How much is getting tested & matched A123 20ah cells worth?

[John in CR]

I'm developing a new relationship with a battery vendor / pack builder in China. He seems quite knowledgeable with respect to batteries and does pack assembly. While making arrangements for some test packs I inquired whether he had a source for the 20ah A123 cells. He hasn't dealt in them before, but found a source, so we arranged to get 4 to test and make sure they weren't junk. He picked them up and all had right around 19.5ah capacity at a 10A discharge rate, and an IR of less than 1mOhm, so they seem to be the real deal.

He quoted me a price of $24/cell plus $2.50/ea for capacity and IR testing (plus shipping of course), so it's possible to get tested and matched cells shipped directly to each buyer. Since self discharge is important he suggested charging them and waiting a week to do the capacity discharge measurement, so we're testing for self discharge too. I'm trying to gauge interest, since a volume greater than I want should net a cheaper price, and the more cells in total, the better the matching of the cells each will get.

This is a new supplier for me, so we shouldn't go hog wild with initial orders. I did surprise him with a request for a reference, and he gave me FalconEV, which I verified. It wasn't a preplanned deal as my reference inquiry was a surprise to the gentleman at Falcon, and my guy in China had supplied them with some battery packs without issue.

I want to first get a handle on interest, since we don't know how quickly the A123 supply will dry up. Once we see how many then I'll talk to him and put those with real interest in direct contact. Separately I'm getting some 4C and 20C NMC's in custom alignments from him for testing, and if those test well I'll turn you guys loose on those too in hope that the volume I help create nets us all a cheaper and reliable source for batteries. I don't want to flood him with all the same questions from a bunch of different people all at once, so let's get questions answered first, and then put those who are serious in direct contact.

John

[gensem]

Awesome, aside from motor and a frame you are going to provide us battery too!
NMC testing...

[arkmundi]

Yea, I'd be interested in the real deal, fully capacity checked, before they get bought and shipped. Sounds like a way to move forward on the supply. I'd take 12 of them - a 12S1P pack, at that price, if they indeed were genuine, full capacity and no sign of self-discharge (they hold). That's about the price from Victpower after bad cells in a carton are discarded. Thanks.

[agniusm]

This is great news. I just got the price from ONSpower and it was 28USD per cell unknown capacity or state. This brings us to 26.50 tested.
About A123 drying up, i think no one will let proven good technology go to waist after so much investment and someone will make it happen give time.
Thanks John

[John in CR]

Awesome, aside from motor and a frame you are going to provide us battery too!
NMC testing...

Call it facilitating instead of providing. If the 20C NMC's work out then yes packs to fit the frames, and/or 4C's for which the batteries are an integral part of ebike frames for super stealth and big capacity, like 28 or 38ah up to 74V in down and top tubes 3.5" in diameter for 28ah and just over 4" in diameter for 38ah.

For the A123's hopefully it works out as essentially ongoing group buys with the lead guy in the battery business and local to the batteries saving a layer of shipping, and which hopefully avoids duds or at least has good potential for exchange at little or no cost.

John

[arkmundi]

For the A123's hopefully it works out as essentially ongoing group buys with the lead guy in the battery business and local to the batteries saving a layer of shipping, and which hopefully avoids duds or at least has good potential for exchange at little or no cost. John

Sounds good, exactly what I had hoped to achieve with my group buy offer, but better. Anyway, how will you notify us if you're going forward? Can you PM me? Thanks.

[John in CR]

For the A123's hopefully it works out as essentially ongoing group buys with the lead guy in the battery business and local to the batteries saving a layer of shipping, and which hopefully avoids duds or at least has good potential for exchange at little or no cost. John

Sounds good, exactly what I had hoped to achieve with my group buy offer, but better. Anyway, how will you notify us if you're going forward? Can you PM me? Thanks.

Let's call it 2-3 weeks. He's got some assemblies to do before my initial order ships. In the meantime, we'll gather up questions and get answers get an idea of participation. I get my stuff in hand including that handful of A123's, so I get the warm fuzzies before I commit more money for what I want, and feel comfortable in referring you guys to him and ordering more for myself. I'm at my exposure limit of $1k only $100 of which is the A123's, and after getting burned in the spring on batteries I'm not letting batteries cloud my judgment.

[999zip999]

After talking to victpower the short tabs with one cheese grater tab are 21.50 shipped for 50 cells. I just hate looking at that swiss cheese tab. And these are 2nd hand. I would love to wait and see. I'm in for 25 cells. I don't want a hobby battery I want build and stay build.
What flavor are the NMC cells 800 or the 2000 cycle ones 20c of course. But true 4c is great. O.k. stettle down. What is a man to do. Thanks JohnCR

[cwah]

I'm interested on the NMC 4C. What's the gravimetric density?

There is 1 thing he can't test: The shelf life! Too sad

[J Barrie Wilkinson]

I would definitely be interested in 16 pouches/cells. You mentioned that your supplier is a vendor/pack builder, perhaps it is is possible that he may supply assembled packs.
Thank you for all your efforts John.

[gensem]

I sooo want a 22s 20c NMC pack!

[liveforphysics]

JohnInCR is an excellent seller and a guy I would trust my life and money with in a heartbeat with no hesitation. I've had the huge pleasure of visiting him in beautiful Costa Rica and got to know him pretty well, you don't have to worry about him pulling a scam/stunt to take our money.

I think he is approaching this the right way (cautiously). Let a package arrive with some cells in it, test them and see what you're working with and make sure the supplier is legit. Test the stuff and see what you're working with. Then perhaps test the guy again with a little larger order.

With respect to the NMC cells, the for sure the best cells in the world right now use NMC, but that doesn't mean because it's NMC it will be amazing automatically. The chemistry alone determines maybe <30% of a cells characteristics (safety, cycle-life, calendar life, C-rate, etc). The other 70% of how that cell is going to perform is up to folks designing the cell (a very big factor simply being the quality of the solvent used). What I'm saying is, you can have some really doggy NMC cells with crap life and bad sag and crap, OR, you can have amazing NMC cells with crazy energy density and 10,000cycles and awesome safety etc. Hopefully these are leaning more towards awesome than sketchy, but don't automatically assume just because it's NMC based that it's automatically going to kick-ass until you test them.

[gensem]

Luke im really hoping that 20c NMC John is about to test is in the same league of the major players, like LG, EIG, etc

[John in CR]

Thanks Luke, and based on the pricing I'm looking at, I'm hoping these NMC's are at least middle of the road, because I'm sure they're not top shelf. If I knew where we could get the best cells I'd be all over it. If these 20C cells are a safe but comparable alternative to 20C RC Lipo, then I'll be happy. At a minimum I'll have some real fun hammering on them for as many cycles as I can in as short a time as possible.

[flathill]

Anyone tried this prismatic
http://www.batteryspace.com/New-generat ... -10Ah.aspx

I have a bunch of the 26650 nmc cells from them and have been happy so far
Cheaper than the 10ah prismatic and rated 1500 cycles
But lower energy density (steel can)
Built three 8s2p packs
All test to rated capacity
Most importantly none showed high self discharge after a month of sitting fully charged
And all showed equal bounch back after discharge and sitting a week

No case needed just solder tabs and hot glue (low tech phase change cooling) and kapton tape wrap
Also picked them up so no shipping for me and cash price
Still expensive but at least im supporting a local supplier who will exchange dud cells

From what ive seen they usually underrate cell life on their own spec sheet compared to the oem spec sheet to be conservative
You never see that

Not cutting edge but it should be safer than hobby lipo if even for the build quality

[etriker]

How much is getting tested & matched A123 20ah cells worth?

A lot I would think. Most of the work in building a pack is testing and matching the cells.

Then again I would still need to test and match them because,,, well I just would.

Shhhhhhh, (keep the best ones for me and sell ya'll the rest)

[t3sla]

$2.50 a cell for testing/matching is really worth it.
It's like a 12% tax that ensure QC

[toolman2]

yep, $2.50 a cell is nothing so go for it.

but i can say after seeing around $5000 worth of these cells in action, some from the very first lot years ago from cellman and used daily, they were all between 1-1.6m ohlm and 19.2-20.1ah -every single one was good for me.

and john the self discharge is also about the only issue i noticed initially too, and im happy to report that the 3 cells that were this way, one of them arrived at 1.3v and ALLWAYS seemed to drop to 3.4 within an hour of 3.6v top off (instead of 3.55 that others would hold for 24 hours) -the problem has faded away after heaps of cycles, and i dont notice it anymore.

but the lower ah cells are limiting my pack to their min and it seems they get beaten up more, and those that were low in ah (and the all kept their original positions within the group) are now about double the gap to the the best ones that never suffer the lowest volts.

so it seems to me like capacity matching will hold pack goodness way longer as the gaps grow years later, so good plan.

[John in CR]

Since these tabs aren't so easy to connect, who else wants the tabs welded? Should I ask about balance taps too, or is that easy? I haven't paid attention to pack building with these cells, since I don't have any. I hesitate asking for ready to go packs. Welding tabs is cheap and easy for a pack builder, so that should be cheap.

He told me that supply varies but is ongoing, but I don't know how the recent A123 news affects it, especially those made in Korea, since both are available at different times.

John

[999zip999]

I used the drutledge compession tab build it should br fine for an ebike. Would like to know how many amps it's good for. Plus you can replace a cell. Maybe not your monster cycle snuff.

[Arlo1]

Hey John what happend in the spring that a battery "burned" you?

[John in CR]

Hey John what happend in the spring that a battery "burned" you?

Sangesf group buy.

[Arlo1]

Hey John what happend in the spring that a battery "burned" you?

Sangesf group buy.

You get your money back?

[arkmundi]

Since these tabs aren't so easy to connect, who else wants the tabs welded? Should I ask about balance taps too, or is that easy? I haven't paid attention to pack building with these cells, since I don't have any. I hesitate asking for ready to go packs. Welding tabs is cheap and easy for a pack builder, so that should be cheap. John

No, I want to easily replace cells, so no welding. Thanks.

[etriker]

Since these tabs aren't so easy to connect, who else wants the tabs welded? Should I ask about balance taps too, or is that easy? I haven't paid attention to pack building with these cells, since I don't have any. I hesitate asking for ready to go packs. Welding tabs is cheap and easy for a pack builder, so that should be cheap. John

No, I want to easily replace cells, so no welding. Thanks.

Right ?

If they are easy to replace then you can just put them together, balance charge them then take em for a ride and see right away which cell runs out first.

That is the best testing !