# prismatic cells durability (discharge)



## Matter45 (Jan 2, 2013)

Does anyone know how much discharge (3C or more) prismatic cells can endure before they start to fail or loose capacity?

Im setting up a system that is capable up to 1000A (4C out of the prismatic cell battery pack). I do know from reading other posts that 0.3c and 70% DOD is the best way to extend battery life 10+ years. But wat if i pull 1000A like once a month? I guess what I am asking is if there is an expert on prismatic batterys in doing durability discharge tests and seeing how many life cycles these batterys have at 4C.

I will be happy if the life cycle is 2000 even at 3C.

Or maybe only do 3C - 4C after the battery pack is fully charge? I do understand that voltage of the prismatic cells have a relation to durability. Bringing the voltage down by discharging can reduce the life cycle?


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## Ziggythewiz (May 16, 2010)

Matter45 said:


> 0.3c and 70% DOD is the best way to extend battery life 10+ years.


How do you know that? No one's had these cells for 10 years. I don't think 3C should be an issue for any of the big brands though. They're all rated higher than that.


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## rwaudio (May 22, 2008)

Matter45 said:


> Does anyone know how much discharge (3C or more) prismatic cells can endure before they start to fail or loose capacity?
> 
> Im setting up a system that is capable up to 1000A (4C out of the prismatic cell battery pack). I do know from reading other posts that 0.3c and 70% DOD is the best way to extend battery life 10+ years. But wat if i pull 1000A like once a month? I guess what I am asking is if there is an expert on prismatic batterys in doing durability discharge tests and seeing how many life cycles these batterys have at 4C.
> 
> ...


Which prismatics are you talking about?
Any of the newer ones should be fine. Some of the older ones might not like it as much, but 5-10 second bursts at 4C should be fine for almost any prismatic unless it's the 1C Hipower cells or something similar.


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## Matter45 (Jan 2, 2013)

can anyone suggest the "big brands"? This is something that no one want to get wrong so even though I may know the answer of who the "big brands" are, can we name a few?

Also is there anyone out there who have had these cells for a long time (since they came out) and are still experiencing good performance out of them in regards to discharge rate and capacity? I have been told by someone that if you discharge consistantly at 3C, after about one year they start to degrade.

Its sad that we have to relie on prediction data. I wonder if anyone has any cycle count data on any prismatic cells...

Does anyone feel the same as I do? It scares me to make such a high investment in something that hasnt been proven. Maybe im being paranoid, maybe im not. Tesla's battery pack is proven technology in regards to robustness, durability and peak output.

I suppose what im after is as much information as possible before I make the leap of faith. Maybe I should buy one cell and test teh hell out of it and post the information online for all to see for each brand... Can anyone suggest any website out there with real hard cycle life data? I can only find data with 10% discharge rate at the cells maximum continuous output (0.3c)

CALB
WINSTON
THUNDERSKY
SKY ENERGY

These are the brands I have seen. Any others?

Thank you in advance for your support


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## Ziggythewiz (May 16, 2010)

You've mostly got them. Sky became CALB. Thundersky became Sinopoly and Winston.

The only people who could have more than a few years experience with these would be with the early gen TS cells, which are much different from the cells of today.

.3c is not the maximum continous output for any of these. 3C is pretty typical for a continuous rating, but you're not going to come close to that anyway. If your 4C is 1000A, you'll never be using even 3C for more than 10 seconds.


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## rwaudio (May 22, 2008)

Like Ziggy said, there just isn't much long term data because the cells haven't existed long enough.

Many people have had great bench test results with the CALB CA series when higher discharges are involved. My testing agree's with that but I also don't have any long term testing. 

I'm testing some 3 year old Yellow thundersky 100Ah cells that were used on an oil rig in some harsh canadian conditions with no bms and no heating, the lowest cell came in at 99.22Ah with a 40A discharge. If I had done the recommended 0.3C (30A) discharge I'm sure it would have put out a hair over 100Ah, meeting spec after 3 years of low current use in unfavorable conditions.

This isn't an endorsement for the yellow thundersky's the sag is much worse with these 100Ah cells than it is with the 60Ah CALB CA's under the same test. It's just a data point for some LiFePO4 that's a few years old.


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## Matter45 (Jan 2, 2013)

Thanks guys. Now it is a much smaller leap of faith. Does anyone else out there have any other testing after many years?

Also why did they change there names? Bad reputation maybe? CALB and Winston?


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## rwaudio (May 22, 2008)

Matter45 said:


> Thanks guys. Now it is a much smaller leap of faith. Does anyone else out there have any other testing after many years?
> 
> Also why did they change there names? Bad reputation maybe? CALB and Winston?


I believe Sky Energy became CALB (China Aviation Lithium Battery) when they got funding related to aircraft batteries.

Thundersky supposedly became Sinopoly after the founder(?) Winston Chung left the company to start Winston Battery.

From what I've read CALB and Sinopoly are the two best choices. I went CALB because you can buy them out of a USA warehouse and are typically in stock.


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## Ziggythewiz (May 16, 2010)

rwaudio said:


> From what I've read CALB and Sinopoly are the two best choices. I went CALB because you can buy them out of a USA warehouse and are typically in stock.


Agreed. I favored Sinopoly until I was ready to buy, but CALBs were stateside and I found a good deal.


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## kennybobby (Aug 10, 2012)

*Re: prismatic cells*



Matter45 said:


> CALB
> WINSTON
> THUNDERSKY
> SKY ENERGY
> ...


Bestgo. supposedly formed to produce higher quality cells by some former associates at some of the above companies. i've tested 44 of them for a pack, all perfect. Worth investigating, some folks had shipping issues but we had none.


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## Elithion (Oct 6, 2009)

Matter45 said:


> CALB
> WINSTON
> THUNDERSKY
> SKY ENERGY
> ...


Sky Energy = CALB
THUNDERSKY is no longer: see Winston and Sinopoly

The full list

Alees
Bestgo
CALB
CENS
GBS
Gold peak
GS Yuasa
Heter
Huanyu
k2
Liotech
Lumos
RealForce
Shandong Hipower
Sinopoly
Tenergy
Winston


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## PStechPaul (May 1, 2012)

You may also try Tornado:
http://www.tnd-battery.com/index_en.html

I have received excellent communication and fast, reasonable quotes from them, but I have not ordered any and I don't know their history. Seems worthwhile to add them to the list, though.


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## Elithion (Oct 6, 2009)

PStechPaul said:


> Tornado:... add them to the list, though.


Tornado is just a reseller. It resells cells made by Real Force. The list already lists Real Force cells.


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## PStechPaul (May 1, 2012)

Elithion said:


> Tornado is just a reseller. It resells cells made by Real Force. The list already lists Real Force cells.


I had a hard time finding the website for realforce, and they do not list any prismatic cells. They seem to specialize in battery packs:
http://en.realforce.com.cn/

Tornado describes themselves as a manufacturer, and their website shows manufacturing and testing equipment. They also list a wide range of products from individual pouches and prismatic cells to cylindrical types, and they show test curves. But I don't have any information other than what I can find on the websites. Thanks for the heads up, but it appears to be easier to order from Tornado rather than Real Force.


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## Elithion (Oct 6, 2009)

PStechPaul said:


> I had a hard time finding the website for realforce, and they do not list any prismatic cells.


Here, which I got from the cells page. I am constantly updating it, so please take advantage of it, as it has a lot of info.



PStechPaul said:


> it appears to be easier to order from Tornado rather than Real Force.


RealForce opened a US branch: Powin Energy, in Oregon. If you're in the US, it may be much easier to buy from Powin than from China.

(I am completely disinterested in cell manufacturers; I am doing this as a service to the community.)


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## Matter45 (Jan 2, 2013)

*Re: prismatic cells*



kennybobby said:


> Bestgo. supposedly formed to produce higher quality cells by some former associates at some of the above companies. i've tested 44 of them for a pack, all perfect. Worth investigating, some folks had shipping issues but we had none.


I have an electric push bike with one of their batteries. I have really abused it over a 2 year period, using it just about every day, draining it to 100% DOD on many occasions and it has lost more than 30% of its original capacity. I have to say with the punishment that I have been giving it, I expected it to die off quickly. But it seems that at first, these batteries will quickly loose there max rated capacity even in the lightest conditions, then level off and hold the same capacity (about 60% of the rated capacity) for a longer period of time. I ride it to work and back every day, and I don’t have to pedal as it will make the 15km journey. the discharge is slightly more then 1C.

Using this information, I suggest to keep as low C (discharge rate) as possible, keep the battery about 50% capacity (DOD). Lithium batteries like to be kept at charges between 40% and 60%, especially on the shelf.

in my case, when the electric car is finished, I will restrict the discharge rate, and make it charge to 60-70%, and cut off at 40%. because I would only have to travel 15km a day, this will be easy.


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## corbin (Apr 6, 2010)

Elithion said:


> (I am completely disinterested in cell manufacturers; I am doing this as a service to the community.)


Which is awesome, by the way. Thanks!


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## Karter2 (Nov 17, 2011)

Elithion said:


> The full list
> 
> Alees
> Bestgo
> ...


 Davide,
Just a couple of questions / possible updates for your lists...

1) are you sure K2 manufacture cells ?
.I believe K2 only (possibly ?) assemble modules in CA from chinese made cells.

2) I see no mention of "Herewin Technologies" who are a major producer and supplier to other resellers.
Brands such as "Haiyin" and "Scorpion", possibly even "Turnigy" RC packs..
http://www.herewin.com/en/about.aspx

3) Safty Energy is another primary cell producer also i believe..
www.*saftyenergy*.com/ ( note some problems loading that site ?)
http://www.3dxchina.com/english/showlink.asp?id=8


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## brainzel (Jun 15, 2009)

After 2 1/2 years and >23.000km / 14.300 miles of daily usage of SkyEnergy cells in a electric vehicle, I have no decreasing noticed or measured.
The cells behave just like 30 month ago.
This spring I will measure each capacity of all 45 cells, than I can give you a detailed review.

*btw:*
There are several complaints to the german Sinopoly representation from Sinopoly users.
Reason for this are attributable to production-related leaks.
In contrast to the previous method of production (the plastic housing is welded to the top), the Sinopoly cells now be closed at the bottom.

Could anyone confirm this issue?


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