Li-ion to jump start a car?

Canuke

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The new lithium-ion jumpstarters

Recently, lithium-ion based car jumpstart units have been hitting the market. http://www.cnet.com/news/pocket-sized-jump-starters/ In addition to these three units, there is also the AntiGravity Batteries Micro Start XP-1, and by now possibly more.

I have one of these, the PowerAll. I haven't risked a teardown, but I can measure the voltage from the 12V jumpstart terminals, and judging from the voltages I find there, these units are using 3.7V LiIon chemistry. The fully charged voltage is 12.6V, exactly 3x4.2V, whereas 4x LifePO4 fully charged would come in at 4x3.6 = 14.4V.... so these are not A123 based.

So are these probably using IMR type cells? Based on reports from users so far, the PowerAll can easily jumpstart 15-20 vehicles on one charge with no ill effects, so whatever's in these can do 200-400A bursts.
 
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ShineOnYouCrazyDiamond

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Re: The new lithium-ion jumpstarters

Based on that burst ability, the information in the link and the size/shape of the units I would say it is using Lithium Polymer packs. Thin flat and long and they can typically put of 50C continuous / 100C bursts. My only concern would be leaving them in a hot car in the summer. Max temp of the packs is 140* and with summer heat I would be concerned about a cell puffing in that heat. Taking that into account it's still a cool item.
 

StorminMatt

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Re: The new lithium-ion jumpstarters

Based on that burst ability, the information in the link and the size/shape of the units I would say it is using Lithium Polymer packs.

Definitely. It seems like there is a general trend these days toward LiPos and away from cylindrical cells (like 18650s). And with the possible exception of LiFePO4 batteries, I can't see a jumper box using cylindrical cells. 3.7V cells DO seem somewhat awkward, since they don't really produce the best possible voltage for something like a jumper box.
 

ShineOnYouCrazyDiamond

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Re: The new lithium-ion jumpstarters

Definitely. It seems like there is a general trend these days toward LiPos and away from cylindrical cells (like 18650s). And with the possible exception of LiFePO4 batteries, I can't see a jumper box using cylindrical cells. 3.7V cells DO seem somewhat awkward, since they don't really produce the best possible voltage for something like a jumper box.

It may seem awkward to use that voltage, but I've measured the voltage of a fews cars while starting them when I had batteries going dead. Under start load I've measure in the low 10V range. As long as the charger can maintain at least 3.4ish volts under load it should be able to start the car. Question is how many starts it can handle in the long-run before the battery starts to degrade and can't hold voltage under load.
 

Timothybil

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Re: The new lithium-ion jumpstarters

Yeah, but unless one goes around looking for someone to jump, how many times is it actually going to get used? My Chevy is 14 years old, and outside of one time when the battery died of old age, I have never had to jump it, and have only jumped someone else about five times. And that was only because my son's car had some weird problem with the wiring.
 

Timothybil

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Re: The new lithium-ion jumpstarters

I will admit I had to jump my Chevy Lumina van a few times because the kids left one of the dome lights turned on, but I got smart and bought an automatic cut-off switch for the battery. If the voltage drops to far on the battery, or if the switch is smart enough to sense that something is left on, it will cut the battery out of the circuit to keep it from being run down. I think some of the newer ones will actually still pass a few milliamps to keep the engine computer and the radio programed, but not pass enough to let the battery drain.
 

ShineOnYouCrazyDiamond

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Re: The new lithium-ion jumpstarters

My big thing (and problem) with the few times I've had a battery completely drain on me - one time I didn't close the trunk completely on a car when I went away on vacation for a full week - is that even if you can jump the battery it'll never be the same again. The deep discharge really kills these car batteries and you will likely end up replacing it anyways. So there are two scenarios where you will need a charger/jumper:
1) Car battery fully drains either through electrical fault or user error.
2) The battery is getting old and can't hold a good charge needing a charge once in a while.
In either scenario you will need to jump maybe a few times and will end up buying a replacement battery anyway.
 

Canuke

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Re: The new lithium-ion jumpstarters

I completely agree. It's feeding off of peoples paranoia.

That, and the profit margin on these things is huge. The batteries are the biggest cost item by far; the rest is just off-the-shelf buck converters and cabling. That's why everybody and his brother has a battery pack these days, and why their sale prices are 50-90% off when that happens... it's just like the women's clothing market.

At least the "car jumpstarter" ones are probably more robust than the USB-only ones, for the manufacturers who make the effort to live up to advertised spec.
 
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Lynx_Arc

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Re: Battery Jumpstarters

Battery question, has anyone used these things to start a car?

http://www.amazon.com/dp/B00KCD05Y6/?tag=cpf0b6-20

Just curious how they work compared to the SLA packs out there. May be something to throw in my motorcycle saddlebag.
Depending on the accuracy of the claimed capacity and the output of them (wire thickness) they should do fine as many of the car jump start packs use a 12v 12AH SLA battery. I think the difference may be however in the amount of "on demand" current that can be delivered at the moment of cranking the motor. If the battery in the vehicle is just low and can take a charge then it should work fine as it can charge up the original battery some and both batteries together can deliver the required cranking current. A motorcycle most likely takes a fraction of the starting current of a standard auto so a smaller starting battery would do fine. I think some people at one time were using Nicad packs to help start cars as they can deliver a lot of current. Battery size isn't always a determiner of starting current capacity but rather battery chemistry as lithium ion and nicads have a lot more available on demand power. We only use lead acid batteries because they are cheaper to buy and maintain than other types.
 

Gauss163

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Re: Battery Jumpstarters

Im not sure about the item you listed. It does not really seem configured for jump starting given it's capacity rating it seems more for device recharging than high current capacity.

They are built with high-current (RC) LiPo cells, which can indeed supply adequate jump start current. See any of numerous youtube video demonstrations, and many Amazon reviews expressing great surprise that such a small battery can start a car (which shows how little intuition the general public has about the power of Li-ion batteries).

As for the capacity, it is usually exaggerated (typical for Chinese batteries). But capacity matters little for burst-current apps like jump starting.

Btw, some of the Amazon reviews are ridiculous, e.g. see these comments, where the first comment by the seller gives a disingenuous excuse for capacity fraud, and someone swallows hook, line, and sinker, with a bogus gas tank analogy. Perhaps someone with an Amazon account can point them to more knowledgeable forums, e.g. here.
 
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chillinn

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Is lead acid still the best choice for a battery to start a car, today? Why don't cars have a (smaller) battery backup to jump themselves? Looking at how small the new li-ion jumpers are... I wonder how small can they get. Is it possible to jump a car, just once, with something like an A23 (very small 12v) battery?
 
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Lynx_Arc

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Is lead acid still the best choice for a battery to start a car, today? Why don't cars have a (smaller) battery backup to jump themselves? Looking at how small the new li-ion jumpers are... I wonder how small can they get. Is it possible to jump a car, just once, with something like an A23 (very small 12v) battery?

Lead acid is the cheapest choice for batteries for starting a car. I'm not sure of the cost of other packs but I'm guessing it would cost in excess of $100 for a non lead acid battery solution to start a car and could cost several hundred dollars. An A23 couldn't even power the dome light of a car there just isn't enough power in the button cells inside of one to do more than run a wireless remote transmitter for a few seconds or an LED. If you were to put about 400 of them in parallel perhaps you could get somewhere as they use alkaline chemistry which isn't suited for high current output at all.
 

chillinn

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Lead acid is the cheapest choice for batteries for starting a car. I'm not sure of the cost of other packs but I'm guessing it would cost in excess of $100 for a non lead acid battery solution to start a car and could cost several hundred dollars.

Thanks. Don't you think by now that Li-ion could, perhaps should, be an option for the primary start? AND an why not have an option for a backup jumper battery built-in? Lots of expensive stuff on cars these days that are unnecessary, that people pay for, especially in the premium models; leather interior, electric windows & locks, window tinting, superchargers, tires that will re-inflate if pressure too low, televisions, closed circuit video systems with infrared... the list goes on... how many here with pickup trucks have hand-warmers built-in in to their steering wheel? So what is even $500 extra when you're spending $30K-$80K on a vehicle? This is nonsense, unless there are more reasons than cost.
 

WalkIntoTheLight

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Thanks. Don't you think by now that Li-ion could, perhaps should, be an option for the primary start?

No. Not enough max current, compared to lead-acid. You'd need to couple a lithium-ion battery to a supercapacitor (or several) to get enough current. It just ain't worth it. Lead-acid is robust (when kept charged), cheap, and has plenty of power.

AND an why not have an option for a backup jumper battery built-in? So what is even $500 extra when you're spending $30K-$80K on a vehicle?

Because you could buy 5 primary lead-acid starter batteries for that cost, and each one would last longer than your lithium-ion jumper. When lithium-ion are kept at full charge (which you'd probably want if you needed to use it as a jumper), they won't last much more than 3 years. A good lead-acid battery will give you at least 5 solid years of use. So by the time you need to use that jumper on your old lead-acid battery, it wouldn't work anyway!
 

Lynx_Arc

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Thanks. Don't you think by now that Li-ion could, perhaps should, be an option for the primary start? AND an why not have an option for a backup jumper battery built-in? Lots of expensive stuff on cars these days that are unnecessary, that people pay for, especially in the premium models; leather interior, electric windows & locks, window tinting, superchargers, tires that will re-inflate if pressure too low, televisions, closed circuit video systems with infrared... the list goes on... how many here with pickup trucks have hand-warmers built-in in to their steering wheel? So what is even $500 extra when you're spending $30K-$80K on a vehicle? This is nonsense, unless there are more reasons than cost.
What walkinto said
Here is a site that sells lithium ion batteries capable of starting a car.
http://lithiumpros.com/product-category/12v-batteries/
 
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