I have been really tempted to buy one of these, because I think they are neat, not that I actually need one. Perhaps for jumpstarting others, as I do not carry cables, nor am I always willing to move my vehicle in such a manner as to jumpstart another. I also would not allow another person to handle the cable ends, as far too many do not understand polarity and will fry the donor vehicle with their ineptness..
As with lead acid batteries, the number of cycles depends on how they are treated. Lithium batteries actually degrade faster when stored at full charge. Lithium batteries also lose a bunch of capacity in cold temperatures. more so than lead acid batteries.
These lithium packs should also not be left to roast in a closed vehicle in summertime.
Some of these claim to be Lifepo4, and others that do, likely use 18650 Lico cells, like are in most laptop batteries and Tesla vehicles. The LiCo can be more energy dense, the LifePo4 safer. I have not yet found any websites where one of these units is dissected and closely inspected.
If any Lithium battery catches fire/starts smoking, the fumes are very toxic with lung damage likely if in an enclosed vehicle. Fires are most likely when charging, and charging of batteries that have been over discharged. While fires are not common, they cannot be ruled out as a possibility. Lead acid batteries can explode too. I do not know how effective the BMS's are inside these jumper packs to keep them from overcharging or overdischarging, or disconnecting them if the cells get too hot, or vary too widely in their voltage. All lithium battery packs that have multiple cells have to employ some sort of BMS( battery management system)
There are many many brands of these lithium jumper packs out there, and more everyday, and most all of them way overstate their capacity. There are a couple Amazon reviews by those with the knowledge and the tools to test capacity, and one of these 11000 mah packs measured out at just over 2000 when brand new. Even if they claim 11000 mAh at 5 volts instead of 12+ volts, these Mah numbers are unrealistic.
I don't really know how fast these charge from a USB source, or a 12v source. I don't know how well they would respond to being treated as a small house battery. Do keep in mind how small they are. They are smaller than my 9 cell 18650 laptop battery. I am guessing that most of these jumper packs are using Six 18650 cells which are capable of high discharge current. While the highest capacity 18650 cells are 3400mah at 3.7V, high discharge cells are usually about 2100Mah, and as such, I think any claim of capacity over~ 6300 is unrealistic, and that is at 3.7v, not at 12v.
So, while these are impressive for their small size that is able to crank a small to medium sized engine, I think many translate this impressive cranking ability into a large capacity, and this simply is false. Yes their capacity is larger than what a lead acid battery of similar size or weight would be, but it is nowhere near the capacity that many believe them to be.
The 18650 cells are currently the highest capacity Lithium cell in production. For the size and the weight, the 18650 cells win. These are what Tesla is using hundreds of Cells in series parallel to get a 300 mile range at best.
One of these jumper packs is using perhaps 6 of these cells, and the particular 18650 cells( 18mm diameter, 65mm long) used in these packs are likely nowhere near the highest capacity 18650 cells which are the Panasonic NCR 18650B, though I hear rumors that Panasonic has a 3600mAh cell now.
Will this be able to run your laptop. Sure, perhaps for the same amount of time as the laptop's fully charged 6 cell battery when new.
Will this be able to charge your cell phone. Yes, numerous times.
Will this be able to start your engine? It depends. Mostly yes, but if super cold and the vehicle's starting battery is really drained low, then likely not.
These can add 200 to 400 CCA to the depleted engine starting battery. While some show the unit itself being able to start an engine, I would not expect one of these to be able to start a large cold carbureted V8 by itself.
I am not sure why they have such a wide range of claimed CCA. There should be a large asterix next to this 400CCA number. Like, only in ideal conditions where the vehicle's battery is discharged just below that voltage where it could start the engine on its own.
So like everything, beware of marketing. These have their uses, but I think many will impart superman status to these for their ability to help crank, or solely crank and engine on their own, but they do not have a lot of capacity. They will not replace a regular lead acid battery for house duties at this point.
These are best used as a portable power source, like if you go on a few hour/ few day long hike, using the GPS on your cell phone, and need to recharge the cell phone, or as an emergency power backup for the laptop when you need 3 hours of laptop time and the laptop's battery is only good for 2.5 hours.
As far as jump starting a vehicle.... I think many of these can easily do small engines, especially when they are new. How long they can keep starting engines after they have been aged and cycled many times is an unknown. I'd hate to recommend these, and have the purchaser have complete confidence in one, only to find it inadequate, and that confidence displaced and perhaps dangerously so.
While I am sure there are scenarios where one can use these as a house battery, charging them while driving, and helping to power low draw devices when parked, one is paying a pretty penny for them, and perhaps has way more confidence in them than they should.
If one is powering some "house" devices with one when parked, and one then finds the engine battery to be depleted and needs the jumpstart, then this pack will likely not have enough gusto left to assist the depleted engine battery into starting the vehicle which is what this product was designed to do. The 19v laptop output and USB output are basically Add ons for the marketing department to boost profits.
And as pointed out, Amazon reviewers on such products are quite meaningless. People simply want their purchases to be wise purchases, and the best way to feel wise is by having others agree and purchase the same product. I find very few reviews that are helpful and many positive, and negative reviews are easily discountable by the obvious ineptness of the reviewer on a product they just do not understand the functionality thereof.
For me, acquiring one of these would be a novelty. I'd test it, determine its capabilities, and then likely only use it during those rare times when somebody in a parking lot somewhere needs a jumpstart. Mostly it would be a 120$ paperweight as my 12v Electrical system is already optimized for my usage and for lead acid batteries.
If one does NOT need the lightweight/portability, convenient all in one package, or the bragging rights of a lithium jumper pack, one could get more capacity and CCA from a 12 AH AGM lead acid battery, for 23$
http://www.amazon.com/ExpertPower-1...152&sr=1-1-catcorr&keywords=12+ah+agm+battery
The larger better lead acid jumper packs have an 18 AH version of the AGM battery for 33$.
These can also be charged when driving, but the usual Lead acid battery clauses apply. Slow to charge from 80 to 100%, and need to be returned to 100% every so often, and need to be stored at 100%. Also if charged through a Ciggy receptacle, a depleted AGM battery can blow the fuse when plugged in. One should run a dedicated fused 10 AWG cabling to starter battery for charging such an AGM battery while the engine is running, and make sure to disconnect it when parked.
So I urge people to think twice. The future is lithium batteries. While they are here, now, they are pricey and do not have the capacity that most will believe them to have. These lithium jumper packs are convenient novelties. Their duration/ lifespan is unknown. When used as a Mini house battery, their capacity is so small that unless one is carrying one in their backpack on a hike, then a 23$ 12 AH lead acid battery would be a better choice, at this point.
If spending 120+$ just for a mini house battery, well one can get a 115 AH lead acid marine battery for that much dough.
