GP4000: SuperSafe 4000A Jump Starter - 12V Car Battery Booster Pack | Lithium Jump Box with Jumper Cable - Spark-Proof - BOOST Button - LED Flashlight - For All Gas & 10 Diesel Engines

This is a long, involved Review. So... be patient. I bought this Gooloo unit exactly 30 days ago. Today provided my first opportunity to test it out. Background: I'm a 74 yr old Disabled/Retired Senior; confined to a wheelchair. I live off of my monthly SS check; so, limited income/essentially no savings. I live alone, ~ 60 mi. S. of Abq., NM; and make one errand run into Abq., each month - ~ 140 mi. round trip, with the around-town errands included. I put less than 1500 miles on my car, per year. I inherited the car when my mother died in 2010. The car is a 2002 Pontiac Bonneville; so, closing up on 21/22 yrs old. The stock battery lasted 15 yrs, but I've had ongoing dead-battery issues, since. I've put in four NAPA-grade batteries in the last 7 yrs, or so; two, new (at ~ $200 a pop), and two under limited warranty replacement (~ $80 a pop). The battery lives under the rear seat, and, what with the nature of my handicaps... it's pretty much a quite considerable pain for me to replace one. Over the last 7 yrs, the car has suffered from some sort of unidentified, intermittent drain on the bat, that deads it out maybe six to eight times a year. I suspect something like a malfunctioning trunk light switch, but have never been able to nail down the exact issue (I rmv'd the trunk lamp/bulb, but still have the issue; so... go figure). Anymore, I ck the battery once or twice a week; but still run into the dead bat issue, all too often. Unfortunately, before I discover it so... the battery often sits dead for several days or more; sulfate'ing away, all the while; i.e., getting deader & deader each day, before I actually discover that it IS dead. If dead (sulfate'd) for too long (a week or two?)... the bat is unrecoverable; and then requires replacement. I have multiple, high quality bat chrgrs, but, if the bat's been sulfate'ing, it can take up to several hours, or more, to get it to accept enough charge to (barely) start the car. I have no garage, so the car lives on the street, out front; and it is not practical to use a Battery Tender/trickle charger on it (pwr cord/public sidewalk/safety issues). When I think the bat's getting marginal, I start the car, and run it for 15 minutes, to top off the bat. Background, complete. In reading the Amazon reviews (and some from other sites) I noticed a couple of reviewers lambasting the Gooloo unit(s) for having a small, actual AH (Amp Hour) rating. I had already been wondering how SUCH a small unit... could start a car; much less, the over 60 times per charge claimed for this unit (and, that, at ONLY 50% or greater retained charge [not supposed to use it to jump-start, at all, below 50% charge]). In the specs, this unit is rated at ~ 98 WH (Watt Hours). No actual AH (Amp Hour) Rating is provided. I've been in electronics all my career, so have the wherewithal to apply the appropriate math to the issue. 98 WH IS a tad under 8 AH; just as the negative reviewer(s) were/are claiming. It appears, however, that they were wanting to use the units to run some sort of meteorological/ecological instrumentation setups (?); and, sure enough, only 8 AH is hardly going to get that sort of job done! So... how does this all compute? A little more background is needed, here. Mfgr's commonly use a procedure called 'binning'; essentially, dividing the production line output into, essentially, Good, Better, Best ratings. Three-level binnings are common, though you can obviously go further; until reaching the level of full rejection/unacceptable performance/failure. I literally have dozens of Makita brand, battery operated tools; and have something like 37 batteries for same, in two sizes (AH Ratings). Most are fairly old, the oldest being in excess of 15 yrs. I used to pull all the bats every six or eight months, and run them all through my chargers. However, I found, over the years, that they (unless the bat/unit had been recently/heavily drained) typically achieved full charge in under five minutes; occasionally, as long as 30 mins. Commonly, though, most of my Makita bats reach Full in under 30 seconds!! (basically, the ones that have been sitting in unused tools - as long as a year - or more). Anymore, I run the Kita bats through the chargers only on an annual (or, longer) basis. And... with the same consistently impressive results! They REALLY hold a charge well!! This is a good example of First Binning lithium-ion cell selection (a 'battery', by definition, being comprised of multiple 'cells'); i.e., the batteries only contain the highest quality cells. At the other end of the spectrum, are the bats for my Ryobi brand tools (Home Depot). The Ryobi tools are incredibly cheap, and a 'relatively' good value; even if you just use them up to destruction, and then simply buy new replacements; as I've read some construction workers claim to regularly do. Unfortunately, the Ryobi batteries are the complete opposite in value. I quit buying them after eight batteries (I've had to toss out two, and have two more that are minimally functional/very difficult to take on a charge). Unlike the Makita bats, the Ryobi bats are only avlble from Home Depot (no where else - like at Amazon, for instance). Further, they charge $80 per bat, and are never discounted. Of my six remaining Ryobi bats, ALL fail to hold a charge for more than a month or so; and several, won't even hold a charge for a week or more. Further, unlike the Makita bats, they also don't seem to perform anywhere near their AH Ratings (also, compared to my Milwaukee tool bats). Though, I'm simply too lazy to have actually run AH Rating analysis on them (fixed resistor load, over measured time, to a set level of discharge). This is an obvious example of Third Binning (or, worse) cell selection. I might also note that this is old history. I recently noticed that Ryobi has newer lines of their bats, that appear to (possibly) be of better quality/value. But, having been soooo burned, in the past... I've not invested/investigated, further. Nor, plan to. When Milwaukee started up in competition to Makita's battery line(s) of tools, quite some years, back... I encountered multiple quality issues with their batteries, too. I had to toss several, as completely unusable/failed. That's when I discovered that procuring individual replacement cells, with which to change out the dead cells/repair the battery, was actually more expensive than simply buying a new battery!! I'd guess, when they were starting out, that Milwaukee was using Second or Third Binning cells. But, over time... as I replaced the trashed bats with newer ones, I think they had realized their error, and had moved up to using First Binning cells; as, from that point onward, and, to this day, I've had results with their bats, similar to the excellent experience(s) I've always had with my Makita bats. So... a large, 8-cylinder ICE-type engine's starter, as I recall, typically draws several hundred amps off the battery, during starting. Just for grins, and ease at math being done in my head, I use(d) 333 amps as an average draw. Obviously, with smaller engines/starters, the draw will be considerably less (or, somewhat more, in the case of a BIG truck's diesel engine, say). My car's engine is a 6 cylinder; so, maybe around 200 Amps, max? Assuming an engine is in good tune/shape, a typical start takes 3 seconds, or less. Say, five or six, if the engine is 'less than optimal', for what ever (hopefully, temporary) reason. Soo... 333 Amps, for three seconds, computes to roughly 0.1 AH draw (load). Thus, at the above loading level, dividing 8 AH by that 0.1... will yield '80 starts'. But, limiting to 50% Gooloo battery charge, and, just for grins, assuming linear performance from said battery, say... 40 starts. Then... figure that, most often, many starts take LESS than one to two actual seconds (time it off in your mind, then compare to your usual engine starting time duration experience). So... boost that '40 starts'... up to 60 starts. Which, in actuality, isn't at all that unreasonable a claim. That all assumes the Gooloo battery IS capable of a very high, short-term current (Ampere) output. How to assure that? First off, use ONLY the highest binning cells for the batteries. Likely, they even use 'special' cells; designed and selected for extra-high amperage output. Then, instead of using only one or two spot-welded straps to interconnect each cell to the next one, let's assume double, or even triple the number of straps. And/or, to further augment high current capability, assume usage of much heavier (lower current resistance) straps. Then... lets maybe assume using the types of cell construction developed for the electric car industry (obviously, high-quality, high-current-drain-capability cells needed, there!). Or, equivalent. And, thennnn... lets include enough cells in the battery (in series, that is - the voltages adding serially) to have a higher output voltage (often analogized/compared/equivalent to water pressure, in a hose); so as to more easily drive/supply higher current (volume - i.e., G.'s per minute of water) from the battery. I measured the output of the Gooloo unit I have; and it measures over 16 Volts (unloaded). At 3.7 Volts, nominal, per lithium cell (up to 4.2 Volts, fully charged), often mfgr's will claim 12 Volts, off off 3 cells in series. Better to go with four cells - 14.8 Volts, nominal. So, at 16+ Volts measured... maybe Gooloo uses five cells in series; or, perhaps, one of the alternate lithium chemistries (such as lithium-phosphate) - resulting in slightly different voltages per cell, and a slightly different total, for the overall composite battery. Add all this together... and I can understand how such a small battery (8 AH) CAN easily start a car. And, often... say, 50 or 60 actual jump-starts per charge cycle. Now... how did all this work out in my ACTUAL experience, today? To start, my battery was 'dead as a door nail' - i.e., deader than dead. Nada. Wouldn't even allow unlocking the door(s) (or, gas cap cover/opening the trunk) from the remote fob. Arrgghh! So... a prime case with which to test the Gooloo. I didn't want to pull the rear seat, to gain direct access to the battery, so popped the hood, and connected the way I usually use one of my battery chargers to try to recover/charge the dead battery - connecting the Gooloo's Black lead/clamp to a bolt on the engine's alternator mounting assy, and flipping up the plastic 'safety cover' leading into the primary fuse box's incoming 'Plus' terminal (my car has a secondary fuse box, near the battery, under the rear seat. Go figure.), to connect the Gooloo's Red lead to. Since the bat was soooo dead... and as outlined in the Gooloo's Instructions... after obtaining the Green light on the jumper cable module as blinking... I pressed the little nearby 'Boost Button'... and got a solid Green. As soon as I had connected the Gooloo, and prior to pressing the little button, all my running lights and such, had lit up merrily bright. 'Encouraging!', I had thought. But, when I got in the car and hit the starter... all I got was a short 'blip' - no starter turn-over - and... all the lights went out. Grumble, grumble!! But.... I certainly wasn't ready to give up. Yet. I got back under the hood, and checked my connections. When I jiggled/ck'd the Black lead... I got sparks! Indicative of an inadequately secured connection. I made sure it was WELL clamped in place, this time, jimmying it about as bit, so the teeth of the clamp could pierce through any oxidation on the bolt-head I'd chosen. And... all the lights came back on - brightly! THIS time... when I hit the starter... the engine spun enthusiastically... and - 'Vroom'! - started right up! Happy camper, I!! :-) :-) So... I am VERY confident & happy, now, in/with my Gooloo unit. And, by my above suppositions and calculations... do not doubt the claimed '60 jump-starts' being advertised/claimed for this unit. I'm impressed with the Gooloo in ALL considerations (as so well detailed/outlined by the other reviewers). HIGHLY Recommended!! Addendum: It's about ten days later from the above, now. Once again... grumble, grumble... my car's bat is all sorts of dead. Only this time... the Gooloo couldn't start it - at all. I had noticed that Amazon had posted my Review as the 'Most Positive' review. I hope it stays that way, as I am still feeling very positive about the Gooloo unit; but... now having encountered some real world limitations to it's 'practical' usage - thought that they were worth being noted, here. I had also noticed that the 'Least Positive' review had complained that the Gooloo was unable to start his vehicle, when he had a very dead battery. Considering my success with doing just that (in the upper/first part of this review), I was a bit... puzzled/surprised. Well... no more. Apparently, earlier, I DID have a very dead battery; but... no where NEAR as truly double-dead-dead as with this 2nd attempted use of the Gooloo unit. As before, I had connected the Gooloo, engaged the 'Boost Button', and got (external) running lights; but lost all, when I (unsuccessfully) tried to start the vehicle. Just got nothing; no starter turnover, and 'lights out'. The Gooloo went from Boost Mode, back to a blinking green light on the jumper module. Tried it several times; same, each. Arrgghh! However... I did recall that the instructions advised letting the Gooloo be attached for a few minutes PRIOR to jump-starting; which I had been knowledgeably/purposely been avoiding doing, as I had been more interested in subjecting the Gooloo to worst case, 'street' conditions/usage. Well... things just got even worse for it, this time. Sooo... I decided to let the unit hang onto the car's bat, and transfer some charge into it; in hopes that that would enable the Gooloo to, a little bit later, jump start it. Fortunately, all this is/was going on at my residence, not 'out in the wild'; although that was exactly why I was trying this particular methodology out - like this, here & now. In watching the unit, I noticed the green light cycling - 6 seconds On, one sec Off, then, repeat; consistently. After having gotten bored watching that, I moved over into the shade of the building; from which vantage (out of the bright [hot!] sun at the front of the car), I was able to observe the rear running lights. Which were bright for four secs, dimming to being out completely, over the next 2 secs, remaining so for the 1 sec the jump cable module's SoC ('Solution-on-a-Chip' - the industry's nomenclature for a custom-designed, single-purpose IC chip) was using to Reset itself, each cycle, and then repeat - over & over. So I felt confident that the Gooloo WAS transferring charge into the vehicle's battery. (Which did, indeed, later prove to have been the case). After all was over, I plugged the Gooloo unit into a charger, via USB-C. Before, the unit was showing 2 solid bars (when I disconnected it); now, while initializing charging, it had 1 solid bar, and was blinking the second one (later, progressively, the 3rd and 4th ones) - thus, my conclusion that I HAD xfer'd OVER half the Gooloo's charge into my car's battery. BTW, despite being connected to a 50W charger/wall-wart, that I often use on my Samsung S23 Ultra cell phone, the Gooloo took 5 hours to reach Full charge; thus leading me to the conclusion that the unit's firmware does not honor/recognize Hi-Speed USB charger protocols (perhaps introduced AFTER the Gooloo's design phase had been locked in place?). But... after 15 minutes of charge xfer time had passed... the Gooloo still couldn't start the car. When I disconnected it, I noticed that the Gooloo bat's power indicator showed 2 bars (see above); indicating it HAD xfr'd some energy into the car's bat. A bit over half of the Gooloo's 8 AH capacity, as DID actually prove out. And... the instructions DO state NOT to try jump starting below 50% charge (which this unit WAS at, at that point). So... maybe... had I only xfer'd charge for, say... 5 minutes?... MAYBE... the Gooloo (being at over 50% charge, at this 'conjectural' point in time) WOULD have successfully jump-started my car. I'd like to think so; and, if similar circumstances present again, in future, will test out such. Back to today... I then set out my safety cones, ran out an extension cord, and hooked up my (larger) car bat chrgr. Which, like so many things, today, is waaaay over-software-engineered; meaning that all the supposed advantages to doing so, during the design phase... often result in annoying, real-world limitations, in day-to-day usage scenarios. Which, in this case... the charger wanting to see at least a FEW volts on the battery... often leading to hassles getting the durned thing to actually charge the battery at all - when encountering a very dead one! Fortunately, however... in THIS circumstance... it read out 4 Volts present in/on the car's battery; thus verifying the Gooloo's energy xfer. I let the AC charger do it's thing for about an hour... returned to find that car's bat at ~ 11 Volts, and maybe 35% charge, and, then, managed to successfully start there car. WHEW!! So, for 'normal' dead battery issues, and with an otherwise viable, healthy battery... I feel the Gooloo unit is STILL to be Highly Recommended. However... when encountering VERY dead/unhealthy-unhappy/compromised batteries (like mine was/is)... it would be wise to be aware of the above limitations. Best of luck to you all.

I had battery booster that suddenly quit working because it couldn't be recharged. That item now costs $300 so I looked into others and found that this GOOLOO booster would probably suit my needs for less than a third of the cost. When I received the product, it was so small I was thinking that I had fallen for some scam advertising or a cheap product that wouldn't work more than once or twice. Boy, was I surprised to find out I was entirely wrong. Unfortunately I've had to use it several times already since I purchased it. Nearly every time it fired up the car better than the fairly new battery in the car does when it is fully charged. I've used it several times in a row without a recharge and each time it provides all the power needed. That's proof that it doesn't need to be recharged after each use. The only time it failed to get me started was when my battery had been discharged to 0% - totally dead. But that's to be expected and the instruction are clear that it is not intended to do this and will not start a car with a fully discharged battery. The booster comes in a very nice and attractive carrying case which would probably fit in most cars' glove box. What I don't like about the unit is that the cables are separate from the booster itself and must be plugged into the unit before each use. At night this can be very difficult to find the receptacle and align the plug. The instructions prescribe a certain sequence for connection too which I do not recall at this time. You must either plug the jumper wires into the unit first or connect them to the car first before turning the unit on. I can never remember the sequence and it is not printed on the unit itself as a reminder. I haven't noticed any difference in the way it works between the two methods so lately I have been plugging the cables in first and then attaching the positive cable to the battery followed by the negative. When I do this the unit powers on by itself and is ready to go. Another complaint is that it is difficult to repack the unit, battery cables and accessory into the nice little carrying case so that you can zip it up closed. There are two or three compartments in the bag for stowing the items. It would be much easier if there were only two (one for the unit and cables; the other for accessories) or none. Recharging is done via USB so you can readily plug it into your car's USB port or use an adapter to use the car's power outlet. Then as you drive along it will recharge the unit. That's convenient because then you will always have the unit fully charged and you won't be forgetting at home or office because you left it there to recharge. So, there are some things that could be better but for a savings of more than $200 it still does what it is meant to do - jump start your car - as well as any fancy high-priced unit on the market. In fact, the battery went dead while my car was in the garage for an inspection sticker. The owner used my unit to start my car because his was not fully charge and was too inconvenient to get to. I recommend this product base on personal use and great results.

We REALLY like our Gooloo Jump Starters. We have one in every car. We have used them multiple times to help people in parking lots who might need a jump. Our daughter is even good at helping out other kids at the high school if they need a jump. She is known as the "Jumper" (she is also a high jumper). These always work. They are just the right size for storage in a vehicle. Not real sure if I prefer the soft case or the hard. I like the look and the protection provided by the hard case, but it does take up more space. I like the fact that you can't mess up attaching them (nice and safe). Ease of mind for me if my children have to use one. Solid build quality. The only issue I have is that looking back I would not mess with the lower amp <3000A units. Not necessarily anything wrong with those, but I prefer the 3000A or higher. With all of the different vehicles we have used them on, the 3000A seems to work great. We initially purchased the different sizes based on the vehicles they were going to be in. And, some of the smaller amp models were a great price. The 2000A works great for our 2006 Honda Cr-V. I tried it on few larger vehicles (larger batteries) and it struggled a little with some of them. Note, the 2000A was NOT recommended for the larger size vehicles. BUT, if getting one, you may want to just step up to a larger size even if it is for a smaller car, because you never know what other size of vehicle you might need to use it on. They were changing the look of the different styles/models for awhile. I have no idea if it was just cosmetic or if there were interior changes. The previous models appeared to be a really good deal for awhile. The problem was, that at that time, there were several models listed on Amazon. At times it was a little difficult to sort the different models out. I ended up going to the Gooloo website and made comparisons there. Then I ordered accordingly. The BIG displays on some models are nice, but they do make those models more expensive. And finally, I unfortunately cannot report on the longevity of the individual units. Sorry. We have had all of them for over a year and they all still work. Most have been almost fully discharged at least once. I check them on a regular basis and have not noticed any natural drain of the units (Kansas hot and cold temperatures).

Saw this brand in a Project Farm video take top honors. I had never heard of it before and honestly, it sounded like some cheap, mass produced, white label offbrand. But, Todd's recommendations have never let me down before, so I purchased the highest capacity Gooloo to cover all passenger vehicles and gave my other jump starter away. A couple of weeks after purchase, I encountered my first situation to use it. A Cadillac SUV had died at a gas pump and needed to be pushed out of the way. I offered to help and attempted to hook up the Gooloo, but couldn't. The battery was buried way in the back (thanks GM engineers), and the plastic coverings on the clamps made them too bulky to angle in correctly to the positive terminal, so the Gooloo couldn't make a full connection. Useless. Someone else came along with a tool truck brand jump station, connected it, but the SUV wouldn't hold a charge. The driver ended up buying a new battery and had a family member swap it in the parking lot. I have no idea if the Gooloo would have worked, but I didn't even get the chance to try. I was starting to regret my purchase a little bit, because my old jump starter had thinner clamps and would have at least attached. What good is an emergency tool if you can't use it? Well, yesterday, three months after purchase, the Gooloo got redemption. I get flagged down leaving the store: an elderly, disabled lady in the parking lot had a Hyundai sedan that wouldn't start. Four year old store brand battery, rapid clicking when turning the key. She didn't even know how to open the hood. She had attempted to call her nephew for help, but he was over an hour away. It was getting late and the store was closing, so she had begun to panic about being stranded alone in the dark. I hooked up the Gooloo (successfully this time), and gave it a shot. I was worried, because every other jump box I had used had never worked on a battery this far gone. First attempt, still clicking. Second attempt, I hit the Boost button. The car fired right up. Worked like a charm. I told the lady to go straight home but to drive around her neighborhood for 20 minutes to try to get the alternator to charge her battery. She was able to drive away, safe and sound. Despite my first experience being a failure, I would consider my purchase 100% worth it for being able to help even just one person, especially someone in a vulnerable group. That battery was heavily discharged and the Gooloo was very impressive. Most vehicle batteries will be readily accessible and not like that awful Cadillac design, so I would still take the odds with this brand that it would be able to help 99% of the time. I would highly recommend.

i have two of these units. the oldest one has performed flawlessly and holds a charge for several months, it has been used to start many vehicles and pieces of farm equipment as well. the second unit started out working just fine but developed a problem about 1 year after purchase, it would no longer hold a charge and then loose its charge after about a week of being recharged. I reported the problem to the manufacturer and followed their instructions, made a video and received a replacement unit a couple of days later. hope this unit works like my original one - the customer service was fast, responsive and first rate.

I've had this unit for 2 years and 3 months. In that time, it's been in my truck under the rear seat continuously through summer heat and winter cold in Wisconsin. I haven't had a chance to use it to start a vehicle until today. When I first got it I tested it by starting my lawn tractor while the battery was disconnected, and I tested all the ports on it by charging my phone and powering a satellite radio for a few minutes. I've topped off the charge maybe twice in all the time I've had it, and again this morning when I found out I would be using it today. My stepdaughter's battery in her 2006 Chevy Equinox had been dead for a few days since our recent two-week cold snap when it got down to -23F one night and well below zero almost every night (it's Feb. 2, 2026 today and +20F). Nothing happened when turning the key, so the battery was fully dead. I hooked this unit's jumper cables up to her car and the green indicator light started flashing, which according to the instructions means the vehicle's battery is extra dead. I pushed the BOOST button according to the instructions, the green light stopped flashing and stayed on steady, and her horn started honking, car alarm style. I think the sudden shot of power from the Gooloo makes the horn honk because I read that it also happened to another reviewer. I told her to try and start it, and when she turned the key the engine was running instantly. No moaning, groaning, or cranking, it spun over fast and started right up. You can't get better results than that when you're jump starting a vehicle. Afterward, back at home, I checked the charge level and it still had three out of four bars lit up after having used the boost feature. I plugged it in to charge, and it took 35 minutes to top it off using my phone charger. Now, it's back in its case and back under the seat of my truck, ready for next time. I'm very impressed with this thing, and very happy I bought it. I imagine it will some day wear out just from reaching the end of its storage lifespan as all batteries eventually will, but that should still be several years away. I was so impressed with it today that I wanted to go drive around and look for other dead cars to jump. It really is a marvel of modern technology that such a small unit can store and release enough power to zap an engine instantly back to life after being frozen for days.

Following directions, I charged the Gooloo jump starter until all the blue status lights went out. This took about 3 hours. Today, I used it to jump start my 2005 Chevy Avalanche. It had been sitting in the garage for 2 months and its relatively new battery was DEAD! I mean dead! No lights, no nothing. Not a single indication that there was a battery at all. My battery has side connectors so I wasn’t too hopeful. After connecting, the green light on the Gooloo was flashing so I pressed the BOOST button and gave it a whirl. Amazingly, the starter engaged like the battery was fully charged! And it started! WOW! So 5 stars! Some caveats: The instructions are sparse and poorly written. The diagrams were not accurate. The instructions told me to press the BOOST button. But where? The diagram showed it to be on the jump starter battery.But no BOOST button. I finally found it on the clamp cable connector that attaches to the jump starter. And also the green light. Still, I’m giving this thing 5 stars.

Always wanted a jump pack. I needed it for a Dodge Challenger 5.7L engine. The battery was mostly dead. The GP4000 spun the starter faster than I had every heard it spin. Wasn't sure it was going to work but it exceeded my expectations.Only paid $87 for it. Other packs were over $100 and even over $200. This pack features over/under current protection, terminals reversed by mistake, spark proof, etc. It's USB charged. Don't use a low wattage typical charger it will take forever to charger. I bought a 65 watt charger. It charges my phone much faster, BTW

👍👍👍