AS YOU MIGHT KNOW, I LIVE IN AN AMBULANCE. It’s based on a Chevrolet truck with a 6.6 liter Duramax diesel engine. It’s a fantastic engine, but my batteries have died on it. I think they were just old when I got the truck. They were struggling and I was in the middle of nowhere when they finally died. So, until I got new batteries, I had been jump starting the ambulance with a GOOLOO GP4000 that belongs to a friend. It worked so well I went ahead and got my own.

My engine is enormous, and none of you are going to have an engine that’s harder to start unless you’re driving a tractor trailer or big diesel pusher motorhome. GOOLOO says the GP4000 will start all gas engines and up to a 10 liter diesel engine.

The Specifications

4,000 Amps peak current

Up to 60 jumps per charge

Overcurrent protection, overload protection, over-voltage protection and overcharge protection

USB-C Input and Output (5V/3A)

Dual USB charge ports (one compatible with fast charging)

12V accessory outlet

USB-A wall charger and cables

It comes in this really nice case. Packaged on one side are the jumper cables and charging cables. On the other side is the actual unit. 

It says to fully charged before you use it the first time. When I push this button it shows the charge meter and, at the moment, right out of the box, it shows it’s three-quarters charged. I have never gone below three bars when using my friend’s GOOLOO, and it fully recharges in less than an hour with a USB-C charger. 

The jumper cables might seem short, but they’re long enough because you put the charger right by the battery. There’s only one way to attach the cables to the GOOLOO, so you can’t get it wrong.

There’s a button on the jumper cable plug. It’s a boost button for cold engines or large diesel engines. My engine will barely crank over if I haven’t pushed the button, but it starts right up if I have. 

The 5V/3A USB-C port is good for charging the GP4000 or for using the GP4000 to charge other items. There are also two USB-A ports and a connector for a 12V accessory outlet. That means you can use this jump starter like a very large portable battery pack—4000 Amps versus 20,000 milliamps. I love that.

the GOOLOO GP4000 also has a very bright flashlight so you can see what you’re doing under the hood. It has an emergency flasher setting or can be set to flash and S-O-S signal.

Let’s test it

I started with nearly dead batteries. All I got was a click-click-click when I turned the key. So I clipped the GP4000 to the battery terminals — red to positive, black to negative — then turned it on, pushed the boost button (since I was trying to start a diesel engine) and waited a few moments while the batteries drew some current from the GOOLOO. Then, when I turned the key, vroom, it started right up. No problem. That had always been my experience with this jump starter.


I give the GOOLOO GP4000 my highest recommendation. Not only does it reliably jump start even big stubborn diesels like mine, it makes a great portable power pack for other devices. That means it’s more than one of those emergency items you hope you never need to use.

Do you need a jump starter as large as the GP4000 if you have a smaller engine. Maybe not, but if you had it you’d be able to help someone who did have a big engine.