# Is this possible? (18650 5AH cell?)



## Genius Pooh (Dec 23, 2011)

http://www.ebay.com/itm/20x-18650-3...US_Rechargeable_Batteries&hash=item27c91e8827

At Ebay show amazing cells 

5000mah ...wow?

they said It's from japan??

Is this possible?

What is best way check this battery's real AMH?

Hmm very supicious...


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## Ziggythewiz (May 16, 2010)

Shouldn't be too unreasonable. That's less than double where they were 10 years ago.


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## major (Apr 4, 2008)

Genius Pooh said:


> What is best way check this battery's real *AMH*?


Hi Pooh,

AMH  I think you mean capacity in Ampere hours or Ah. Please use the correct units.

And the only way to really check "real" capacity or Ah of a battery or cell is to test it. And test a sample lot, not just one. Sometimes you can find independent agency test data.

Also note that Lithium cell chemistry and construction can be tailored to high energy or high power, but rarely for both together in an affordable package with respectable life. 

Regards,

major


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## PStechPaul (May 1, 2012)

It seems like a good deal. Maybe too good to be true. 20 pieces of 5 A-H cells at 3.7V is 370 W-H, for $66 including free shipping? That's $178/kW-Hr, which is about half the cost of the Turnigy packs on the Hobby King site. 

There's also 10pcs of 4000 mA-Hr cells for $20:
http://www.ebay.com/itm/10PCS-LOT-1...=755585581324274803&pid=100009&prg=1004&rk=1&

That's $135/kW-Hr. Sounds like an incredible deal. But I don't quite trust them.


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## Genius Pooh (Dec 23, 2011)

major said:


> Hi Pooh,
> 
> AMH  I think you mean capacity in Ampere hours or Ah. Please use the correct units.
> 
> ...


Thank you but what I said is just about real test instrument...

What is best and cheap way?

And is it real? 5ah??


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## Genius Pooh (Dec 23, 2011)

PStechPaul said:


> It seems like a good deal. Maybe too good to be true. 20 pieces of 5 A-H cells at 3.7V is 370 W-H, for $66 including free shipping? That's $178/kW-Hr, which is about half the cost of the Turnigy packs on the Hobby King site.
> 
> There's also 10pcs of 4000 mA-Hr cells for $20:
> http://www.ebay.com/itm/10PCS-LOT-1...=755585581324274803&pid=100009&prg=1004&rk=1&
> ...


Yeah me too I can't trust them.... 

Tesla's new car use panasonic 18650 cell 7 thousand..Hmm If this battery is good why they use panasonic's ??

And I heard LG 's best one is just 3.3ah ..hmm


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## PStechPaul (May 1, 2012)

You can fairly easily make a constant current load from a power transistor, diodes, and resistors. Set it for 5 amps and use a datalogger to record voltage and current for one hour or so. I am not so concerned about the actual A-Hr rating, although it is important. But these cells are rated at 1000 cycles, and I'm afraid that well before then, they will start losing capacity or have other problems. And the biggest concern is basic quality of construction and safety. There is a very real "potential" for danger if Lithium cells fail catastrophically. I can draw up a simple load tester if you want to conduct some tests.


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## major (Apr 4, 2008)

Genius Pooh said:


> Thank you but what I said is just about real test instrument...
> 
> What is best and cheap way?
> 
> And is it real? 5ah??


http://www.westmountainradio.com/product_info.php?products_id=cba3&navcode=/UPSCBA 

Get one of these and find out


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## dreamer (Feb 28, 2009)

PStechPaul said:


> It seems like a good deal. Maybe too good to be true. 20 pieces of 5 A-H cells at 3.7V is 370 W-H, for $66 including free shipping? That's $178/kW-Hr, which is about half the cost of the Turnigy packs on the Hobby King site.
> 
> There's also 10pcs of 4000 mA-Hr cells for $20:
> http://www.ebay.com/itm/10PCS-LOT-1...=755585581324274803&pid=100009&prg=1004&rk=1&
> ...


Even more unbelievable, these 3600mAh cells are only 50 cents apiece:

http://www.alibaba.com/product-gs/5...00mAh_18650_Rechargeable_Battery_Yellow_.html

Not only would 5,000 cells give you a 55kwh battery pack for $2,500, but the weight is supposedly only 49g per cell. So it would only weigh 245kg. Doesn't quite jibe with prismatic cells that would typically weigh 600kg for that size pack and cost $20K.


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## Ziggythewiz (May 16, 2010)

Why are you comparing Li-ion to LiFePO4?? It's well known that Li-ion has higher energy density, but the cycle life doesn't even compare. Li-ion can get 300-500 cycles, or some as much as 500-1000 cycles, while LiFePO4 will do 2000-5000.

UltraFire cells have always been cheap, and often live up to their name.


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## PStechPaul (May 1, 2012)

Ziggythewiz said:


> Why are you comparing Li-ion to LiFePO4?? It's well known that Li-ion has higher energy density, but the cycle life doesn't even compare. Li-ion can get 300-500 cycles, or some as much as 500-1000 cycles, while LiFePO4 will do 2000-5000.
> 
> UltraFire cells have always been cheap, and often live up to their name.


Excellent point! I did not know the differences between LiFePO4 and Li-ion, and I think there may be other variations as well. The $8, 34 W-Hr pack ($0.23/W-H) from Hobby King is LiPo:
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=8932

And they have a $25, 38 W-Hr LiFePO4 pack which is $0.66/W-Hr.
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=16590

So if the LiFePO4 will give 3x the life it's a wash, except for time and hassle of replacement. The cheap cells add the "free fireworks factor", or FFF rating!


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## major (Apr 4, 2008)

PStechPaul said:


> Excellent point! I did not know the differences between LiFePO4 and Li-ion, and I think there may be other variations as well. The $8, 34 W-Hr pack ($0.23/W-H) from Hobby King is LiPo:
> http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=8932
> 
> And they have a $25, 38 W-Hr LiFePO4 pack which is $0.66/W-Hr.
> ...


You guys should not make generalizations from a single dealer web site spec sheet.

*Lithium ion *describes a family of battery which includes LiFePO4. Ref: http://en.wikipedia.org/wiki/Lithium-ion_battery Also good info at http://batteryuniversity.com/learn/article/types_of_lithium_ion 

On amateur sites like this, the Lithium chemistry is typically broken in two areas, LiFePO4 and LiPoly (or Lipo). The LiFePO4 typically has an OCV nominal of around 3.2v and comes in prismatic and cylindrical cells (and pouch just recently) from the likes of A123, Calib, Thundersky, Headway, etc. LiPoly typically have an OCV nominal of about 3.7v and come in pouches (and small cylinders). I use some of the larger LiPoly from Kokam and EnerDel.

You can not apply across-the-board generalizations concerning performance, safety and life. Afterall, most of the OEM automotive EV and PHEV batteries have been the LiPoly with warranties of 7 to 10 years which certainly blows your cycle life statement away and also shows a high confidence about the safety.


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## Ziggythewiz (May 16, 2010)

Typically a cell that is LiFePO4 will say so on the website, while those that just say Li-ion are the more generic LiPoly

As for cycle life, the numbers I listed are from published manufacturer specs. I have not seen any web offers for LiPoly with cycle life comparable to LiFePO4. Auto manufacturers can warranty whatever they want. They heavily restrict the available DOD and charge for longer life, and have good reason to offer warranties that may last longer than the cells do.


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## rochesterricer (Jan 5, 2011)

Are most of the Lipoly cells that people buy from RC suppliers of the Lithium-Cobalt chemistry? I'm just guessing on this based on the higher nominal voltage.


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## major (Apr 4, 2008)

Ziggythewiz said:


> Typically a cell that is LiFePO4 will say so on the website, while those that just say Li-ion are the more generic LiPoly


It is the other way round. Look at reference links I provided. LiFePO4 is a subset of Li-ion.



Ziggythewiz said:


> As for cycle life, the numbers I listed are from published manufacturer specs. I have not seen any web offers for LiPoly with cycle life comparable to LiFePO4. Auto manufacturers can warranty whatever they want. They heavily restrict the available DOD and charge for longer life, and have good reason to offer warranties that may last longer than the cells do.


Are you kidding? You think automotive OEMs will offer warranty knowing the product life is less than the term? I don't think so.

Kokam specifies a minimum cycle life of 2000 at 80% DOD. 

My point was stated. The generalized statement you made about cycle life of 300-500 is BS.


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## lithiumlogic (Aug 24, 2011)

My BS counter is off the scale on this one. I've seen a few cordless drills with LiFePO4 18650s , rated for 1300mah.

Lithium Cobalt laptop 18650s range from 1800-2400mah in tests run by flashlight enthusiasts. Some (typically lower performing) cells get rebranded as "Ultrafire" or other makes you've never heard of and sold with a wildly optimistic 3000mah rating.

The Tesla Model S, with the top end 85Kwh pack, uses new state of the art Panasonic NNP cells with an actual 3000mah capacity. These are basically lithium cobalt, but acheive higher energy densities than ever before with a bit of added Nickel and Mangansese.

Next year, Panasonic reckon they can push to 4000mah by swapping the carbon anode for a silicon one. The downside is that the cells will weigh more too and not actually give any more Watt/hour per kilogram.

Then along comes this offer on ebay of cells with 5000mah rating - with not even a press release from the OEM that must have made such a breakthrough?


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## Ziggythewiz (May 16, 2010)

major said:


> It is the other way round. Look at reference links I provided. LiFePO4 is a subset of Li-ion.
> 
> 
> 
> ...


MY point, was that if you see Li-ion listed for a battery, you should assume LiPoly, not LiFePO4. In this case, at 3.7V and up to 1000 cycles, I guarantee it is not LiFePO4.

OEM's can't offer too short warranty or they won't sell cars. People need warm fuzzies, especially with EVs and expensive batteries. At the price they're selling, they could even have a 2nd pack built into the sticker price. A typical warranty is also non-transferrable so as long as your pack doesn't die before you sell the car (typically in 3-5 years) they win.

Nissan and Tesla have their owners come in for regular checkups where they run battery diagnostics and replace weak cells. If you weed out the weaklings early, it will greatly extend the health of the group. Also, the warranties are mileage capped, so you could easily run it out in 4 years for the Leaf.

Please provide a link to order Kokams.

Laptop batteries have typically lasted 300-500 cycles for many years. I didn't realize the most common use for a cell counts as BS.


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## major (Apr 4, 2008)

Ziggythewiz said:


> MY point, was that if you see Li-ion listed for a battery, you should assume LiPoly, not LiFePO4.


I see LiFePO4 referred to as Li-ion often and that is the way this terminology is listed on those web sites and other places. You can make assumptions you like and tell others they should assume the same. I can warn them that it is not universally accepted.



> In this case, at 3.7V and up to 1000 cycles, I guarantee it is not LiFePO4.


Never said it was.



Ziggythewiz said:


> Please provide a link to order Kokams.


http://www.dowkokam.com/tech-cells.htm



Ziggythewiz said:


> Laptop batteries have typically lasted 300-500 cycles for many years. I didn't realize the most common use for a cell counts as BS.


What counts as BS is your statement which implies all Li-ion.


> Li-ion can get 300-500 cycles, or some as much as 500-1000 cycles,


 Yes, maybe some do, but there are many Lithium Polymer cells with higher cycle life.


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## Ziggythewiz (May 16, 2010)

major said:


> http://www.dowkokam.com/tech-cells.htm


Where's the order page?


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## major (Apr 4, 2008)

major said:


> I see LiFePO4 referred to as Li-ion often and that is the way this terminology is listed on those web sites and other places.


 


> To complete the list of popular Li-ion batteries, the table also includes NCA and Li-titanate, two lesser-known members of the Li-ion family.
> *Chemical name*
> *Material*
> *Abbreviation*
> ...


From: http://batteryuniversity.com/learn/article/types_of_lithium_ion 
See the web site for a better looking table. It didn't copy and paste well.

As you can see, *Li-ion* refers to the whole group which includes Lithium Iron Phosphate.


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## major (Apr 4, 2008)

Ziggythewiz said:


> Where's the order page?


If you're a serious buyer, contact them and I am sure they will accommodate your order.


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## Ziggythewiz (May 16, 2010)

So no order page, huh? It's almost like kokams aren't your typical li-ion battery...


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## major (Apr 4, 2008)

Ziggythewiz said:


> So no order page, huh? It's almost like kokams aren't your typical li-ion battery...


huh Typical li-ion battery  What are you talking about? 

There is no typical Lithium battery. There are many different types in the Li-ion family including Kokams and LiFePO4.

I suggest we end this pissing match


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## Ziggythewiz (May 16, 2010)

major said:


> huh Typical li-ion battery  What are you talking about?
> 
> There is no typical Lithium battery. There are many different types in the Li-ion family including Kokams and LiFePO4.


I'm just trying to say that a typical (as in average) li-ion (LiPoly) will have higher energy density, but less cycle life than a LiFePO4 cell. One of your own links even says "400-1200"

And I'm no expert on top of the line li-ion, but I'm pretty sure Kokam is a brand, while LiFePO4 is a chemistry.



major said:


> I suggest we end this pissing match


Agreed


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## dladd (Jun 1, 2011)

Ziggythewiz said:


> I'm just trying to say that a typical (as in average) li-ion (LiPoly) <snip>


this is the point Major is making. Li-ion does not equal LiPoly. Li-ion is a vast range of chemistries, including both LiPoly AND LifePO4.


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## DDDvvv (Apr 2, 2012)

back when they released the 3800mAh version of the 18650 on ebay, some battery expert at the candlepower forums took a plunge and tested them. the results were horrific!! nowhere as close as advertised. more like 2200mAh and a poor discharge curve.

so it makes me wonder if this is a repeat performance by the sleek hong kong traders. they probably figured out that given a choice, folks would trust a product from japan first, before china.

im looking around for a good battery deal, and i wouldnt spend thousands on this, unless i get some proper and promising test results.


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## Genius Pooh (Dec 23, 2011)

major said:


> I see LiFePO4 referred to as Li-ion often and that is the way this terminology is listed on those web sites and other places. You can make assumptions you like and tell others they should assume the same. I can warn them that it is not universally accepted.
> 
> 
> 
> ...


 
new type of cell can yo tell me price and spec of it?


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## major (Apr 4, 2008)

Genius Pooh said:


> new type of cell can yo tell me price and spec of it?


Contact Kokam. I think they have manufacturing facility in Korea.


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## Genius Pooh (Dec 23, 2011)

major said:


> Contact Kokam. I think they have manufacturing facility in Korea.


 
Hmm OK Kokam is Korea brand name I don't know that's that...


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## dreamer (Feb 28, 2009)

lithiumlogic said:


> My BS counter is off the scale on this one. I've seen a few cordless drills with LiFePO4 18650s , rated for 1300mah.
> 
> Lithium Cobalt laptop 18650s range from 1800-2400mah in tests run by flashlight enthusiasts. Some (typically lower performing) cells get rebranded as "Ultrafire" or other makes you've never heard of and sold with a wildly optimistic 3000mah rating.
> 
> ...


The Tesla Model S uses an 84kwh battery pack and says 7000 cells. That means each cell is 4000mAh. Are you saying they are knowingly falsifying their specs and know those cells will only deliver 3000mAh ?

I've done a little research on these Ultrafire cells, and while I didn't find anything on real-life cycle life, I did find some other good reasons not to use them. They have a high self-discharge rate, and lose more than half their charge when sitting for just two weeks. They also have a low max discharge rate of under 2C, meaning you'd need a very large kwh pack to drive an EV with any sort of performance.

The Tesla S uses such a large battery pack that they can afford to use cells with a low max discharge rate of only 3C and still produce the 300+hp they claim. Few of us could afford to build an 84kwh battery pack unless some of these sub-$1 3000mAh cells are actually any good. But you can understand why cycle life is less important -- even 1000 cycles in a car with 250 mile per charge means 250,000 miles before battery replacement.

It is intriguing to think of a 300Ah cell made up of 100 small 3000mAh cells that fit in an 8" square box only 3" tall and weighing only 5kgs and cost under $100.


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