A123 from China. C and avoid [SOLVED]

dear Agnisium,

I am looking forward on how your pack develops, I am in the same situation as you: I am about to get my 34 a123 poch cells and I dont have much of a clue about BMS related stuff and how to install it etc... maybe we can share some pack building experience here :)
 
amberwolf said:
If you want a cell-level HVC/LVC monitoring, without all the balancing and stuff, Methods has one you can build into the packs themselves, becuase it uses so little power (especially compared to any other monitoring system I'm aware of).

Currently it's setup for RC LiPo/LiCo levels, so you'd need a version made with different voltage cutoff points. AFAIK that simply requires installing different chips; his thread in the Online Market has a link to the technical development thread. Would be easy enough to build your own based on the design and chip choices, if you pick the chips that correspond to your LVC and HVC.

If there were enough people that needed them for LiFePO4 stuff, Methods would probably make a batch of them (but it might have to be a LOT of units needed).
Click to expand...


Thanks. I would actually need the balancing function. There is no use for monitoring function only in my case. I need reliable solution to just plug the battery pack for charging and then comeback whenever i want, disconnect and use the bike. I dont like the idea of sitting around hours and waiting till the buzzer will come on. I mean there are solutions for that, i just need to pick a best for the buck.

spkpn said:
dear Agnisium,

I am looking forward on how your pack develops, I am in the same situation as you: I am about to get my 34 a123 poch cells and I dont have much of a clue about BMS related stuff and how to install it etc... maybe we can share some pack building experience here
Click to expand...

I hope that people will kindly share some thoughts on the BMS and guide us the right direction. I am not that concerned in connecting it as getting the right stuff that will keep the pack juicy and healthy.

EDIT:
My battery pack will be set up this way: 4 stacks, 6 cells each:
IMG_20111219_161554.jpg
 
I know at one time they offered to have some readily available or at least mostly finish, at a price of course. But as far as putting one together, as long as you can follow instructions it shouldn't be that hard, and Garry is always there to help.
 
I made this cargo bike with 16s Thunderskys in the bed. Worked very well as a battery compartment. I mounted the controller on the "steering column".

IMG_0276.jpg

IMG_0136.jpg

IMG_0135.jpg

Larry Barefield
 
agniusm said:
It looks like a lot of work gone in making that BMS. The only down side is you have to assemble it your self which for me would go wrong somewhere along the line.
Click to expand...

You can try 2 of this. http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2011-4Q-MW2C.1NESK
I am using 2 of them but LiIo version. Very simple analog operation no microprocessor to go nuts. You will need 2 diodes as well, 1 in parallel to every BMS to prevent reverse polarity.
 
liveforphysics said:
toolman2 said:
liveforphysics said:
Was that 20Ah pouch that says "made in USA" included in your shipment?

Because those pouches are exclusively made in Korea. No USA A123 pouch cell mfg exists.
Click to expand...

ive had heaps of them that say USA as well as Korea, and they ALL have over 19.5ah and can output 300a+ (around 1m ohm, and all seeming pretty dam genuine)
come to think of it in over $5000 worth of these cells, ive only had one that was a bit low in volts on arrival (had self discharge) but now even it came good, so 100% success rate even from some shady Chinese vendors. your out of luck man, just double check the volts, and try charging one..
Click to expand...


If you get a counterfit cell that performs well, and they are consistant and matched well enough to make a pack from, then by all means, run the piss out of them and love it. I think there were some counterfit 26650 M1 cells tested on RC groups that had more capacity and lower resistance (making them better performers for power and energy density) than genuine A123 cells.
Click to expand...

I just pulled 48Amps out of a 12s 1p string of the A123 18650's I got off ebay. They were 12 cells I had shorted, damaged, or deemed otherwise unfit for any build.

48 Amps, left a black smudge on the garage floor where I held the 24v rated Ananda/Cute geared motor down while pumping the throttle.

Cycle-Analyst DP used to measure it.

My only remaining issue is this: could cells with a 1, 2, or 3c rating perform that well, or must the cells have 30c/60c pulse abilities?? In other words, is it normal to be able to get once-off high discharges, from 1c or 2c cells, after which the cells are junked?
 
amberwolf said:
You can get high currents from most kinds of batteries, but their voltage will drop based on their Ri, which in the case of lower-C-rate cells will be higher than that of high-C-rate cells (sometimes by quite a lot).

Also because of that higher Ri, they'll heat up faster, and in the case of some might get so hot that the electrolyte vaporizes/boils, either puffing a pouch cell (or rupturing it's seals), and potentially blowing apart a too-well-sealed cylindrical cell (most are not sealed well enough for that to happen, but soldering cells together could seal the vent, depending on how they're made).


As to whether it makes them discards after doing it; depends on the cells. If they get that hot, enough to puff or vent, yeah, I'd say so. :) But otherwise, it's likely they simply have shortened lifespans--by how much, I have no idea.
Click to expand...

Hi thanks for your reply, Happy New Year.

Can a 1c 1000mAh cell really be discharged at 20A or more?

I used to own a Cammy 20Ah duct-tape battery and the most amps i ever got from it was 25 or so, and the entire bike would be vibrating like hell until the motor came up to speed.
 
I have tested replacement cells from victpower. 2 cels was 18.4 and 18.71, 8 cells above 20AH, the rest not less than 19.38, tipicaly 19.7. Happy with the results. will be starting on battery pack.
 
agniusm said:
I have tested replacement cells from victpower. 2 cels was 18.4 and 18.71, 8 cells above 20AH, the rest not less than 19.38, tipicaly 19.7. Happy with the results. will be starting on battery pack.
Click to expand...

Very cool...what was the website you bought these from?
 
I dont think you read the whole thing. I wasn't insulting any one except someone who blaming me for not testing them properly and after my friend tested them not taking it into account. This all thread is about experience dealing with exact company.
Besides this i got replacement cells after i have opened paypal claim, and supplier shipped new cells with no additional charge. Keep in mind that i would need to pay double import taxes and double postage in normal circumstances, that is ship bad cells to supplier and pay taxes for the replacement ones in most cases or i would loose a lot of time dealing with customs for a refund. There is a fact that there are a lot of doggy suppliers in China which may lead on loosing your money in the end.
I think someone is more of a D...ck, coming and barking nonsense without reading all the posts and making assumptions on hes/her stupid thoughts.
This is not a guide, it is some info from my experience and outcome dealing with victpower China for someone to take into account if buying from them.
 
anonymous coward said:
(and yes, I created an account JUST to point out how much of a dick the OP was over the course of these 10 pages, spitting on people that were trying to help despite this being a simple "fact of life" issue where sometimes modern technology gets shipped as duds)
Click to expand...

Ah yes, the finer elements of ES. Classic. Your other posting ID in this thread stated the same. :!: jmho.
 
Thanks for showing the difference between counterfeit and the real thing, but to be honest, most around here looking to risk buying A123s are primarily looking at the 20Ah pouches. I mean if you are to take a risk in ordering from china, these make for a better risk assessment. Not to mention cylindrical cells are a pita to build larger packs from. So much more difficult, it just makes more sense to purchase ready made packs from cellman, not to mention he will work with for special shapes and designs of the pack for your needs.
 
I just found vpower.hk selling original A123 26650 http://vpower.hk/product.php?id=62
 
i've just got some a123 20ahr korean made from chinese supplier, ahr from 16 to 20ahr
looks good
 
I'm assuming c rate is 0.5c or 10amp is correct discharge to get ahr?
 
I think this is quite exciting, via taobao you can pick up these cells for under $9usd, in the last few months there are numerous sellers popped up, looks like there is a flood of these cells out there, finding the source of these cells, they would be dirt cheap,
my guess they might have been used in china either for power supplies or evs on a quite large scale...very exciting.
 
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