GOOLOO GT4000 4000A Jump Starter & 20,000 mAh Power Bank, 12V

Big Diesel, Flat Battery, Long Way from Help.

Most small jump packs are sized for a hatchback. Clip one onto a big 4WD diesel on a frosty morning and the starter groans, slows and stops — and you are back where you began, with a flat battery, no second vehicle and either a long walk or an expensive tow. On a station track or a beach run with no bars, that is half the day gone before it has started.

The GT4000 is a bigger lithium pack built for that job. The maker rates it to 10 litres diesel and 12 litres petrol, and between starts it works as a 20,000 mAh power bank for the phone, tablet or laptop. It lives behind the seat and does nothing until the morning it saves you the tow.

What it Does

Two jobs in one box. Clamp it on and it starts a flat 12 V battery without a second vehicle, with a screen showing charge left, what it is doing and an error code if something is wrong. The rest of the time it is a power bank: two USB-A ports and a USB-C port that charges at up to 100 W in both directions, plus a DC output. There is also a 400-lumen LED with steady, strobe and SOS modes for working in the dark or flagging someone down.

Key Features

• Rated for Big Engines: the maker rates it to 10 litres diesel and 12 litres petrol, so it covers the big 4WD and ute diesels, not just the family car.
• 800 A for 3 Seconds: the maker's starting-current figure, which is the one that turns an engine over. The maker's 4000 A is the peak.
• Pre-Heat for Cold Starts: the unit carries a low-temperature heat badge, and the maker says it warms its own pack so it can start a vehicle at down to −40 °C.
• 20,000 mAh Power Bank: USB-C at up to 100 W in and out, one USB-A quick-charge port (5, 9 or 12 V) and one USB-A at 5 V / 2.4 A.
• Quick to Top Up: the maker says 0 to 100 % in about 1.2 hours on a 100 W USB-C charger, and that 5 minutes on charge gives it enough for a jump.
• 81 mm (3.2 in) Screen: battery level, status and error codes at a glance, so you are not guessing whether it is ready.
• 10 Protections, by the Maker's List: reverse polarity, reverse charge, short circuit, over-current, over-voltage, over-load, over-charge, high and low temperature, and a software check.
• Holds its Charge: the maker says up to 18 months between charges on the shelf. We would still check it every few months.

Limits

The engine ratings are the maker's, and they are best-case numbers. GOOLOO rates the GT4000 to 10 litres diesel and 12 litres petrol. We have not tested that. A cold morning, a battery that is completely dead rather than just low, a tired starter motor or a half-charged pack all pull the real figure down. If your engine is near the top of that range, keep the pack fully charged and give it every chance.

• 4000 A is a Peak Figure, Not a Sustained One: maker stated. It is the instant of cranking, not what the pack delivers continuously. The maker's 800 A for 3 seconds is the more useful number.
• 12 V Only: this will not start a 24 V truck, bus or machinery system.
• No Water Rating We Can Confirm: none is shown on the unit in the maker's photos, so we do not publish one. Treat it like any other electronics and keep it dry.
• Pre-Heat is the Maker's Claim: starting at down to −40 °C is GOOLOO's figure. The test conditions behind it were not supplied, and we have not tested it.
• Do Not Leave it in a Hot Cab: this is a lithium pack. A closed vehicle parked in direct sun in an Australian summer gets well past what lithium cells should sit at. Store it charged, out of the sun, and take it out of the cab in a heatwave.
• Check it Every Few Months: whatever the shelf-life claim, a jump starter you have not charged since last winter is a paperweight when you need it.
• No Wall Charger in the Box: the maker's in-the-box picture shows leads and cables but no mains plug. To get the 100 W charge rate you need a USB-C charger that can supply 100 W; a small phone charger will take a lot longer.
• Clamps the Right Way Round: red to positive (+), black to negative (−), and follow your vehicle maker's jump-start instructions in the owner's manual. The maker lists reverse-polarity protection; do not rely on it.
• Not a Glovebox Pack: about 1.5 kg and 230 × 100 × 54 mm. It belongs behind the seat or in the drawer system, not the glovebox.

Q & A

Will it Start my Diesel 4WD?
Check the engine size in your owner's manual. If it is under 10 litres diesel or 12 litres petrol, it is inside the maker's rating — and the closer you are to that number, the more it matters that the pack is fully charged.

Will it Start a Truck or Tractor?
Only if it runs a 12 V system. Anything on 24 V needs a 12 V/24 V jump starter; this is the wrong tool.

How Long does it Take to Recharge?
The maker says about 1.2 hours from empty on a 100 W USB-C charger. No wall charger is shown in the box, so use one you already have that can supply 100 W, or expect it to take longer.

Can I Charge my Laptop from it?
If your laptop charges by USB-C, yes — the USB-C port puts out up to 100 W, by the maker's figure. Phones and tablets run off the USB-A ports as well.

Can I Leave it in the Ute All Summer?
We would not. Lithium does not like heat, and a parked vehicle in an Australian summer gets a long way past comfortable. Keep it charged, out of direct sun, and bring it inside when it is severe.

What Comes in the Box?
Going by the maker's picture: the GT4000, the clamp leads, a car-socket plug lead, two USB cables, a DC-to-car-socket adaptor, a drawstring bag and a quick reference guide.

Specs

Ships from an Australian warehouse. Free Standard Delivery: allow 5 to 10 working days from the day you order. Allow 1–2 days for fulfilment.