A123 20AH cells source?

[miernik]

wouldnt the 18650 123s work out expensive also? they would take nearly twice as much space, and weigh double what the 20ah pouches do? -could be wrong but dont the little 18650s have the worst energy density of anything? well below 90wh per kg vs 140wh/kg, and a huge headache to hook up 100's of them.

18650s are the cheapest A123 B-grade cell now, at 2.05 USD a piece, with the lowest price for 26650 of 7 USD they are 2/3 of the price of 26650 in terms of USD/Wh

Not double weight then 20ah pouches, just 40% more.

18650 have 90% of the energy density of 26650, not a big deal if they are 2/3 of the price!

20Ah pouches are interesting, I actually ordered one, but I've seen their max charge rate being stated as only 1C somewhere, if that is true then I'll rather use 18650 despite the weight, because I can charge them at 4C.

And 18650 are in alu tubes, so I guess are more fire-proof and robust then pouches. And I can't imagine at the moment how would I attach the cable to pouches - paper clips or what?
I bought it as a curiosity, but I think for my van (yes, I plan converting a 2165 kg van to EV) I'd use 18650s anyway.

 

[curious]

but, the voltage was 2.38v and that is very unusual..
every one of these cells from cellman etc in the past, have been between 3.34 and 3.35v so i can only hope they have tested this one or something??
maby these are seconds that have high self discharge??
i am charging it now at 10a, it will be done in 2 hours, and i will then get an idea of its capacity, and ill email a123rc with a wtf. :?

capacity report (of charge) and further info due shortly.

My experience with few a123 26650 from dewalt packs that had below normal storage voltage (probably high self-discharge cells) is that they still provided full rated capacity. The packs I've built 2 years ago with few of these still work like new. However IMHO it would be appropriate for a vendor to mark it as B-stock or something...

 

[toolman2]

the capacity came in at 20.204ah,
and remember that was charging, from dead flat (as it arrived)..
so the capacity seems ok (at least 95%ok) at this stage, but looking at the fact that the volts dropped from 3.60 to 3.40 within 10 mins -my guess is that they
have too high a self discharge rate for leaving in an ev for 6 months, and have thus been kindly sold to us
i will soon test it under load (but i am not liveforphysics so the test will be sub 100a) to check ir.

 

[auraslip]

18650s are the cheapest A123 B-grade cell now, at 2.05 USD a piece

Wait really? I thought all those ebay a123s were counterfeit.

 

[webfootguy]

I have not received my cells yet and the status on the website (www.a123rc.com) still says "Confirmed,Payed,Preparing". I have tried multiple times over the last 5 days to contact them about my order but have yet to get any email reply (bad sign? Good sign that they are busy?). I double checked the paypal policy and you have to start the resolution process before 45 days have gone by so I have some time yet (order date is 3/23 and I did get the $40 price so it would be *nice* if they ship). I'm fairly sure paypal will protect me if they can not provide a shipping number but I will give them more days to ship.

Toolman2, did you order your cell from www.a123rc.com or directly from OSN POWER TECH LTD? I got a quote from them but it was higher when you include shipping and they did not take a credit card or paypal, only wire services which make me more nervous. Also, did you have to pay any import fees? Many vendors mark the label as "gift" which seems to avoid the import fees on lithium batteries (I got nailed once for the same lithium battery fees when purchasing some toolpacks from Canada).

 

[jonescg]

Well, are we able to get more of these cells or WHAT?

Toolman - no idea yet if they are the genuine article?

I was working on a simpler termination method for the four spare cells I have using clamps and spacers. I'll put some pics up later on.
CHRIS


PS - For what it's worth, the four spare cells I have each read 3.3 V and they have been sitting around for almost a whole year.

 

[olaf-lampe]

@Chris
The difference of LiFePO and the so called LiPos is, that LiFePO settles down to 3.3V pretty fast and stay there until they are almost empty , while LiPo has a more linear discharge curve.
If your charge your spare cells after one year, you'll see that they will take a few Ah.
-Olaf

 

[miernik]

18650s are the cheapest A123 B-grade cell now, at 2.05 USD a piece

Wait really? I thought all those ebay a123s were counterfeit.

They are "counterfeit" in the sense that B-grade cells from A123 factories (rejected for being sub-spec) and have no warranty and no A123 logo, are being given a fake A123 logo, that's it. They still come from A123 factories, only came-out sub-spec, so A123 doesn't want to give warranty for them nor sign them with their name.

 

[toolman2]

Well, are we able to get more of these cells or WHAT?

Toolman - no idea yet if they are the genuine article?

yes, the 20ah cell is genuine a123, not fake, or a copy.
but my guess is that they are seconds, the icharger says 2m ohm internal resistance and allthough its not heaps accurate, its the same number i got a year ago from cellmans good a123 cells.
so all in all SO FAR (in the tests ive done, with a few more tomorow) the cells are good but have a bit of self discharge that would be a problem if not used at least monthly.

and to be clear, i bought them from a123rc using the automated "buy it now" thingy here: http://www.a123rc.com/goods-468-Excitingly+Powerful+A+123+PRISMATIC+CELLS.html

- i chose registered or signed with free shipping with paypal and it arrived in OZ in about 6 days.

i would like an email back from them on this, as the concern is that if ordering a good number, then how many are dead from being too flat -this one at 2.38v resting was not far from permanent death, and i would like to ask them what we should do if some in the batch are 0.0v?
if they replace them -no worries.

 

[webfootguy]

Thanks for the update. I might get my cells yet then. I did order a couple of other items and that might be holding up the order.

 

[DOMEPEACE]

18650s are the cheapest A123 B-grade cell now, at 2.05 USD a piece, with the lowest price for 26650 of 7 USD they are 2/3 of the price of 26650 in terms of USD/Wh

Not double weight then 20ah pouches, just 40% more.

18650 have 90% of the energy density of 26650, not a big deal if they are 2/3 of the price!

20Ah pouches are interesting, I actually ordered one, but I've seen their max charge rate being stated as only 1C somewhere, if that is true then I'll rather use 18650 despite the weight, because I can charge them at 4C.

And 18650 are in alu tubes, so I guess are more fire-proof and robust then pouches. And I can't imagine at the moment how would I attach the cable to pouches - paper clips or what?
I bought it as a curiosity, but I think for my van (yes, I plan converting a 2165 kg van to EV) I'd use 18650s anyway.

have fun with that headache!! :lol: :lol: sure 1c takes rediculous power @ 50a+, but these cells will be a hell of alot more stable, reliable, last longer, and lighter! look man, period end the prismatic pouches have the highest energy density in the world right now. as for me cost per Wh/Kg is irrelevant, this is my career if this is your backyard weekend hobby then by all means go with the 18650s, hell even go SLA thats gonna save you max money! there is no point to using lithium in an EV if you are not completely serious about it! performance = li-xx / cheap and effective = sealed lead acid(SLA).

 

[miernik]

but these cells will be a hell of alot more stable, reliable, last longer

How do you know that?

From what I've seen 20Ah pouches can only accept 1C charge, while 18650 can do 4C charge, so at the same charging rate 18650 will last longer, no?

How do you know AMP20 are more reliable and last longer then 18650s?

Which ones do you think will retain more % of its original capacity after doing 3000 charges+discharges (both at 4C)?

Where does your assumption that AMP20 will perform better then 18650?

I somehow had the impression that they are more fragile and will last less then tough 18650 in aluminum cans.
Doesn't less weight come with less reliability usually?

 

[x88x]

am i the only one fighting for marketable EVs?

No. But not everyone has money to burn. Cost most definitely is a factor for most of us.

 

[neptronix]

yes, the 20ah cell is genuine a123, not fake, or a copy.
but my guess is that they are seconds, the icharger says 2m ohm internal resistance and allthough its not heaps accurate, its the same number i got a year ago from cellmans good a123 cells.

I have found that the iCharger is all over the board. It rates my lipos anywhere from 0 to 9mohm. I am sure there is a better way to test this. An amp load / voltage drop test would do as an approximation. How you do on such a small voltage is beyond me though. :/

Thank you for your report thus far. This thread is quite old now and you are the first to report back. I wonder what experiences others have had with these.

 

[maxvdh]

Well, are we able to get more of these cells or WHAT?

Toolman - no idea yet if they are the genuine article?

yes, the 20ah cell is genuine a123, not fake, or a copy.
but my guess is that they are seconds, the icharger says 2m ohm internal resistance and allthough its not heaps accurate, its the same number i got a year ago from cellmans good a123 cells.
so all in all SO FAR (in the tests ive done, with a few more tomorow) the cells are good but have a bit of self discharge that would be a problem if not used at least monthly.

and to be clear, i bought them from a123rc using the automated "buy it now" thingy here: http://www.a123rc.com/goods-468-Excitingly+Powerful+A+123+PRISMATIC+CELLS.html

- i chose registered or signed with free shipping with paypal and it arrived in OZ in about 6 days.

i would like an email back from them on this, as the concern is that if ordering a good number, then how many are dead from being too flat -this one at 2.38v resting was not far from permanent death, and i would like to ask them what we should do if some in the batch are 0.0v?
if they replace them -no worries.

Thanks for the info. What about the mass discrepancy? Didn't A123 specify the mass of these cells to be 480g each and the website says 568 g? If these are good I'd be up for buying 500 or so for myself and anyone else who wants some (no group buy needed).

 

[jimw1960]

From what I've seen 20Ah pouches can only accept 1C charge, while 18650 can do 4C charge, so at the same charging rate 18650 will last longer, no?

Where are you getting that these AMP20 pouch cells can only accept a 1C charge? Anything that can discharge at 30C (600 amps!) must be able to charge at better than 1C, not that a 20-amp charge rate is anything to sneeze at.

 

[Nuts&Volts]

...look man, period end the prismatic pouches have the highest energy density in the world right now....

Sorry to jump in but this is wrong, currently 18650 cells (like those used by Tesla) have the greatest energy density (>200 Wh/kg). The A123 20Ah are about 140 Wh/kg.

By the way thanks for testing these out toolman2, cant wait to see some more data. I might have to jump in the boat buy some of these!

-Kyle

 

[jimw1960]

Aren't 18650 cells are just those little bitty 1.1 Ah cells. At 39 grams, they have an energy density of only about 93 Wh/kg. At 480g, the AMP20 cells work out to 137Wh/kg.

 

[miernik]

From what I've seen 20Ah pouches can only accept 1C charge, while 18650 can do 4C charge, so at the same charging rate 18650 will last longer, no?

Where are you getting that these AMP20 pouch cells can only accept a 1C charge? Anything that can discharge at 30C (600 amps!) must be able to charge at better than 1C, not that a 20-amp charge rate is anything to sneeze at.

Here: http://shop.lipopower.de/A123-Systems-AMP20M1HD-A-20Ah-Folienzelle

Ladestrom (max.): 20A (1C)

 

[Nuts&Volts]

Aren't 18650 cells are just those little bitty 1.1 Ah cells. At 39 grams, they have an energy density of only about 93 Wh/kg. At 480g, the AMP20 cells work out to 137Wh/kg.

Those are old cells. Modern 18650 are 2.3 or 3.3 Ah at something like 45g, the next generation are above 4Ah (with more weight thou). I was talking about polymer chemistry as well (3.7V nominal). I dont mean to change the topic by comparing these cells, I simple wanted to correct the original statement.

 

[oatnet]

Cool, I love working with the prisimatic a123's - great chemistry, easy assembly, great weight and density for LiFePO4. Some healthy competition might drive the price down too!

-JD

 

[webfootguy]

Aren't 18650 cells are just those little bitty 1.1 Ah cells. At 39 grams, they have an energy density of only about 93 Wh/kg. At 480g, the AMP20 cells work out to 137Wh/kg.

The 18650 cells vary all over the map depending on whether they are "power" cells or "energy" cells (the former sacrifice capacity to deliver high power) and the lithium type. The LiFePO4 18650 cells are all around 1100 mAh in this size (and A123 can deliver pretty high discharge rates). The big difference between 18650, 26650, and prismatic cells is the weight of the packaging compared to the weight of active material in the cell. The small format cells have more weight in the case of the battery compared to the larger cells. This affects energy density (Wh per kg or lb) all other factors being equal.

The leading 18650 rechargeable cell (capacity wise) I am aware is is the Panasonic cell. The cells at 2900, 3100, and 4000 mAh have all been mentioned in the press. The reason Tesla can use them (an unsafe chemistry compared to LiFePO4) is that they engineered a pack with multiple layers of safety (cells can short for example without a problem -- just blows a fuse). The cells have safety features built-in such as a PTC device to limit current and a overpressure release valve and an internal fuse that burns out if it overheats. The technical paper on the Tesla pack design goes into some detail on the safety features of the Tesla pack. A good read. They also seem to have more than one supplier for the cells although the only I have seen in the press is Panasonic.

http://green.autoblog.com/2010/04/23/panasonic-delivers-first-3-1ah-lithium-ion-cells-to-tesla/
http://www.greencarcongress.com/2010/01/tesla-panasonic-20100107.html
http://webarchive.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf

 

[webfootguy]

Good news! I just checked and I have a tracking number and a reply saying my order has shipped from Hong Kong. Looks like these cells could be real. Now lets see if they are seconds/B-Grade or not.

 

[stoiko]

THE CELL HAS ARRIVED!
-10 mins ago.
and its genuine!

but, the voltage was 2.38v and that is very unusual..
every one of these cells from cellman etc in the past, have been between 3.34 and 3.35v so i can only hope they have tested this one or something??
maby these are seconds that have high self discharge??
i am charging it now at 10a, it will be done in 2 hours, and i will then get an idea of its capacity, and ill email a123rc with a wtf. :?

capacity report (of charge) and further info due shortly.

Please put real detail pictures of this battery. It`m made in USA or KOREA ?

 

[toolman2]

i can take pics if they were different in any way, but they are EXACTLY the same to look at as all the other pics of them that are everywhere, ive got others from cellman etc so as soon as a unwrapped it, im 100% that its not a fake, they are marked made in korea.

ill check the weight and a bit more load testing tomorrow. but its holding charge pretty good overnight, not a1 but not looking too bad a cell..