Schumacher DSR108 DSR ProSeries Batteryless Jump Starter - 12V, 450A for Gas and Diesel Engines

These are the best jumper you can get IMO. At least, that is to say I believe that ultra capacitor jumpers are the best. This one has no problems, and even supports a glow mode for diesel glow plugs. Not all capacitor packs do.These work differently than a battery. Capacitors can dump all of their energy very quickly, as well as charge quickly. However they do not hold it when sitting, and they do not hold very much total energy. This means it will provide extremely high energy cranking (more so than your normal starter battery!) but only for a few seconds before needing to scavenge more power.If your car cranks a while before starting, this will not be the jumper for you. If you car always starts right away, this jumper will never fail to start your car.Lithium battery jumpers hold onto their charge and have a lot more total energy, but will likely be dead when you need them if you just leave them in the car. They also wear out extremely fast and are a fire hazard under the extreme conditions of starting a car. Oh, and they flat out don't work when frozen. When you most likely need them. These capacitor jumpers on the other hand are nearly indestructible.They work perfectly even in deadly extreme conditions, and they work without fail.This device works by drawing energy from your battery and boosting the voltage to fill the capacitor bank. This takes about 2 minutes, depending on how much voltage is available in the dead battery. Upon filling completely up, it monitors for a sudden reduction in voltage and assumes you turned the key to start the car. It then dumps all of that full 13+ volts back into the car battery at high amperage, but only for a few seconds. Even on a big V8, this never failed on any vehicle I tested it on.Some newer cars, particularly Fords will not even attempt to do anything when you turn the key at low voltage. No clicking, nothing at all. In these cases you have to press the button on the capacitor pack to start a count down beeper. Quickly get into the vehicle and be ready to start it. As soon as it gives the go, crank the engine. It should start right up.In the event of a failed attempt, you need to wait for the capacitors to charge back up before trying again.If your battery is absolutely zero volt dead, think of this jumper like a cordless jumper cable! Just clip it onto any donor battery or vehicle and wait until it's full. Then bring it over to the dead car and start as above. Even if you don't have that option available, you can even charge this pack (SLOWLY) via USB C or fairly quickly with the included 12v lighter socket adapter. In general, if your dome light can even slightly glow orange, this will charge up and start your vehicle without any outside energy source.I've used one of my fleet of these over 30 times, it works as new still. It can start my turbo diesel jeep, which really takes a LOT of amps to start. My only complaint is that the admittedly nice silicone coated wire leads are a bit short. I would also sort of prefer if this used an EC5 or other connector so that the leads could be replaced or removed for storage. The weakest component of this will be the wires right where they exit the body. I will likely change this some time myself in the future.

Read and understand the instructions. You have to press the on/off button to get it to power a completely dead battery, the override light will come on. I assume this is due to the reverse polarity safety circuitry. There are basic instructions printed on the back of the unit. This is my second one. I've also had it charge from a weak battery and not power up to jump, just remove the negative clamp and reattach usually gets it working. I've been a mechanic for over 45 yrs. and these are one of my favorite tools. What a great innovation. No more jump box batteries losing capacity or having to charge them up for hours after jumping a car. These ultra-caps (capacitor) jump starters charge in about a minute depending on the voltage of the weak battery. Less if charging from a fully charged donor battery. Plus, it's lightweight and compact, I put it with my jack tools under the back seat of the SUV in a small tool bag.

First one I received did nothing when hooked up, and I wasn't connecting it to a totally flat battery, still at 11V, just needed a boost. I could see a couple of the LEDs in the voltage scale were out of place, so maybe some rough shipping, not sure.Second one, started charging when hooked up, but after, say, half a minute, a spark would pop from the black lead connected to the car frame and the unit would stop. Gave it a second try and the fault light came on. Gave it a third try and fault cleared, charging began, spark from the negative lead again, to the point that the lead actually jumped and change position slightly.A friend has also purchased one when I did. We tested hers in the same manner on her car and got the same result. Starts off as it should, then big spark from black lead. Also sent that one back. That's three, I think enough of a test to be done with this one.

I got the 550 amps original jump starter (js) RZ-550 from Rezervo a few years ago and the thing is a beast and works fine. Never had an issue with it. So my sweet wife always wanted one too and therefore we ordered this one here which has 100 amps less. But is also a lot cheaper. If the battery is completely empty then it won't help. But if you have still some power in there and just not enough to start by itself that js will definitely help starting it! Otherwise it can be used to charge it elsewhere and "pump" some energy into a depleted battery until it will start. Good for people who have their trucks/cars just sitting in the driveway with depleted batteries every now and then. If it doesn't start directly, just get the js charged with the other truck/car and "pump" it into the depleted battery.Of course if your starter, relay or something else is the issue it won't help though.Regarding reliability of this one here we shall see. But we checked it twice and it works fine so far. I just take off one star for the reason the charging consumes more time than advertised (100 sec.). Rather calculate with 5-10 minutes unless your battery is full (in which case you won't need a js). This one here also loses power faster than the Rezervo one. The Rezervo maybe loses 1v in a day. This one here loses 2v in a day. So the leakage of the used super caps seems a little higher.In regards of comparison to a battery js I'd definitely recommend a supercap js! You still have the ability to charge it elsewhere (and fast) and if the battery is not completely empty you can charge it on the car/truck where you need it. Easy and simple!