merlin12volt—February 7, 2024✓ Verified purchase
I bought the GT4000S because I have a Ford Excursion with the large 6.8L Ford that has sit in recent times because of surgeries. I inevitably forgot to unhook the battery and after many weeks of sitting, it runs the battery down. Most recently a door switch began acting poorly and caused the battery to drain quickly. 2 weeks post surgery and the battery read less than 3 volts on a DMM. Tried a traditional pack I have (Stanley MAXX 1000A) and it turned on the lights but never attempted to crank. The GT4000S however, was very easy to set up, with one connection to the unit and essentially two button pushes. Out of the box and to my surprise, it immediately turned over my engine and started my Excursion with little effort. Only took 3% from the batteries charge as well. The display is basic but gives pertinent information. The unit itself is ruggedly built and its features are pronounced. The USB-C connections will charge everything from a laptop to a phone with ease. It will vary the voltage based upon the need of what is being charged. For jump starting, it will not let you hook up the terminals incorrectly and will indicate to you that you have them incorrectly placed. It recharges quickly, but is limited in the USB-C to <50watts when not connected to a dedicated 100watt charger from GOOLOO, which more than doubles the 1.5 hours to over 3 hours from dead, but isn't a huge concern as I plug it in overnight after using it then place it back in my truck in the morning. Overall, I am impressed with this unit and cannot say enough about it. Its compact, comes with a charging cable (USB-C to USB-C) jumper cables, a carry case (nylon type of sack), and a hefty manual. Couple of tips, if it has trouble starting the car because the battery is drained to near zero, press the button once to put it in boost mode, and immediately start the vehicle. Invest in the hard case kit that is sold for them. Well worth it and ensures that screen is 100% protected. Read more
Kat—July 3, 2025✓ Verified purchase
Necessary for any car or RV and roadtrip. Just bought this for our son leaving for college. Almost everyone in our family carries a Gooloo in their car and have for last 7 years. We even used it recently to jump our $15K RV lithium battery bank. Easy to use, reliable, you're never stranded and always have power for phone charging, etc. They retain a charge for very long periods (my experience 2 years and more without recharge) and recharge quickly. A must for any loved one to keep them safe and independent. Faster to Gooloo jump a car than jumper cables- throw the cables away and don't wait for another vehicle to help. I use before calling AAA. Read more
Mark Getz—March 23, 2026✓ Verified purchase
This jump starter is GREAT! It’s slightly larger than others that I’ve seen, but that’s because it has 2-3 times the power of the others. It has started everything that I’ve used it on! I even use it to charge other power banks, because the fast charging cord that comes with it is amazing. It’ll recharge in minutes, not hours. Read more
Wolfking—December 27, 2023✓ Verified purchase
There is a version of this device that will pre-heat the device in extremely cold weather. Make sure that's what you get if you're in very cold places! This one does NOT have the heater and being in a car overnight in the 20s or below means it needs to warm up to about 50 before it will deliver full charge. Trying to jump with it before it warms up can damage the thing or it simply won't do anything at all. But, cold weather issues aside... it's a very good performer, jumps most anything the first time without any problems, even batteries that are so dead they won't even register as a circuit when the box is hooked up (digital display does not turn on to indicate it's detected a battery). For occasional use one will be good - just charge it up once very month or two (it'll loose less than 10% a month while in storage). If you use them daily like I do you'll want two or more. While very good they are very, very sensitive to overvoltage and will drop into safe mode very, very quickly and it takes upwards of 10 minutes before it'll reset itself. And they discharge relatively swiftly... 7 'dead' cars or 10 'weak' cars, at most, before they're below 20% charge where it'll begin to struggle. Type-C charger means it'll recharge *FAST* - about 90 minutes from 0 to 100% at a wall outlet with a decent outlet charger (20v min). 2+hrs with a standard car utility outlet (5v). Read more
Hunter House—September 22, 2025✓ Verified purchase
Works great. I bought 3 of them last year. Have jump started many things in the past year, 2 of them actually jump started a 24 volt 16.2L Liebherr engine. My only complaint is when it is overloaded it will flash an error code for overloaded and wont seem to reset until it sits for about 10 min. Does not feel hot or anything. This is a problem if you can not get something to start and youre cranking the engine for a while. Also ran into an issue once where the battery was so dead it would only stay running while the jump starter was on it. It only stayed on of about 10 sec at a time, not long enough to atleast get the truck off the trailer. With everything said im still very happy with the power of these jump starters and would buy again Read more