I presented a tough scenario for the Super cap 2 to prove itself on a low battery located under the rear seat of a gm car.And it did not work as advertised, utilizing the Super cap 2 alone failed in the above scenario on the first attempt. I then connected car #1 to car #2 using jumper cables and was able to get lights and alarms to power up but still not enough juice to start it. I then added in the Super cap 2 to a location under the hood for normal jump assist's and then the Super cap 2 was able to provide just enough additional energy to turn the engine over so it would start.The Pros The tech behind it makes sense instead of using lithium batteries it uses Capacitors for storing a Pre-charge of energy and it should work on something that wasn't so depleted maybe where you have dim lights and the dash lights up but doesn't have enough juice to turn over the engine.Unlike a Lithium battery this unit can be 100% pre charged in less than 10 mins. While it wouldn't start the car alone it did tell me the system voltage and that the battery was low, when the car was running it does display the charging systems voltage output.I did have to also use the accessories to pre charge it in car #2 it comes with a nice carrying case a USB cable as well as a cigarette lighter socket plug mechanism for pre charging it.The Red and Black cable attachment is removable and is designed in such a way that you cant accidently install it backwards.The consI felt it doesn't work well with GM side mounted battery terminals, due to the batteries design the clamps kept wanting to come loose, maybe some sort of offset shoes should be included for insertion between the actual battery terminal and the cable then the clamp's could connect to the shoe instead of the small cable attachment bolt.The instruction manual is really vague on what to troubleshoot it did show a chart on the various readouts but then nothing to suggest what each one meant and how to correct them.Update: I had a no crank but the lights came on and this device was abler to operate properly and was able to provide enough current to start the car.

Slower to charge on usb than advertised

Good solid build, draws it's power from the flat battery. So if your battery goes flat and no one else is around it could be a live saver.

I'll start this review by saying I own both this Autowit jump starter as well as their previous model. As such, I can compare them fairly well. You may have seen this product on a popular YouTuber's channel and while it doesn't come out on top, I'll explain why this technology is right for me.I live in the subarctic where winter's super cold temperatures are the norm rather than the exception. The problem with battery based jump starters in cold climates is the battery won't hold a charge while stored in your vehicle for weeks/months at negative temps. These capacitor based systems are essentially immune to this problem, since you charge them when you go to use them and also there is no battery chemistry involved.Conceptually, this unit will take remaining energy from your insufficiently charged battery - and release it all at once, allowing you to jump start your rig. It suffers with really weak batteries, but really, it just takes longer to charge. While it's true that it won't charge from a truly "dead" battery, this is really a better application for a battery charger anyway. That said, you could use the DC accessories to plug this into an alternate power source (another battery, USB or cig lighter adapter) and start a truly dead battery.When I need a jump starter, it's because it's been -40F for a week+ and I haven't started my vehicle. In fact, I've put my old Autowit through exactly that exercise more than once, down to -46F. I gladly bought this updated model for my second vehicle as it's been such a helpful and versatile tool to get through the harsh winters. I've tried this newer one out a couple of times and expect it'll do every bit of what the old model will do. For me, a tool like this needs to be operational at all times (not just fair weather) and this fits the bill nicely.There are some differences and "upgrades" found in this unit, compared to the old version. First, the cover for the plugs is a nice rubber insert, which is infinitely better at handling cold temperatures than the (now rock hard) plastic insert they used previously. The display is nice, it gives you battery voltage and general indicators of status. The buttons are a little more clear in this unit and there is no longer an "on" button, it engages when clamped to your battery. Most importantly, the unit gives you audible clues (beeping) that you can use to know precisely when to start your vehicle. That feature is completely absent on the old version, meaning it was a bit of a guessing game of when to try starting your rig. I also super appreciated the storage case that comes with.As for the bad? There's very little in my opinion, most of my critiques were corrected in this updated model. If I had to pick one thing, it's that the beeping isn't quite loud enough. It's really hard to hear (even in deafening silence) since the hood is often up and in the way of when you need that audible cue.As for the popular YouTuber that rates these - his "cold test" really needs to be multiple weeks at -20F or lower, like it might see in the real world. Overnight in freezing temperatures is nothing, not even enough to take out my battery to begin with. This is one of the only units that is suitable for this scenario. Even if you're not facing these odds, this is still the "survivalist" version of a jump starter - one you can take anywhere and jump almost anything. It's a trusty bit of kit in my book and that's why I now have two of them!