INTRODUCTION

    Cars have a way of reminding us who’s really in charge, the morning you’re already late is the morning the battery decides it’s had enough, one or more tires quietly surrender overnight, and the whole day tilts off‑balance before it even begins. Modern vehicles are tougher than ever, yet the weak points remain the same—power fades, temperatures drop, and a dead battery can turn a simple errand into an unexpected crisis. That’s why compact jump starters have become essential gear, the kind of tool you hope you never need but feel strangely empowered just having in the trunk. Today I’m looking at two products that promise exactly that kind of confidence, the Gooloo A3 and GT4000S.

    Gooloo is a global leader in automotive solutions, specializing in high-performance lithium jump starters, smart power banks, and 2-in-1 air compressor tools. With over 5 million units sold across 160+ countries, Gooloo is trusted by drivers, mechanics, and outdoor adventurers alike. From everyday roadside emergencies to professional-grade fleet solutions, Gooloo products are designed to deliver unmatched safety, portability, and performance—anytime, anywhere.

    The Gooloo A3 centers its versatility around a 44.4Wh battery, delivering 3000A peak current, a 150 PSI tire inflator (5 modes), USB power outputs, and emergency LED lighting (400 lumen), all managed through a 3.2″ LCD screen that gives clear, real‑time status feedback. That energy reserve supports multiple jump‑starts and inflation cycles while handling engines up to 9.0L gas / 6.5L diesel. It’s also protected by a total of 10 built-in smart safety protections (over-charge, over-current, short-circuit, reverse polarity, AI software, high and low temp, spark-proof, over-voltage, over-load and reverse charge). The GT4000S doubles the capacity with an 88.8Wh battery, enabling its 4000A peak output, 100W bi‑directional fast charging, rapid 1.2‑hour recharge, 10 built-in smart safety protections (over-charge, over-current, short-circuit, reverse polarity, AI software, high and low temp, spark-proof, over-voltage, over-load and reverse charge), emergency LED torch (400 lumen) and laptop‑grade Type‑C power delivery. It also features the same 3.2″ LCD display (size-wise), but adds IP65 certification for dust and water resistance, making it the more rugged option for harsher environments. With support for 12L gas / 10L diesel engines and a 24‑month standby, it stands as the heavy‑duty, weather‑ready choice for drivers who want maximum power and durability.

SPECIFICATIONS AND FEATURES

PACKAGING AND CONTENTS

Both models arrive inside black boxes that have a product picture at the front alongside their main features and the company logo.

Peak current and engine compatibility are printed on the left side.

The product specifications can be found on the right side.

Proper usage instructions are printed at the rear of the box right over contact information for Gooloo.

Inside the box of the A3 we find a carrying/storage pouch, jump starter cable, tire pump tube, USB-C cable, 5 different air nozzles and the user manual while in the GT4000S box we find a storage/carrying bag, jump starter cables, cigar lighter adapter, USB-A and USB-C cables and the user manual.

THE A3

The 1Kg heavy A3 measures 150mm in length, 126mm in width and 59mm in thickness (the 5 control buttons are all on top).

The lower left side of the unit is perforated.

At the front we find the pump tube port, USB-A charging port, USB-C charging port, jumper cable port and the 400 lumen LED torch.

Gooloo has placed a rubber handle on the right side.

The product specifications and proper use instructions are printed at the base of the A3.

The 3.2” LCD screen includes information like the current battery charge, selected inflation mode and KPA.

Here you can see the A3 connectivity.

The bundled carrying/storage pouch may not be great but it’s still better than not at all.

THE GT4000S

The GT4000S also weighs 1Kg but measures 228mm in length, 100mm in width and 54mm in thickness (on/off and boost buttons are both on top).

Since this is an IP65 certified device all ports (jump starter, two USB-A, USB-C, DC) are located behind a rubber cover at the front.

The 400 lumen LED torch is placed at the rear of the unit.

Product specifications and error messages are all printed at the base.

As I mentioned before even though the A3 and GT4000S both have 3.2” LCD screens they are different with the one used in the GT4000S being easier to read under direct light.

Only the jumper cable attaches to the GT4000S when you need to start your car.

Since the GT4000S doesn’t come with a carrying/storage case in the bundle I strongly suggest ordering the hard EVA case from Gooloo seen above (provides even more protection and well, I think the GT4000S deserves it).

NOISE LEVELS

Not much I can test compressors/air pumps for so at least for now I'll be including noise levels from 15cm away.

CONCLUSION

    I may not have had many flat tires in my life but when it comes to car batteries, I’ve certainly had plenty of issues over the years. Now both Gooloo units do exactly what they promise, and that’s ultimately what matters most in a jump starter, they start cars reliably and consistently. The A3 brings solid functionality with its inflator and display, though I have to admit that its build feels a touch less premium next to the GT4000S’s heavier, more refined construction. It’s also worth noting that the A3’s built‑in compressor, while convenient, doesn’t inflate as quickly as traditional 12V cigar‑socket inflators, a small but expected trade‑off for having everything in one handheld unit. On the flip side, the GT4000S delivers the more rugged, high‑end experience but ships without a carrying case, so anyone who wants clean storage will need Gooloo's standalone EVA option showcased in this review. In the end, it’s a choice between all‑in‑one practicality and maximum power, and both deliver where it counts.

    This moment in time the Gooloo A3 retails for USD66.50/69.99Euros whereas the GT4000S retails for USD90.25/(not available in the EU) meaning they have different target audiences. Yes, both devices deliver as advertised but if you’re looking for the best jump starter of the two the GT4000S is it. Still if you need something that combines both a capable jump starter and a tire inflator the A3 is the way to go. So, even though Gooloo has better models in their lineup both come highly recommended and should have a permanent spot in every car.

PROS

- Jump Starting Capabilities
- Rubber Coated Battery Connectors
- IP65 Certified (GT4000S)
- Tire Inflator (A3)
- 3.2” LCD Screen
- LED Torch
- USB C 100W (GT4000S)
- Carrying / Storage Pouch (A3)
- Price (A3)

CONS

- Price (GT4000S)
- Inflate Time (A3)