autowit SuperCap 2 Lite 12V Batteryless Jump Starter (Up to 5.0L Gas, 3.5L Diesel Engine) 700A Peak, Built-in SuperCap, No Need of Regular Charge, 10 Years Lifespan, Extremely Weather Operating

I love this device. I had to test it out by placing a very dead battery in my car last weekend to see how well it performed. It is a very handy unit. There are some important things I did find out though.1) You need to make sure before jumping that you have indeed turned off as many power draining devices as possible. Check AC/heater fan, radio, close door so dome lights turn off, turn off auto head lights.2) The instruction manual lists three methods to charge the device if your battery is too low to charge it (if you have at least 5 volts you should still be able to charge it but it will take some time), the methods are not in order of quickest way to charge the device. The order of quickest way to charge would be 1- directly off someones fully charged car battery, 2- Off of the cigarette lighter from a vehicle with a well charged battery, 3- through a 12 volt power supply (the higher the amp supply the better) connected through the 12v input port. 4- through a 5 volt power supply connected through the 5 volt input port and with a current above or as close as you can get to 2 amps ( I have a 1.85 amp phone charger that worked). If the 5 volt power supply is below 1 amp I don't think it will even charge the device. At 2 amps it may take it up to 20 minutes.Note : a 12 volt trickle charger such as the harbor freight unit that has only 850mA can be clamped to the cigarette lighter ends and will charge this faster than a 5 volt phone charger that is below 1 amp.3) You need to make very sure you have a good connection to the battery terminals. It would be a good idea to include a small wire brush in the box with this, or in the tools with your car. Get all the corrosion and acid scraped off the site on the terminals you are connecting the jumper device to. This is very important and if the device doesn't work the first time, top off the charge, re-seat the connections on the battery terminal and try again.4) This device has enough power to start the car even if the battery is not present. I completely disconnected my battery and started the car with the device to prove this to myself. It worked fine, but I did have to make sure all the above was true. I did connect it and have it click with starting the first time a time or two and had to investigate. Don't assume that if your car just clicks it is because the device is under powered, trace things down and check it out.5) You need to make sure the device is in the right mode to deliver the starting charge. If the cars battery has enough power it will flash red as its charging the device, once it gets enough voltage that it should be able to start the car it will flash green, once it fully charges the unit it will automatically enter start mode. Press start before entering the car so that it will deliver the required starting current to the car. If you have charged the device elsewhere, after connecting the device to the disable vehicle, you press the power on, then after the voltage light flashes green, you press and hold the overide/power button for a couple seconds to deliver the starting current to the car. You may not be getting the unit into the correct start mode if your car doesn't start. You can generally tell it is delivering the necessary current by your cars dome lights, door alarm, instrument panels, etc. You should have some indicator that the voltage/current is being delivered to your vehicle.Other reviews said this will not start with a dead-dead battery, this is not true. It will. Also, it will start with the battery completely out. I tested this myself and found it to be the case (it started a V6 ford explorer). Other reviews also assumed that charging on the 12-v cigarette lighter would take hours to charge (just like their under-powered 120 - v to 5-v low milli-amperage phone power adapter did). Charging off a 12-volt car cigarette lighter takes only a few minutes if the cars battery has a good charge. I also read a review complaining about their battery location being in the wheel well/bumper. This device can still connect to the same location as the manufacturer has set up for jump starting the vehicle and work. If the device doesn't start a car with batteries in remote locations, then the above items still apply. You need to check connections/corrosion discharging devices, etc. It should still be able to start the car with the battery in the remote spot.I admit that needing to have tools to possibly disconnect a battery terminal if the battery is deeply discharged is an inconvenience. I also admit that having to rely on another person with a charged battery isn't much different than needing them when all you have is jumper cables. So the inconvenience of a deeply discharged battery is a pain. But I kind of doubt many in an emergency situation will find that they have discharged their battery below 5 volts. I believe it takes about twenty minutes to charge the unit up if you have at least 5 volts left on your battery. At least in a low voltage battery state you have hope that the super capacitor will charge-up in about 20 minutes and get you out of there.If you are in a place where there is no-one to jump you, or you're battery jump starter hasn't been charged for months because you just didn't think about it, then this thing is your best hope.Love that you don't have to keep a charged jumper in your car: Battery powered lithium battery units are killed by being stored in HOT (read your cars) environments. Many battery pack-jump starters have to be well maintained. There is no maintenance on this.I ironically had to use this today. I think my battery was well charged and it was a connection between my terminals and the battery. But the convenience of this was great for getting me back on the road. No, it did not work the first time. I had to wiggle connections and try starting a couple times before the charging unit started showing voltage and things charged right. Once I checked connections, it worked great and I was on the road.The only reason I am not giving this 5 stars is because I recently bought a different brand unit for my wifes' car and prefer the all in one simplicity of it to this Autowit unit. The Autowit has a higher starting current rating, so - for the price - it is a better device than my cheaper unit. So if this was an all in one unit and a little easier to connect, I would have given it 5 stars.The ultimate in prep would be to have this device and a lithium battery pack jump starter/phone battery pack with you. Then you could use your lithium/phone battery pack to charge the supercapacitor if your car battery was too dead and the lithium/phone unit was too dead to start your car.Remember, this device starts your car even with a "Dead-Dead" battery (or completely absent battery). So check your connections!Added later After further testing:I did some more testing with a different vehicle with the battery in the wheel well. I started the car with the battery completely missing from the wheel well first. It started fine. I then put in a weak battery and tried it out.Initially the jump starter would charge just fine and the car would start no problems.As the battery became more discharged, it eventually would indicate start mode on the starting device, but when ignition was turned to start nothing happened. I surmised the electronics weren't sensing the ignition key going all the way on and wasn't delivering the start voltage yet. Tapping the horn just prior to turning the ignition to start took care of this problem and it started fine.After discharging more, eventually tapping the horn did nothing. I then found I could do the following: Charge the device remotely, Connect the positive clamp of the starting device to the positive jump start terminal, Power on the starting device until the green voltage light comes on, press and hold the off/on override button for about three seconds until the override light starts to flash, while the override light is still flashing-connect to negative clamp to the negative jump terminal, immediately climb in the vehicle and turn ignition to start.Generally the car will start without having to disconnect the battery cables if the above is done.I am raising my rating to five stars because I am very impressed with this unit and its ability to start a vehicle. If I had to choose only one jump device to be with me and it was between this device or a traditional battery device, I would prefer this device. In most cased this device will still charge off the battery even if the battery is in a very low discharged state. It may take it an hour to charge if the battery is that seriously discharged, but it could do it I think. If a traditional battery jumper is in a discharged state, there is no way it's going to get the car started, whereas this unit may as long as there is enough charge to get the unit to build up a starting charge.Things you should know:Solid Red or Yellow - unit is on, doesn't have enough voltage to start vehicle, unit is not chargingPush button goes to Flashing Red or Yellow - unit is charging - When the unit reaches 14.5 volts the voltage indicator will change from red (or yellow) to green.Solid green on voltage Solid green on override -unit is in start mode- unit does not deliver starting voltage until it senses starting attempt. Usually this is just triggered by turning ignition to start. You may be able to get this to "trigger" by beeping the horn just before turning ignition all the way on.Can't get solid green indicators from both lights? Charge elsewhere first, connect + first, turn on, push and hold on button again for three seconds until override light starts to flash, connect - prior to green light turning solid, enter and start vehicle just after override light turns solid green and car will start.Love, Love this device!

I was able to successfully use it to start my car, in a real life situation (see near end of this review for details).Initially, I did some experiments with it. I charged it via usb port and then used a multimeter to measure the voltage on the red and black clamps.One thing I noticed was that the device did not emit any voltage/current on the red and black clamps as it was charging up. Then, after the Voltage LED light changed to a steady green, the only way I could get it to emit voltage/current on the red and black clamps was to press and hold the ON/OFF button for about 4 seconds, at which point the lights start blinking and the Voltage/current is emitted on the red and black clamps. My experiments suggest that both lights have to be steadily on, for an actual voltage/current to be emitted on the red and black clamps.One caveat: when I disconnected the USB power cable from my device, the device seemed to shut itself off automatically (both of the two LEDs lights were off).If you try to press the ON/OFF button for 4 seconds while the device has both LEDs off, it won't work -- you have to turn on the device first. To turn on the device, briefly press it's ON/OFF button and then wait a second or two for the device to come on.Once the device is on, you can then press and hold it's ON/OFF button for about 4 seconds, to get it to emit voltage/current on the red and black clamps.I mention this because I found the directions to be a bit confusing and I wasn't getting the results I had expected.But for the most common use case, which is where you use a car's weak battery to jump start itself, it looks pretty simple and Autowit has a 4 step picture tutorial on their site that walks through this common case.I would strongly suggest that, if you get it, you spend some time experimenting with it, hooking up a multimeter to track the voltage that is being emitted on the red and black charge clamps. The multimeter helped me to understand what the device was actually doing at certain points in the process.Part of the reason why I got this was that I've had people ask me for a jump start in the past. And lately I've been a reticent to do so, since if they don't know what they're doing they could damage the electronics in my car.Now, with this device, if someone asks me for a jump start, I can simply whip out this device and use it to help them jump start their own car without risking potentially expensive damage to my own car..--Just an update. A few weeks ago, I was at a gas station and my car wouldn't start. I used my Autowit to successfully jump start my car! It actually took two tries, but it did work! Autowit definitely saved me from having to wait an hour or two for AAA to show up.. Very cool!---BTW, here's the crib sheet that I created for myself, that I keep with my Autowit Charger, for easy reference:Using the car’s own weak battery to jump start itself:1. Ensure the charger is in an OFF state (two indicators are off).2. Connect the red and black clamps with the battery positive and negative poles, respectively.3. Press the ON/OFF button. The starter will start to recharge itself.4. When the voltage indicator stops blinking and becomes a steady green, and the ‘START MODE’ indicator turns into a steady green, meaning that you now see two steady green lights, the red and black charging cables are now ARMED and delivering current.5. You can now start your engine.6. After the car has been successfully started, press the ON/OFF button to turn off the charger and then disconnect the clamps from the battery.