Lithium battery powered jump start packs.

[KinzeMech]

I've been watching the lithium battery based jump starter offerings for the last few years, and I'm getting real close to finally buying one. Has anyone read any really informative comparison on various models, or have any input about models to get or models to avoid? I also understand these are all lithium based batteries, but there are further differences from there, such as lithium ion, lithium polymer, or lithium iron phosphate, and maybe more. I'm just beginning my research on that but welcome input about pros/cons of each battery type as well.

The first one I'm just looking for something I can throw in the glovebox and my wife or teenagers can use. I understand they all have reverse polarity protection, making them relatively idiot proof. I'm not calling my family idiots, but you know how it is. I've told them red is positive, black is negative, don't cross them, but I also know how well these people listen to me when I'm talking, and worry about their safety (and the vehicle electronics!!) if they were handed a traditional set of jumper cables. It doesn't have to be the most powerful, but does need to start a SUV with a gas V8.

Pending a successful experience with the first one, I might look to one large enough to boost a dead tractor. Although that seems to take them from the just under $100 range to the somewhere over $200 range, AND price on these things the last few years has been falling like electronics, I'm inclined to get the expensive one later, expecting it will likely be cheaper by then as well.

 

[kblee27]

Most of them do not have reverse polarity protection.
Noco genius does.

 

[KinzeMech]

That's good to know. I certainly haven't looked at all of them, but the ones I have looked at indicated they had this feature. I will definitely make sure my final selection does.

 

[katiexoxo]

Do Lithium-Ion jump starter packs really work? I've seen some videos on youtube that imply they do, but they are made but people who get the products for free in exchange for a review and I don't trust them.

I heard that a car needs at least 400 amps to start. How can a lithium-ion pack provide that much current? A li-ion cell has the ability to give like 2A, and that only at 3.7V. So you'd need A LOT of cells to make a starter pack that is able to provide 400A at 12V.

Another thing I heard is that lithium-ion cells don't work well in cold weather, but that's usually when you need to jump start your car..

 

[KinzeMech]

They're not all lithium-ion. There's lithium polymer, and lithium iron phosphate.

Lithium ion is just a chemistry type. Battery chemistry determines what voltage a cell will produce. That is unchangeable. Most everything else depends on the design parameters of the battery (capacity, discharge rate, etc). Most Li-ion are capable of much greater than 2A discharge rate.

The cells in these types of devices have undoubtedly been designed to discharge their capacity very quickly. A typical car battery in good condition can put out 400 amps and maintain that level of output for minutes if necessary. These jump pack batteries are seeking to maintain that output for seconds at most.

It's tough to say exactly how many amps an engine needs to start. It might take a spike of 1000 amps for a split tenth of a second as it begins turning. I have tested batteries or starters in the car by unplugging the fuel pump relay and just letting the motor crank with a clamp ammeter on the starter wire. In the split second it begins spinning, the meter spikes out of range. If I let the motor just continue to crank, a lot of times it doesn't draw more that 250 amps.

I don't think it's a question of whether or not they work, but which ones work better, and how long they might last. It's still a relatively new technology.

 

[theoldwizard1]

Do Lithium-Ion jump starter packs really work? I've seen some videos on youtube that imply they do, but they are made but people who get the products for free in exchange for a review and I don't trust them.

Your statements are correct, but there have been SO MANY videos made, most by people who paid for the products that the answer has to be, "Yes, they work !" ... within some limits.

I heard that a car needs at least 400 amps to start. How can a lithium-ion pack provide that much current? A li-ion cell has the ability to give like 2A, and that only at 3.7V.

400A may be a peak instantaneous current, but the average current is much less. There are Li-Ion cells design for high current/fast discharge, but even though I have a background in electronics, but I can not explain how such a huge amount of power can be extracted from those small cells.

Another thing I heard is that lithium-ion cells don't work well in cold weather, but that's usually when you need to jump start your car..

If you live in a cold climate (where temps regularly get below 32F/0C) then storing it inside your car might not be a good idea !

 

[GTO]

Do Lithium-Ion jump starter packs really work? I've seen some videos on youtube that imply they do, but they are made but people who get the products for free in exchange for a review and I don't trust them.

I heard that a car needs at least 400 amps to start. How can a lithium-ion pack provide that much current? A li-ion cell has the ability to give like 2A, and that only at 3.7V. So you'd need A LOT of cells to make a starter pack that is able to provide 400A at 12V.

Another thing I heard is that lithium-ion cells don't work well in cold weather, but that's usually when you need to jump start your car..

This one does,ask me how I know.
https://www.nationaltoolwarehouse.c...-P48201.aspx?gclid=CKfuvYWh-dECFYeFswodVb4Kkw

 

[tvtaurus]

How do you know? And that is a full sized version not one of the micro cellphone-sized versions.

 

[kblee27]

Lithium jump starter works, but not 100% of the time.
It depends on the condition of the battery.
Most of the time, it will be successful for your gas engine.
But starting a diesel engine is highly unlikely, unless your jump starter is huge.

I jump start cars countless times.
When it comes to diesel, I usually end up with a set of cables and regular lead-acid battery.

 

[katiexoxo]

ok I understand that a cell can be discharged at high rates, say 20A? And that some get wired in series and some in parallel to achieve the desired specs. But the math doesn't seem to hold up. For 400A peak discharge you need 20*20*4 cells, assuming 2Ah @ 3.7V.

 

[theoldwizard1]

They're not all lithium-ion. There's lithium polymer, and lithium iron phosphate.

I would say it differently. They are ALL lithium-ion, but the actual chemistry and physical size/shape of the batteries differ greatly and are CHANGING almost daily !

The most common batteries uses lithium-cobalt electrolyte, but there are dozens (hundreds ?) of variation of that electrolyte and of the anode and cathodes. The most common physical cell is the 18650 (18 mm diameter, 65.0 mm length).

Lithium-polymer just means that the electrolyte, anode and cathode are inside a a soft polymer "pouch", which can be made into almost any size/shape. This is what is inside most (all ?) cell phones and tablets.

One of the older chemistry is lithium-iron-phosphate (LiFePO4) or simply LiFe. It produces lower voltage (3.2V), but pretty much exempt from traumatic over charging/discharging.



If I was shopping for a portable jump starter, one that uses LiFePO4 batteries (like the one from HF) would be hogh on my priority list.

 

[theoldwizard1]

But starting a diesel engine is highly unlikely, unless your jump starter is huge.

I think the problem with diesels is the amount of energy required for the glow plugs.

 

[mrjaw14]

Perhaps I can add some clarification. They aren't "batteries" like a cell phone battery. They more closely function like a capacitor. High discharge current for a short time. The lithium ion part is just the chemistry. Lion/Li-polymer can store a charge for a while, so it's becoming the preferred chemistry. The older jump packs just had a sealed lead-acid battery in them. Very small compared to the vehicle's normal cranking battery. The jump packs on the market today are just the smaller next generation of that.

 

[SuzukiGS750EZ]

Check out powerall. i love mine.

 

[kctyphoon]

One of the best names in jump packs is Anitgravity. You can find them on Amazon.

Also, harbor freight just recently started selling a new Lithium Iron jump pack. So far it has gotten very good reviews. With an item specific coupon, I think you can find it for $69.


Anyway, if you look at 18560 batteries that are sold online for vape kits, they have some rated for a constant discharge rate up to 35 and 40 amps.

Here, if anyone can understand this -
http://www.powerstream.com/18650-high-discharge-rate.htm

 

[kctyphoon]

I think the problem with diesels is the amount of energy required for the glow plugs.

I think the bigger problem with diesels is the compression ratio.. 17:1 is not easy to crank..