portable jumpstarter ？

[elhigh]

I have yet to find a jumper pack that worked on our vehicles here at work. I had one that got tried on four different cars and two different trucks (at various different times), and I always made sure the pack was charged. No joy, not even once. I recycled it.

On the other hand, the jumper cables in the maintenance truck work great.

[Nautilus]

Originally Posted by vskid3

Am I the only one seeing the last picture? It looks like you can clamp it to the battery like a regular jump box and start the car that way. Still might not be good enough for a stone-cold dead battery and large engine, but would probably be fine if the battery is just on its way out. I think there's some poor translation or too much dumbing-down in the instructions.

A pocket lithium jump starter can and will start a gasoline engine in the 2 liter range, if clamped directly to battery terminals. But not in the form it's sold in stores or Amazon. As it comes from factory, it has a pack of Schottky diodes on the + wire, to protect from reverse polarity. Ordinary, board soldered Schottky diodes. A 200 amp diode is 10 times bigger and looks nothing like a board soldered diode.

So the board of diodes has to be removed and replaced with a solid copper bar. Once this is done, a 5.8Ah lithium jump starter can give "a kick" to a weak battery and turn the starter motor. After 2 starts, its charge barely falls from 4 LEDs to 3. On a dead battery it may struggle, or not be able to turn the starter motor more than a few turns.

The jump starter is less than 1/2 lbs and it can be easily held in a coat pocket, like a big smartphone.

Wires are 10 AWG, too thin to carry current for a sizable amount of time, but enough to fire a burst of current for 1-2 seconds, as needed for a jump start.

Due to being cheap and very lightweight, it's a good addition to have in the car if you are stranded somewhere with a weak battery.

[ThermionicScott]

It's too bad that the option of manual crank-starting went the way of the dodo long ago. Now there's a simple, cheap, direct way of cranking an engine over, if you know what you're doing.

[jakobnev]

Hand crank is back:

https://www.youtube.com/watch?v=1pnXaENvCKc

[Stubby79]

I've had/have a couple that use an 18ah SLA battery, and they will make up the difference if your battery is a bit too weak to crank over. Completely dead? Probably not, though I have hooked one directly to a starter on an engine that's out of the car and cranked it over just fine, as long as the battery pack was fully charged.

I had one with a smaller, 7ah battery in it. It could help, but wasn't really enough to make a big difference.

I h ave one of those mini lithium ones. I haven't had to use it yet, so couldn't attest to how useful they are. It only has 10-gauge wires on it, so I don't expect it'll put out more than 50 or 100 amps, whatever it might actually be rated at (400?).

Again, the big, heavy SLA ones (~18ah) work fine on 4 bangers, or even 6s.

[Nautilus]

Even through 10-gauge wires, the lithium battery can fire a short burst of current, for 1-2 seconds, as needed for a jump start. But not through diodes on the wire, these have to go away.

Inside there are 3 x 3.7 volts lithium batteries, as used on tablets and bigger smartphones, wired in series. They can give, depending on size, 3900 to 8000 mAh (less than nominal, 5800 to 12000 mAh).

Lithium batteries can discharge in one burst, like a supercapacitor. This is one of the reasons they are so dangerous and catch fire so easily. Sluggish lead-acid batteries can't put out the needed amps quick enough.

[RedDevil]

I got myself this Li-ion compressor and jump starter.

The compressor is the #1 application I got this for.
No more fiddling with the stubborn wire to the 12V plug on the Honda compressor which is very stiff when cold.
No more fiddling with the screw-on nipple which always leaks; this one has a proper lever.

And it can jump start the car, shine a light and charge my phone 7 times over.

Top brand too: Ultimate Speed, not Initial Mass or Intermediate Reliability... Only the Besth!


Hardly any bigger than the original compressor that came with the tire sealant kit in the car.
Much smaller and lighter than the starter cables I took out of the trunk.

[mattrod]

I have a Quipall jumpstart. It was a gift. I keep it in the trunk of my car.

[Stubby79]

Turns out my lithium jump pack is done. Never really used it. Failed to help jump start my car the one time I tried to use it a few months back. Discovered it was toast when using the USB ports to recharge something...it only lasted a few minutes before being depleted, when it should have lasted hours.

Not planning on replacing it. Not much point if they'll crap out before getting used.