three current figures for the RB 4000. The 4,000A battery peak current is the headline. The start current is up to 1,300A, and the maximum cranking current, the highest figure CTEK gives for turning an engine over, is 2,060A. That shows how close this unit sits to its smaller sibling, the CTEK RB 3000, rated at 1,980A. The gap is 80A; what you are mostly paying for is a bigger battery and more attempts.
Inside is a 24,000mAh polymer lithium-ion pack, 88.8Wh, rated for 500 charge cycles. CTEK quotes up to 45 starts on one charge, and its support site adds that big engines and cold temperatures bring that number down. CTEK's product page now puts the engine ceiling at up to 10L petrol and 8L diesel and pitches it at workshops, fleets and recovery.
On the road, in a British winter
The practical question is whether the pack is charged and in the car on the first frosty morning. CTEK says the RB 4000 holds its charge for up to six months, and its manual asks you to recharge it regularly, so a reminder when the clocks change covers it. It is rated to jump start from -20°C to +55°C, though CTEK's support site notes that cold weather and large engines both cut the number of starts. The manual asks for no more than three attempts in a row, with five minutes between them, so the pack does not overheat. CTEK lists it at 1.21kg and 239 by 107 by 40mm. The connection order, and when not to try at all, are in how to jump start a car.
How it compares
The NOCO Boost GB150 is the rival at this size: 3,000A peak, rated for petrol engines to 9.0L and diesels to 7.0L from an 88Wh battery almost identical to CTEK's, but 2.9kg against 1.21kg and only a 10W USB-C charge. The NOCO Boost X GBX75 is 1.71kg, rated for 8.5L petrol and 6.5L diesel from 74Wh, and refills in 1.7 hours over 60W USB-C. CTEK's edge is that it tells you its cranking current; NOCO gives peak amps and engine sizes but no cranking figure. The rest of the field is on our jump starter comparison.
Living with it
Charging is through USB-C Power Delivery at 30W, and CTEK quotes 3.5 hours to full. Its manual says the mains adapter is sold separately, so budget for a 30W USB-C charger if you do not own one. As a power bank it offers USB-A Quick Charge 3.0, USB-C PD at 30W and a 12V output, and the LED torch has standard, strobe and SOS modes. The case is IP65 only with every port closed; the manual says the rating no longer applies while it is charging or connected for a start. The warranty is two years, and CTEK answers questions through its own support site.
Safety and storage
CTEK's manual gives a storage range of -20°C to +50°C with a daily average of 0°C to +25°C, a charging window of 0°C to 45°C, and says not to keep it in direct sunlight or heat, which rules out a parcel shelf in July. Keep the pack indoors between journeys and put it in the car for winter trips. Reverse-polarity protection and spark-proof technology are built in, and CTEK says never to charge or start a frozen battery; our lithium battery fire safety guide covers lithium at home. A second flat morning in a week is a job for a garage or a battery charger and maintainer.
Our verdict
Buy the RB 4000 if you run a large diesel, a van or a motorhome and want CTEK's stated 8L diesel rating, more attempts per charge and a two-year warranty from a 12V specialist. Choose the RB 3000 instead if you drive an ordinary petrol car: the cranking current is nearly identical and the pack is lighter. Look at the NOCO GBX75 if fast charging and a pack that can run a laptop matter more to you.
A researched review, built from the maker's specs, manual and UK listings; facts checked 21 Oct 2026. Sources: CTEK — RB 4000 product page and specifications; CTEK — RB 4000 user manual (storage and charging temperatures, IP65 conditions, start limits); CTEK support — How many starts on a single charge (RB 3000 / RB 4000); CTEK Magazine — Portable jump starters: how to choose (charge retention up to six months).
Who shouldn't buy this
Don't buy this if you only want an occasional emergency booster for a small petrol car — a NOCO GB40 or GB70 does the same job for a third of the price. The RB 4000 makes sense for larger diesels, frequent use, or if CTEK's warranty and support matter to you.
Key specs
| Peak current | 4000A peak |
| Engine coverage | No litre-specific claim published by CTEK |
| Capacity | 24,000mAh / 88.8Wh lithium-polymer |
| Extras | USB-A + USB-C power bank output |
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
If this isn’t the one
Best for A compact glovebox backup that gets a flat petrol car or small diesel going without waiting for a breakdown van.
as of 5 Nov 2026, 22:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Drivers who need to cover a bigger diesel - a van, 4x4 or larger family car - as well as ordinary petrol cars, in a pack that still fits in a glovebox.
as of 5 Nov 2026, 22:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Drivers who want one mid-size jump starter that covers most family cars and small diesels, rather than buying NOCO's biggest (and priciest) unit just in case.
as of 5 Nov 2026, 22:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Questions
Can the CTEK RB 4000 start a diesel?
CTEK's product page now says the RB 4000 is built for up to 10L petrol and 8L diesel engines. Its support site adds that large engines and cold temperatures reduce the number of starts from the quoted 45, so expect fewer retries on a big cold diesel.
How long does the CTEK RB 4000 take to charge?
CTEK quotes 3.5 hours from a 30W USB-C Power Delivery charger. A lower-powered phone charger works but takes longer, and CTEK publishes no time for that.
Can I leave the RB 4000 in the car?
For a winter journey, yes. Long term, no: CTEK's manual sets a daily average storage temperature of 0°C to +25°C and warns against direct sunlight and heat, so a summer car falls outside it. Store it indoors and charged; CTEK says it holds that charge for up to six months.
Does the RB 4000 work as a power bank?
Yes. It has USB-A Quick Charge 3.0, a 30W USB-C Power Delivery port and a 12V output from an 88.8Wh battery, under the 100Wh limit the CAA applies to power banks in hand luggage; check with your airline.
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