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

[deVries]

These are 20Ah per cell at 3.3V, right? So in 7s3p configuration, you'd get 3.3V * 7 = 23.1V for 20Ah * 3 = 60Ah per module? So with three modules connected in parallel you'd get 23.1V, 180Ah or for three modules in series you'd get 69.3V, 60Ah?

We do not know how the wiring or connections specifically work for these modules, so it is pure speculation how to configure these modules for a specific application such as your project. I think you mentioned you are new to electric bikes, so this is a very complicated issue for a newbie to take-on, imo. You'll need to wait until others get these modules AND post the details about these modules. In the meantime keep reading other topics & threads, so you can find answers to the questions you have below. You will have to invest the time to read & learn, since there are already answers to the questions you have below that are ready to be found now on the forum.

Also, most people will charge these cells to 3.6v to get a top-off or surface charge, so you need to take that into consideration to match the proper controller you might use. BUT, this is Off-Topic for this thread, so you'll need to post elsewhere about this.

What is typical voltage and current for a motor sufficient to drive a scooter? (Want to make sure I'm doing the math right...)

Sorry, Off-Topic... Please post this elsewhere. There is a Scooter/Motorcycle section of ES you might want to check-out.

[lukehutch]

What is typical voltage and current for a motor sufficient to drive a scooter? (Want to make sure I'm doing the math right...)

Sorry, Off-Topic... Please post this elsewhere. There is a Scooter/Motorcycle section of ES you might want to check-out.

I don't understand how somebody making a statement about mounting three of these on a scooter is not flagged as off-topic, but me asking a question about how whether that many of these cells would actually work for that purpose is flagged as off-topic, but fair enough.

Thank you for the advice to wait until somebody actually gets the cells before drawing any conclusions.

[deVries]

I don't understand how somebody making a statement about mounting three of these on a scooter is not flagged as off-topic, but me asking a question about how whether that many of these cells would actually work for that purpose is flagged as off-topic, but fair enough.

That post provided useful "estimate" information to this thread: Estimate of Module Dimensions

Check your ES Inbox for a PM. More explanation about what to do next... *IMO*

The topic of the thread you are posting in now is to learn specific information about these modules (construction, specs, cells, pricing, shipping, etc.), and whether we can do a group buy to save money.

(That really has nothing to do with your personal project application speculations or possible unknown or vague scooter build/parts questions... at this point you only have about 5 posts on ES & are just starting out by joining *only* yesterday. lukehutch 10 µW Posts: 5 Joined: Fri Apr 20, 2012 3:59 pm)

Please invest in more reading & learning on ES & post questions in the On-Topic threads or start a new one of your own.

If anyone wants to help lukehutch (click link below), then here is his thread he started yesterday!

Electric conversion of Sachs MadAss

[MitchJi]

Hi,

2. What is the cause?
One of four automated tab welding machines in the prismatic cell manufacturing process at our Livonia, Michigan facility was incorrectly calibrated, causing a misalignment of a certain component in some prismatic cells. This defect was undetected by our standard visual and electrical inspection. 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.

NOTE: "certain component" and "undetected by our standard visual...inspection" sound like something inside the pouches rather than the 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.

Very clever to spot the potential problem but clamping these particular cells could be a big mistake. Definitely need to figure out a way so that in terms of vibration the pouches, tabs and wires/bus bars are rigidly connected.

[Teh Stork]

Yeah, well - that just adds to my confusion at this point. If it was the clamping and misaligning that was the problem - why are we seeing 'new' cells being sold by themselves, not having been assembled or being dissassembled from packs, on the market?

The price is redicolously low. You could buy an extra pack 'just in case' one fails for car building. The balance connector are beefy and everything seems to be high quality.

[Sutho]

Yeah, well - that just adds to my confusion at this point. If it was the clamping and misaligning that was the problem - why are we seeing 'new' cells being sold by themselves, not having been assembled or being dissassembled from packs, on the market?

Because the misalignment fault in the cell only becomes apparent when the cells are compressed into a module.....which they need to be to retain their shape and capacity when operating.

[deVries]

Yeah, well - that just adds to my confusion at this point. If it was the clamping and misaligning that was the problem - why are we seeing 'new' cells being sold by themselves, not having been assembled or being dissassembled from packs, on the market?

My *guess* is that the batch of cells that passed through the misaligned torch did *not* all get made into modules. The potentially defective cells were caught in time before going into the modules, so there is a limited supply of cells too.

Very clever to spot the potential problem but clamping these particular cells could be a big mistake. Definitely need to figure out a way so that in terms of vibration the pouches, tabs and wires/bus bars are rigidly connected.

Agreed. As I posted a couple of times before, my theory is it may be possible to save the *potentially* defective cells by relieving the tensioned bands or the compression pressure that is on the cell stack now inside the modules. Reducing that compression force may actually *prevent* the defective cells from being damaged. IMO. (Of course, doing that may cause other issues that are problematic too.)

I've seen that video of the (heavy-set older) man casting these same stacked cells in a urethane casting. That could be one method to prevent compression loading, yet keep the cell tab areas protected from vibration damage too. Using a lightweight urethane foam or other lightweight resin casting foam of some kind with a mold should work too. Or, perhaps use some lightweight shipping/packing dense foam to encase the cells. Of course, I realize this is not making any good use of the modules if the cells have to be removed or repacked in some way.

It may be possible, though, to relieve the stack compression, and then spray on a foaming agent around the edges of the cells that hardens & maintains the stack integrity. Or, use silicone rubber (or similar) material to make caulking lines/rings for a flexible banding, or use lower tensioned flexible bands like the idea of a bungee cord to keep a lower compression level on the cells.

[Sutho]

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

A slightly more accurate guesstimate on the dimensions would be:

[img]

7s3p60ahTopOff1%20Dimensions.jpg

[/img]

The width and height are dimensions I found in a document. The length is approximated from some known dimensions...

[bigmoose]

Hi,

2. What is the cause?
One of four automated tab welding machines in the prismatic cell manufacturing process at our Livonia, Michigan facility was incorrectly calibrated, causing a misalignment of a certain component in some prismatic cells. This defect was undetected by our standard visual and electrical inspection. 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.

NOTE: "certain component" and "undetected by our standard visual...inspection" sound like something inside the pouches rather than the 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.

Very clever to spot the potential problem but clamping these particular cells could be a big mistake. Definitely need to figure out a way so that in terms of vibration the pouches, tabs and wires/bus bars are rigidly connected.

Mitch you make a good point!

Also putting things together the way you did, makes me opine that a critical piece of additional insulation is missing. As I understand it the foil pouch is perhaps nylon coated. The provides some inherent insulating capability. What if a thin, additional piece of insulation "spacer" insulation is missing/displaced?

Perhaps guys who have crunched cells could very carefully do a destructive physical examination with a scalpel and carefully, perhaps on a discharged cell, taking pictures as they go. Maybe we could piece together what is dislodged, misaligned or missing. It has to be the layer right under the pouch.

[mistercrash]

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

A slightly more accurate guesstimate on the dimensions would be:

[img]

7s3p60ahTopOff1%20Dimensions.jpg

[/img]

The width and height are dimensions I found in a document. The length is approximated from some known dimensions...

I think you are way off on the 240 mm dimension. Dimensions from DoctorBass showed the cells to be 7.25 mm thick, so that times 21 is 152.25 mm. From the pic it looks to me like the plastic parts at either end of the module are almost the thickness of three cells but not quite. To me it adds up to just under 190 mm. Anyway, you'll have the real dimensions soon. Really looking forward on your feedback from the modules you ordered.

[Sutho]

I think you are way off on the 240 mm dimension. Dimensions from DoctorBass showed the cells to be 7.25 mm thick, so that times 21 is 152.25 mm. From the pic it looks to me like the plastic parts at either end of the module are almost the thickness of three cells but not quite. To me it adds up to just under 190 mm. Anyway, you'll have the real dimensions soon. Really looking forward on your feedback from the modules you ordered.

I hope they are shorter.....but I found a document that states that a 22s3p module (66 cells) has a length of 578mm. Did a rough calc from there. There are heat sink plates between each cell and I reckon the end plates, BMS module and packing would probably be about 40mm.

[davec]

your the man sutho
i can't waite to see your review
im curious about
1. cell voltages of all the cells - hopefully all the cells in there are good and you dont get too many bad/ defective ones
2. if it's easy to rip the cells out or reconfigure the pack
3. a cba test on at least 1 good cell to see if it delivers the full specs- and how many AH they can deliver- that will at least give an idea if these are new or used- being in a pack adds more credibility

it'll be interesting to see the results- hopefully their better than the loose ones
cuz the loose ones are truly 16ah cells- sure the guys are cba testing them down to 2volts but once your down below the 2.8 volt mark is quite useless and dosnt have much to offer

[deVries]

This post is just to continue pure speculation & rumor, since we're waiting for modules to arrive in ES member's "electric golden" hands of unobtainium.

BTW, this is opinion, my opinion... I think these modules hitting the grey market shows the desperate financial state of A123. First they dumped loose cells, now they are dumping the modules. All off shore and in China, so (again IMHO) they are free of all legal obligations to ensure these are only sold to "qualified" individuals by US law.

I also think there is some mix of quality in the cells. If I had to guess I would think the cells sold months ago with cut tabs might be the poorest. They were dumped first (perhaps) and neutered by a company that was more healthy. Then they dumped production stockpiles that were aging. These cells may not have had all the QA done on them. So they may have undetected problems. Now I would bet that cells that made it into modules are darn good cells. ...

it'll be interesting to see the results- hopefully their better than the loose ones
cuz the loose ones are truly 16ah cells- sure the guys are cba testing them down to 2volts but once your down below the 2.8 volt mark is quite useless and dosnt have much to offer

Yeah, well - that just adds to my confusion at this point. If it was the clamping and misaligning that was the problem - why are we seeing 'new' cells being sold by themselves, not having been assembled or being dissassembled from packs, on the market?

Another speculation about the sudden availability of unobtainium ...

(At least this guy has ordered over a thousand cells & at least one big A123 module too...)

I don't know how reliable the EVTV guy is, but he keeps rattling on that these cells are not even defective. I think he *only* bases this on his experience buying the loose cells from the same source. He does say WE "here" are at Endless Fear (ES ), though!

He further believes that, overall, battery or 4 wheel e-vehicle sales vaporized & so A123 suppliers or partners in Korea are just unloading perfectly good product. Of course, he provides no explanation about what is going to happen to all the bad or "potentially defective" cells in the meantime that A123 just recently admitted to AND will cost 55 million to replace!

I personally do *not* think this is a coincidence that we can just "now" all of a sudden from out of the blue just start buying what was before "unobtainium"...

[Sutho]

My personal opinion is that A123 have known about the cell alignment problem for a while. As they can't track exactly which cell come from which machine, they don't know which of the cells produced in Livonia are going to exhibit problems. So....best option is to dump the lot and only use known good cells.

If you were A123 and were going to dump the cells, why not get some return in the process and sell them to the Chinese (who have no real morals or recourse when it comes to quality of product) and let them sell them off without A123 even acknowledging that they exist. A123 make some money, the Chinese trading company makes some money....and we get access to product that we had no chance of being able to obtain had their not been a problem with their production.

So.....along with the possibility that the non-US manufacturers of these cells need to maintain production and backdoor cells to keep workers gainfully employed....there are a whole bunch of US manufactured cells and modules that contain up to 25% "dud" cells that have hit the grey market.

I thought that it was a really bad scenario that A123 could:

a) work themselves into a business scenario where they have contracted more production than sales....thus grey market cells

b) produce faulty cells and modules on a super-modern state of the art manufacturing facility built on up to $240M of US Government funding

But.....if this didn't happen, we would not have had the opportunity to purchase these fantastic cells and modules.....albeit with a risk of some failure and loss capacity which can hopefully be repaired without dangerous incident.

So.....some good comes from some bad.

P.s. Length measurement on the 7s3p is apparently 230mm. So I was out by 10mm on my guesstimation.

[mistercrash]

Length measurement on the 7s3p is apparently 230mm. So I was out by 10mm on my guesstimation.

aaaah shoot! I was hoping I was right. Thanks Sutho.

[deVries]

P.s. Length measurement on the 7s3p is apparently 230mm. So I was out by 10mm on my guesstimation.

Thanks. Very good estimate & you only overshot 10mm, not bad.

Since this defect is caused by a torch misalignment, then the root of the defect had to be isolated in that area of the welds at the top of the tabs. The defect can then apparently only occur once the cell stack is in compression inside the modules. So, maybe there is some tensional forces being exerted on the underneath side of the flimsy tabs that are welded to the bus bar above & this is causing some flex, tension, or torsion forces downward into the pouches where the defect can be created or maybe its located back up near the tab area from underneath the welds. I really think just relieving tension on the cell stack may be the trick & treat for a truly magical solution. (I keep repeating myself on this idea in case you haven't read that several times by now. )

While waiting for modules we could further speculate & bet cells about this too...

What could the torch misalignment do to these tabs, because that is the starting point of the problem? This assumes that's the only welding that is done on the cells, right? If so, let the speculation betting begin. Let's deal this hand of 5 card draw with deuces & one eyed jacks wild at least.

Everyone throw one cell into the pot & see who can win this hand. Cheaters will be shocked but A123 inside straights are most welcome!

[John in CR]

My personal opinion is that A123 have known about the cell alignment problem for a while. As they can't track exactly which cell come from which machine, they don't know which of the cells produced in Livonia are going to exhibit problems. So....best option is to dump the lot and only use known good cells.

If you were A123 and were going to dump the cells, why not get some return in the process and sell them to the Chinese (who have no real morals or recourse when it comes to quality of product) and let them sell them off without A123 even acknowledging that they exist. A123 make some money, the Chinese trading company makes some money....and we get access to product that we had no chance of being able to obtain had their not been a problem with their production.

So.....along with the possibility that the non-US manufacturers of these cells need to maintain production and backdoor cells to keep workers gainfully employed....there are a whole bunch of US manufactured cells and modules that contain up to 25% "dud" cells that have hit the grey market.

I thought that it was a really bad scenario that A123 could:

a) work themselves into a business scenario where they have contracted more production than sales....thus grey market cells

b) produce faulty cells and modules on a super-modern state of the art manufacturing facility built on up to $240M of US Government funding

But.....if this didn't happen, we would not have had the opportunity to purchase these fantastic cells and modules.....albeit with a risk of some failure and loss capacity which can hopefully be repaired without dangerous incident.

So.....some good comes from some bad.

P.s. Length measurement on the 7s3p is apparently 230mm. So I was out by 10mm on my guesstimation.

Sutho,

I agree 100%, though I think our odds are better than 75%, since not all cells coming off that machine are bad. Hopefully packs made with only or a majority of cells coming off the bad machine I can't wait for your evaluation of how easy these packs are to disassemble.

The sad part in the A123 saga is that even with the taxpayer money A123 is nowhere close to producing, much less selling, good production run batteries at these prices. Their cells are already old tech, though I haven't seen a match for their power density in a safe form with comparable cycle life. More than anything else, our revolution needs good safe batteries for $200/kwh or less, but then our relatively empty spaces left by cars will quickly evaporate.

John

[docnjoj]

I'll tell you John, even at $200/kw car batteries are still gonna cost about 8 grand to replace. That still makes electric cars expensive, unless these newer cells last 20 years. Anyhoo I just got 14 of the 20ah ones from Xin and they have no obvious defects and all were 3.27-3.28 volts. No lumps or bumps that I can feel either and absolutely straight tabs. Lucky? We will see. I did look carefully at the those new modules and it looks to me like it will be easier to assemble what I want from the individual cells. They don't look that easy to get apart. I could be wrong.
otherDoc

[SlyCayer]

Hey,

By the way, I am in for 8 X 7S3P packs if you decide to do a group buy... from what I had read it's $283.30 USD each?

[deVries]

By the way, I am in for 8 X 7S3P packs if you decide to do a group buy... from what I had read it's $283.30 USD each?

We should know a lot more in the next week or two from now. Yes, that price is correct.

[MN Driver]

no weight or dimension info yet?

Here's the pricing I got:
Price :42.8$ for 1s1p
Price :283.3$ for 7S3P
Price :1600.0$ for 42s3p
Price :1052.3$ for 6S13P
Price :1066.6$ for 28s3p


one 7s3p and a 28s3p would be great for my motorcycle. That'd be 1349.90 for a 35s3p 112V 60Ah 6.7kwh pack (and compatible with my charger, controller and BMS). That's ~$200/kwh, wow.

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

I'm taking guesses that i might not be able to fit a 42s pack where I need and getting 28s packs leaves me out 28 cells if there is an issue leaving me with a workable pack when I jumper around it, I'll buy a spare as a 'just in case'. Looking for close to 100 cells in series.

So 4 of the 28s3p packs would be $4266.44 plus 2 of the 7s3p is $566.60. $4833.04 grand total That would be 98 cells in series with a 28s pack sitting off to the side in the garage. Considering the guys getting these are getting between 18Ah and sometimes a little over 19Ah, I'd have to figure 18Ah when figuring capacity so 98s of 3.2v 54Ah = 17kwh probably. Not bad.
How much could we figure shipping would be?

[deVries]

no weight or dimension info yet?

Here's the pricing I got:
Price :42.8$ for 1s1p
Price :283.3$ for 7S3P
Price :1600.0$ for 42s3p
Price :1052.3$ for 6S13P
Price :1066.6$ for 28s3p

one 7s3p and a 28s3p would be great for my motorcycle. That'd be 1349.90 for a 35s3p 112V 60Ah 6.7kwh pack (and compatible with my charger, controller and BMS). That's ~$200/kwh, wow.

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

I'm taking guesses that i might not be able to fit a 42s pack where I need and getting 28s packs leaves me out 28 cells if there is an issue leaving me with a workable pack when I jumper around it, I'll buy a spare as a 'just in case'. Looking for close to 100 cells in series.

So 4 of the 28s3p packs would be $4266.44 plus 2 of the 7s3p is $566.60. $4833.04 grand total That would be 98 cells in series with a 28s pack sitting off to the side in the garage. Considering the guys getting these are getting between 18Ah and sometimes a little over 19Ah, I'd have to figure 18Ah when figuring capacity so 98s of 3.2v 54Ah = 17kwh probably. Not bad.
How much could we figure shipping would be?

You can email their contact directly about shipping. The EVTV guy said he got the 28s3p pack for $10 per cell, so there might be some wiggle room already on pricing. (Though he has already bought over 1,000 loose cells.)

No one has started the "group buy" yet, because we are waiting for more info about these packs before attempting a group buy. Need feedback here about modules 1st, IMO.

[manywelps]

You can email their contact directly about shipping. The EVTV guy said he got the 28s3p pack for $10 per cell, so there might be some wiggle room already on pricing. (Though he has already bought over 1,000 loose cells.)

Would you happen to have a link?

[deVries]

You can email their contact directly about shipping. The EVTV guy said he got the 28s3p pack for $10 per cell, so there might be some wiggle room already on pricing. (Though he has already bought over 1,000 loose cells.)

Would you happen to have a link?

http://www.victpower.cn/product/552771685-210447990/A123_Scalable_Prismatic_Module_7s3p_.html

email address is somewhere in this thread...

[Sutho]

Based on my experience....don't send any money to Victpower at this point. They don't have modules to ship. I paid my money, they asked me to pay an additional $900 for freight cos' they got the freight cost wrong......then they told me that they want to ship me part of my order and then more when they have more bits.

Will let you know how this pans outs.....