Group Buy? Dr.Bass Steveo found 7s3p Module! Awesome Price!!

[HumboldtRc]

Quotation:283.3$

 Order quantity :2units

Goods weight :36-40KG

Shipping cost :298.4$( need wooden cases as packing ) by DHL (3-5working days arrive US)

Warranty:NEW AND undamaged and voltage test ok

Maybe there is a DOA guarantee, BUT there is a warranty according to your email shown directly above.

Where (what city) was the destination quote given for?


Thank you HumboldtRc for providing that information.

At least they think the defective units are *NOT* a safety issue... from A123 (thanks Mitch! ) ...

"As a result of engineering
analysis and testing, we believe the defect does not create a safety issue. A123 has not received or
discovered any reports of injury or property damage related to this situation. We maintain that our core
Nanophosphate® chemistry and our systems are safe, and this situation is ultimately a packaging issue
for which we have identified the root cause and have taken corrective action."

Btw, if that is the cost to ship to the USA, then the shipping price needs to come down somehow (by Sea or group buy or ?). Otherwise, this company will have to lower the price, imo, IMO.

So connecting the dots we have:
1. Packs that are so difficult to disassemble that its cheaper to sell them for ~30% less than raw cells, in a country with cheap labor.

That is only one *possible* reason among many other reasonable answers. We just do *not* know at this point. For example, 'why' do they state the following on the actual quote:

Warranty:NEW AND undamaged and voltage test ok

We need further clarifications AND LOWER shipping costs -or- lower pricing, IMO.

Northern California.

I'm going to buy 2. They garantee they will check the voltage and make sure the are fine, before shipping.

[deVries]

Well.....I bit the bullet and bought 22 x 7s3p units.

So.....providing the packs don't fail in a dramatic or dangerous fashion, I reckon these are good value. I also think there's a gonna be heaps available...

At least they think the defective units are *NOT* a safety issue... from A123 (thanks Mitch! ) ...

"As a result of engineering
analysis and testing, we believe the defect does not create a safety issue. A123 has not received or
discovered any reports of injury or property damage related to this situation. We maintain that our core
Nanophosphate® chemistry and our systems are safe, and this situation is ultimately a packaging issue
for which we have identified the root cause and have taken corrective action."

Sutho, at least you will not go up in flames according to A123 above!

PLEASE let us know your shipping cost, how shipped, etc. I think you are in OZ but at least it gives others an idea about shipping costs in 22 units.

Thanks again!

[deVries]

I'm going to buy 2. They garantee they will check the voltage and make sure the are fine, before shipping.

Thank you sir.

Do you intend to open-up the module & disassemble (if possible) at least to learn more about it, etc.

Please give us the actual weight & dimensions of the module after receiving, since no one has posted that yet.

Again, thanks!

[Sutho]

Prior to my purchase yesterday I had a lot of correspondence with Xin from Victpower. Although she seems a little reserved with the information, she also seems to be as helpful as she can be. I believe that they sometimes can't provide suitable answers on some questions because they honestly don't know. They come across as just another trading company with the right contacts to get products that others can't.

The terms of the purchase that we agreed on are that the modules must be New, Undamaged and showing Correct Voltage.

Xin would not agree to provide a refund on the modules if they were found to be DOA, faulty or bad (her term).....but she did agree to replace any bad modules with good modules providing I covered the freight component.....which is a damn costly portion.

They provided the following photo which is a new pack and shows no evidence of having been used. No marks on terminals, etc. I believe these are the potentially faulty modules that have not yet been assembled into the larger packs for Fisker and the like. A123 would be dumping them as it would be too risky for them to sell to the contract customers.

Xin said that I would receive 22 brand new modules exactly the same as these.

07s03p 60Ah End.jpg

(99.39 KiB) Downloaded 3 times

The following photo was sent to me by mistake.....but I believe it answers virtually all of the queries in this thread:

This will be obvious to most with any knowledge of the cells or modules, but what this shows to me is:

1. This module was forcibly removed from a larger Fisker pack....hence Fisker identifier label, bent tabs on end of module.

2. Victpower has the "real-deal" from A123.

3. Cell tabs are laser welded to busbars which results in shortened tabs. Thus cells that some have purchased with short tabs were not neutered on purpose, but more likely removed from modules.

4. Removing a group of faulty cells would not be an easy task....but would not be impossible either.

While the above photo initially looked bad to me, with the assurances from Xin, it was the one that pushed me over the line to proceed.

I have been thinking for some time that if I could only get my hands on one A123 module, I would copy it for my own packs as all the engineering is done and the cells are supported and connected as they were designed to be.

Although it is very likely that I will end up with some of the faulty cells in these modules, I believe that repairing them will be much easier than building modules from scratch.

I should receive the modules by the end of next week and provide feedback on their condition, voltages, etc. I will also like to build some form of test rig, so if anyone has suggestions on what this should be, I am all ears.

Cheers,
Sutho

[deVries]

4. Removing a group of faulty cells would not be an easy task....but would not be impossible either.

With a vacuum & dremel blade it looks like you could cut the bus bar between the tabs to remove a bad cell. You would have to cut the two outside bands for the battery pack to remove the bad cell, but, dang, that seems easy-peasy on the face of it. Always easier said than done.

Also, since this is a pressure issue compressing the cells together, causing the defect, heck, it might be possible just to relieve the pack pressure by loosening the bands relieving compression. That might make the "potential" bad cells become good cells like MAGIC.

How much was shipping?

Thank you! Sutho.

[Sutho]

How much was shipping?

Shipping to my location for 22 units was $2500.

[deVries]

...but she did agree to replace any bad modules with good modules providing I covered the freight component...

Considering these are surplus with the certainty there will be some defective cells *UNLESS* my theory of "decompressing" the cell-stack will prevent the defect from ever happening... & it's possible that idea could work & prevent any defects...

Here is why I think this is possible directly from A123:

"When the defective prismatic cells were subsequently compressed as part of the module assembly process, a mechanical interference was created between the misplaced component and the foil pouch which contains the cell. In certain cases, this interference breaches the foil pouch electrical insulation causing an electrical short which can cause premature failure of the battery module or pack, leading to decrease in performance and reduced battery life."

So, decompressing this interface, the cell stack, may *prevent* the defect from ever becoming actually defective in use... just a little less pressure and the potentially "bad" cell survives as a "good" cell. Magic!

Anyway, I think replacing a bad module for free IS much better than no warranty at all. I think you have snagged an awesome deal, *IMO*.

Fantastic!

[deVries]

no weight or dimension info yet?

Just need dimensional information, I won't order them if I can't put to use the modules in my motorcycle.

If you examine the pics posted just above in this thread, then you can see the battery or module size is very near the size of the cells x number of cells stacked in "X" configuration. You might be able to estimate if these will work by using the cell dimensions & making an estimate from that. Obviously, if that estimate is too close to tell, then you'll need to get the exact dimensions. Several have ordered the 7s3p modules, so we will know within a week or so the exact weight & dimensions for that module.

Hope you can get these to fit & work.

[competitions]

There is also a guy in Ireland who uses the online name of "Jack Bauer"- and he has built an EV.

Coincidence? Possibly.

His build thread:
http://www.diyelectriccar.com/forums/sh ... jack+bauer

[deVries]

I should receive the modules by the end of next week and provide feedback on their condition, voltages, etc. I will also like to build some form of test rig, so if anyone has suggestions on what this should be, I am all ears.

Doctorbass, Sir Battman! The Nano Battery Appears in the Night Sky...

Can you help give Sutho some ideas for this?

[Doctorbass]

I should receive the modules by the end of next week and provide feedback on their condition, voltages, etc. I will also like to build some form of test rig, so if anyone has suggestions on what this should be, I am all ears.

Doctorbass, Sir Battman! The Nano Battery Appears in the Night Sky...

Can you help give Sutho some ideas for this?

Sutho ,

This is my suggestion for the test of your cells:

1- Visual inspections on arrival ( physical damage te strange things)
2- If possible put a number on each cell for easy data record.
3- measure voltage of all cells
4- record all voltages of all cells
5- charge all cells to 3.650V at C/2 at normal ambiant temp and cut charging process when current drop to C/20
6- leave the cells sitting for 48 hours
7- measure voltage of all cells ( keep appart the lower cells that have droped by 50mV for severe test or droped by 100mV for economy test
8- record voltage of all cells
9- discharge all cells or cells group (if they are already connected) at 0.5C or 1C and cut the discahrge to 2.0V ( some will say 2.5v)
10- record all measured capacity
11- measure voltage of all cells
12- leave the cells sitting for 48 hours
13- measure voltage of all cells ( keep appart the lower cells that have droped their voltage lower than the average)
14- charge again all cells to 3.650V at C/2 at normal ambiant temp and cut charging process when current drop to C/20
15- leave the cells sitting for 12 hours
16- discharge all cells or cells group (if they are already connected) at 5C or 10C and cut the discharge to 2.0V
17- record all measured capacity
18- compare for all cells their capacity at 0.5 or 1C with the 5 or 10C capacity
19- cells that have have higher diff of capacity between the low and high C rate discharge have a higher internal resistance and should be kept appart.
20- All cells sorted !

Doc



-

[agniusm]

He, he, that looks some job:) I dont think it would be handy to record cell ID's unless u take all apart? Hows the liquid cooling is achieved on these modules? Is it those holes used on the side?

[deVries]

Sutho ,

This is my suggestion for the test of your cells:

1- Visual inspections on arrival ( physical damage te strange things)
2- If possible put a number on each cell for easy data record.
3- measure voltage of all cells
4- record all voltages of all cells
5- charge all cells to 3.650V at C/2 at normal ambiant temp and cut charging process when current drop to C/20
6- leave the cells sitting for 48 hours
7- measure voltage of all cells ( keep appart the lower cells that have droped by 50mV for severe test or droped by 100mV for economy test
8- record voltage of all cells
9- discharge all cells or cells group (if they are already connected) at 0.5C or 1C and cut the discahrge to 2.0V ( some will say 2.5v)
10- record all measured capacity
11- measure voltage of all cells
12- leave the cells sitting for 48 hours
13- measure voltage of all cells ( keep appart the lower cells that have droped their voltage lower than the average)
14- charge again all cells to 3.650V at C/2 at normal ambiant temp and cut charging process when current drop to C/20
15- leave the cells sitting for 12 hours
16- discharge all cells or cells group (if they are already connected) at 5C or 10C and cut the discharge to 2.0V
17- record all measured capacity
18- compare for all cells their capacity at 0.5 or 1C with the 5 or 10C capacity
19- cells that have have higher diff of capacity between the low and high C rate discharge have a higher internal resistance and should be kept appart.
20- All cells sorted !

Doc

Thanks! Doc

What is your opinion of the NASA Bounce-Back test too?

[Sutho]

Hey Doc,

Thanks for the procedure. Will probably initially do that for each module.....as opposed to cell....and will make comparisons between all units and record results.

Cheers,
Sutho

[Sutho]

Hows the liquid cooling is achieved on these modules? Is it those holes used on the side?

The units do not have liquid cooling themselves. They are designed to be mounted on a cold plate which has some form of cooling. The metal plates between each cell or cell-group are heatsinks which lap around the bottom of the cells. The bottom part of these heatsinks are the part that make contact with the cold plate.

There is quite a bit of info about the design and construction of these units available in the web. The following is a quick animated view of how they hang together:

http://www.youtube.com/watch?v=axLnLcH_mmM

There's also this rather large document that's worth a flick through:

A123 Weight and Size Reduction of a Lithium-Ion Battery Pack for an Extended Range Electric.pdf

(3.07 MiB) Downloaded 156 times

[kevo]

Nice reference links Sutho, subscribed

[MitchJi]

Hi,

SO WITH SHIPPING WERE LOOKING AT $20.60 A CELL, 42 cells!

Dan

A saving of about $4.40 per cell. Seems like a bad deal to me if you can't use them as packs.

Anyway, I think replacing a bad module for free IS much better than no warranty at all. I think you have snagged an awesome deal, *IMO*.

Paying $7 per cell in shipping isn't exactly free.

[deVries]

Hi,

SO WITH SHIPPING WERE LOOKING AT $20.60 A CELL, 42 cells!

Dan

A saving of about $4.40 per cell. Seems like a bad deal to me if you can't use them as packs.

Anyway, I think replacing a bad module for free IS much better than no warranty at all. I think you have snagged an awesome deal, *IMO*.

Paying $7 per cell in shipping isn't exactly free.

That's for shipping 2 modules, so a group buy or volume purchase may *possibly* be cheaper. Anyway, no one in China ships anything free to the USA, whether it's new or a replacement. At least the defective module is replaced free of charge, which is a savings of $283. Free shipping does not really exist... shipping is factored in the cost whether it's "free" (not itemized) or not. But coming from China? Get real. Be realistic.

Hopefully, the price will come down further, because there will be too much supply rather than demand. Hopefully, most modules will not be defective, so there will be few returns to deal with anyway. Hopefully!

***EDIT: I changed this to now read: One very positive aspect about these 7s3p modules is it appears these are made in 21 cell rows, so it looks like it might *POSSIBLY* be a simple process to separate these cells using a dremel blade with vacuum. Pure speculation on my part.

[bigmoose]

Note on this picture of the buss bars, that it looks like there are two dissimilar metals, perhaps ultrasonically welded together between the anode triplet and the cathode triplet. Now if you can slice either metal between cells and solder to both, WIN... a big "if" ...

Notice that the cell tap leads are always attached to the buss bar that connects copper tabs.

I also notice what looks like a piece of high density foam between the last cells and the end caps. What I learned from this is that structural loads into the cells (vib, gravity, etc.) is carried through the endplates against the cell faces. They do not carry any loads from the edges or the tabs. Clearly we should clamp these cells into the cases we (who have bare cells) make for them.

[mistercrash]

I don't know much about welding but it looks to me like the difference in color is the cell tabs showing, one is copper and the other aluminum? It's a bit hard to say from the pic but those balance wires look like they are soldered to the bus bars so they might be Nickel. If that's the case then it would be easy to solder to, or together.

Sorry for this question but there seems to be an awful lot of balance wires going to that balance plug, shouldn't there be only 8 balance wires for a 7S pack? Or is there other stuff that I don't know about like temp sensors? Those little blue wires kinda look like exactly that. Or could it be that every single cell is monitored?

[Teh Stork]

One very positive aspect about these 7s3p modules is it appears these are made in three separate 7s strings, so it looks to be very simple to separate these into 7s1p modules by just cutting the parallel connections or wiring connecting the three 7s strings together as 7s3p.

No, judging by the picture - you could not split a 3p module intp 1p module easily. You could certainly easily split them - but saying the result would be a module would be wrong.

I'm seriously concidering buying some modules just to keep for a future project. 3kWh gokart would be fun, the fact that they are already assembled is a plus in my book.

Sea freight from China to USA, or Europe - anyone have experiences?

Ref balance connectors: I think there are two thermal sensors, each connected by the blue wires.

What can we deduce from the picture and thread about the individual cells? I would make a guess around; Width: 7,5mm (cell width)*21 =158mm. Height: ~250mm (Cell with tab are about 250mm). Lenght: 165mm. So we're looking at about 158x250x165 [mm]. Add some padding to make the numbers abit more realistic.

[etard]

Subscribed

[darkone040]

One very positive aspect about these 7s3p modules is it appears these are made in three separate 7s strings, so it looks to be very simple to separate these into 7s1p modules by just cutting the parallel connections or wiring connecting the three 7s strings together as 7s3p.

it looks the opposite to me, it looks like 7 separate 3p strings
so if i wanted a 21s1p battery which would be more ideal for an ebike i would have to flip every middle cell in each group of three then somehow figure out how to connect the nickel plate together.. not as bad of a mess as i thought it would of been..

but if i were to build a motorcycle these packs would be ideal, 60ah would give you a nice range and come in a robust module.. now im rethinking about building an emotorcycle.. hmm

it seems like the extra wires are temp sensors, but that first from the left black wire seems to split in 2 after the heatshrink..

edit: teh stork beat me to it

[Icewrench]

Ooops

[mistercrash]

A guestimate on dimensions of the pack? I could fit three in my scooter. hmm...