GOOLOO GT4000S Jump Starter 4000 Amp Car Starter 100W Two-Way Fast-Charging Portable Car Battery Charger Booster Pack for 10L Diesel and 12L Gas Engines, SuperSafe Lithium Jump Box for 12V Vehicles

My First Jump Pack – I Was Skeptical
I’ve been researching these compact jumper units for about a year, and they look pretty impressive – some better than others. But the price points – Oy vey! As sales went up the cost came down, Amazon offered this unit for 150 bucks. I jumped on it (pun intended). I was hopeful, but skeptical, this little box would deliver on the promise. But so far it appears to be everything the seller claims – and more. I’ve only had it for about a month and have yet to use it in an emergeny situation – but it seems capable.Was a little disappointed no hard case was included. However, the factory box it came in is built like a brick s***house. For long-term storage this container will work just fine. I’ll be keeping mine primarily in the door well of my truck, though. The unit with the cables was heavier than I expected, which I think is a good thing. The main case seems quite rugged and possibly waterproof as well. The display is excellent – very easy to read. A blessing for my tired old eyes. All functions are easy to access, and operation is quite intuitive. No one should have any trouble making it work. There are a couple things you need to know beforehand, so I’d suggest you [gasp!] parse the manual before going into combat. No worries – the instructions are short and sweet.My unit came 80% charged. This sounds about right for a Lithium Ion array (safety first). Tried the 5V USB port to charge it up – it worked, but it was waaay slow. Still, it’s nice to have that option in a pinch. But for fast charging, the included cigarette adaptor kicks butt (again, pun intended). As the photos show, I started at 80% when I plugged it into my truck (engine off). Charge rate showed 125 Watts – wow! Higher than Gooloo advertises. Charging really took off, and within 15 minutes was up to 90%. Another 10 minutes or so and it hit 99%. Not too shabby. at 99%, things slowed down quite a bit. That last 1% took about 12 minutes.Now for the real test – starting my truck with the battery disconnected. This is not recommended, except as a last resort. Some vehicle computers can go spastic doing this, and operating a running engine with the box connected can damage your alternator. BTW, this can also happen using standard jumper cables. I know my vehicle pretty well (2012 Chevy Colorado), and have previously tested the computer’s resilience by disabling the battery while running. But again, be careful. Many newer PCMs/ECMs are quite unforgiving. A word to the wise.The result: Started my cold engine (48 degrees ambient) in 2 seconds flat. Also fired up my yard tractor without the battery in 6 seconds. The tractor’s V-Twin engine is notoriously hard to start, even with a fully-charged battery. I’m looking forward to trying this on bigger engines, especially diesels, but for the time being this is all the testing I could do. The no-load potential of the Gooloo measured 16.2 Volts, which seems to be typical for these boxes according to the Project Farm guy and a few others. Doubtful that this voltage level will cause any problems with your computer or alternator.Only complaint I have is a minor one, nothing I can’t live with. The side input/output ports are grouped together and covered with a long, hinged rubber weathershield. Nothing wrong with that, except that when the jumper leads are plugged in the hinge stays open and all the ports are exposed to the elements. This could *potentially* allow moisture, rain, snow, beer, etc to infiltrate. Sure, in most cases this won’t be an issue, but for an otherwise well-engineered product this seems kinda cheesy. Maybe the next generation will address this.There you have it. So far, I haven’t unearthed a single major flaw in this device. Of course, durability can only be measured over time. Normally I wouldn’t award 5 stars to something still under warranty, but I’ll stick my neck out on this one. If it tanks, rest assured I’ll be back to let y’all know.

It works great and reliable.
This was a great purchase. I keep it in trunk always. Used it numerable times and even saved on warranty of a battery. Returned battery and they did not want to replace it until it died at their establishment and this unit boosted it and after their testing the battery was replaced. The cable length could be a little longer. It is easy to use pretty straight forward, and have used it to recharge phone a few times.

It works as advertised
This is a quality battery pack. Works well to jump start cars and garden equipment. Note however that it recharges fastest by using the included 12 volt cable plugged into your car while the car is running. It will charge from a USB source but it can take days to charge from a wall plug brick which isn’t even included in the package so have to use your own. So just charge it from your cars 12 volt socket while driving because that will top off the battery in 30 minutes or so.

The real deal authentic and original very good bought the first one and my friend took it then I bought the other for me.I charged 3 phone twice and used it to jump the car battery work perfect