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

[bigmoose]

Dave please present your proof that the loose cells are "krap"... Until folks get these modules and disassemble, we don't even know the usable tab length after you cut them free from the bussbars. Clearly 60AHr is too large for a bike or Trike...

Please present your test data or links to sources that did test them... We, as a community, are in an attempt to discern where the defective cells are, and at what percentage.

[peterperkins]

I'm curious about the bus bars.

They are laser welded onto the tops of the tabs as far as we know.
But what are they made of?
Are they two different metals on each side to fuse with the copper or aluminium tabs?
Joined somehow along that dotted line between 3 pos and 3 neg tabs? Or is that some sort of fusible link?

Anyhow if we assume the bus bars are one type of metal then using a dremel to seperate cells cutting exactly in the middle of the spaces between cells but leaving the laser welded part on the tab it would seem a trival job then to overlap the part and flow solder onto the bus bar metal rather than the tab itself.

If that makes sense.

[Harold in CR]

Makes sense to me. That is exactly how I figured to cut cells loose and reattach to leads.

Just waiting for someone to get one and open er up.

[miro13car]

dave,
bigmoose's thread is reposted here by Devries,
bigmoose did not post here his thread with pictures above.

[davec]

regardless- who posted what- he was only making a reference - i'm not going to argue over loose cells on here- we should keep this a module thread for folks curious about the 7s3p packs- cheers

[deVries]

i'm not going to argue over loose cells on here- we should keep this a module thread for folks curious about the 7s3p packs- cheers

I agree we should not *argue* over the loose cells, BUT the loose cells make modules. The *source* of the defect is some type of misalignment involving the "torch" (laser) AND the cell. It is perfectly reasonable to speculate on this thread with the kind of quality post, i.e. excellent observations & documentation, that BigMoose made (that I re-posted here from another thread).

BigMoose found two different cell anomalies that may be directly or indirectly related to the defect. It is very helpful to have that informative knowledge posted on this thread for reference purposes & it is definitely "On Topic".

Anyhow if we assume the bus bars are one type of metal then using a dremel to seperate cells cutting exactly in the middle of the spaces between cells but leaving the laser welded part on the tab it would seem a trival job then to overlap the part and flow solder onto the bus bar metal rather than the tab itself.

If that makes sense.

Yes, it makes sense to me too. I've posted this same idea 2-3 times in this thread too, search on dremel if interested, so I'm hoping this is correct. Here's to hoping! Someone will explore this possibility once the modules are in our devious (KFC black & scarred) hands.

[bigmoose]

You gents will know soon enough. ... but I have been speculating from the photographs. I opine that the "buss bars" may be two different materials ultrasonically welded where we see the crimple zone about halfway down, or between 3 cell stacks.

Next it looks like the clearance through the black plastic "cap" is small. So one may not be able to extricate a cell by dremelling off only one side of the "bus bar". That slit in the plastic cap or header may only allow the cell tab through. If that is the case, then the tabs might be too short to reuse in this great and nifty packaging, and an alternate cap may need to be fabricated to do the interconnects for 1PxS.

The A123 packaging design looks really nifty. I sure hope it can be reconfigured.

[liveforphysics]

Just having a 60Ah pack is not too bad of a thing either.

A pair of these modules in series to make a 60Ah 14s pack would be a pretty nice ebike setup. It's going to hold about 45v for you until the cows come home, and that's enough voltage to make a mean bike if you just use a higher kV motor and don't mind needing a little larger wires.

[Kirk]

Clearly 60AHr is too large for a bike or Trike...

I've never had the chance to do anything with A123 cells but my tike does just fine with 64 Ah of Zippy Lipo at a bit over 50 lbs. Why would 60 Ah of A123 be too large?

[deVries]

Just having a 60Ah pack is not too bad of a thing either.

A pair of these modules in series to make a 60Ah 14s pack would be a pretty nice ebike setup. It's going to hold about 45v for you until the cows come home, and that's enough voltage to make a mean bike if you just use a higher kV motor and don't mind needing a little larger wires.

+1

Hey, Luke, has had (or maybe still does) have a crap-load of LiPo Ahrs on his commuter bike. What was it Luke?

I think it was somewhere between 40-60Ah at some point along the way of Luke's build. Maybe Luke can tell us what his higher capacity setup was?

A 48v 42 cell pack in 14s3p 60Ah is going to weigh in at about 44-lbs just for the cells, so this 60Ah setup is obviously *not* for some high performance maneuvering bicycle or trail bike unless we bump-up to trials, motorcycle, or dirt-moped format. But a commuter bicycle with long-range AND less need to charge very often is definitely doable. Luke has mentioned the benefits of having a high-capacity setup to extend battery life *and* not have to balance often (if at all), because you don't have to drop the pack down to lower levels before charging again with that extra high-capacity on tap.

EDIT: Luke's Commuter Bike has or had: 25S (100v+) 25Ah of Nano's ... Sooo, covert that to 50v and the Ah goes to 50Ah. Btw, Luke's Commuter Bike is a Race Bike too!

[texaspyro]

Some very good advice in here, but I have one question: how do I know what the market price is to begin with?

Mavizen says the market price is X. Some unknown Chinese person on Alibaba says it is Y. Then somebody here says it is Z.

Thanks.

It's "Q".

[texaspyro]

The last time somebody sent me something significant (around $10K) via DHL, they wanted certified copies of my birth certificate, social security card, and and the last two years of my income tax returns before they would deliver it because of alleged Homoland Insecurity rules. I told them that they cold go fornicate an aids infested hedge hog, and to return the package to the sender in London. He then re-sent it to me Royal Mail. It arrived two days later, I didn't even have to sign for it. No more DHL for me...

[SlyCayer]

The last time somebody sent me something significant (around $10K) via DHL, they wanted certified copies of my birth certificate, social security card, and and the last two years of my income tax returns before they would deliver it because of alleged Homoland Insecurity rules. I told them that they cold go fornicate an aids infested hedge hog, and to return the package to the sender in London. He then re-sent it to me Royal Mail. It arrived two days later, I didn't even have to sign for it. No more DHL for me...

Same happened to me, not that much value, but I was shipping to one of our customers in NZ and the wanted to use his DHL account, so we did, and they asked the guy basically every thing that had to do with his business, so he said no, did the same has for you, sent it by UPS and voila, it got delivered without a problem...

DHL has quit on Domestic shipping within the U.S. because they can't provide customer service, I have learned why.

[cwah]

Anyone knows the total weight of an 7s3p module? I know the cell are 0.480g. So a 21 cell module weight at least 10 kg.

But added as a module is it much heavier?

[deVries]

Anyone knows the total weight of an 7s3p module? I know the cell are 0.480g. So a 21 cell module weight at least 10 kg.

But added as a module is it much heavier?

Check back next week about Wednesday on this thread. I think we will know around that time frame next week.

[silentflight]

FYI guys,

Jack Rickard discusses the A123 module he ordered from China in this week's video starting at 24' 25"

http://www.evtv.me/vidarch.html

[cwah]

Anyone knows the total weight of an 7s3p module? I know the cell are 0.480g. So a 21 cell module weight at least 10 kg.

But added as a module is it much heavier?

Check back next week about Wednesday on this thread. I think we will know around that time frame next week.

Ok going to wait then.

Looking forward for the results

[Pure]

Just having a 60Ah pack is not too bad of a thing either.

A pair of these modules in series to make a 60Ah 14s pack would be a pretty nice ebike setup. It's going to hold about 45v for you until the cows come home, and that's enough voltage to make a mean bike if you just use a higher kV motor and don't mind needing a little larger wires.

I'm watching this thread with great enthusiasm for this very reason. 3 of these would be perfect for my trike build. Mounting 2 on each side of the frame under my seat and one in the cargo platform behind my seat, the extra weight shouldn't really be noticeable. It's all about how and where you mount them. 72V 60Ah A123 goodness for less than a grand...*drools*

[davec]

silentflight - good find - very informative

that video certainly answers most of my questions - he claimed the module was used and had some bad cells in it - rebuilding/fixing these seems extremely difficult so i can understand why he gave up it's simply not worth it. Although Jack did a good review he could have still done a 1c test for us so we can see the specs on at least 1 cell. He made it clear why their dumping these on us- my personal guess is they might be coming out of used sources due to cells getting bad in them. how worn are they would be my next concern- and my last concern is the possibility to tear cells out to build a custom pack and how much tab is left after cutting them loose- and what's the process to do that.

the positive is that the cells are coming out of a legitimate factory built pack.

My only intention of getting one of these is to rip it apart take the cells discard the bad ones and build my custom pack.... i wonder if it's possible and how much effort that will involve... hopefully someone will have an answer when they get it on Wed...

[mistercrash]

FYI guys,

Jack Rickard discusses the A123 module he ordered from China in this week's video starting at 24' 25"

http://www.evtv.me/vidarch.html

I just finished watching the segment. Thanks for the link SilentFlight. For anyone interested, and for anyone who don't have the time to watch and still would like to know. After some testing, Mr Rickard is not too impressed by the 28S3P he got. First he was not pleased with the shipping and Paypal fees he paid which he said were more than the pack itself. Well a reason for this might be, like some think in this thread, that he was not successful negotiating with the vendor. I can't remember if it was said in here that the modules were new, the one he got definitely was not from what he reported. His opinion on the physical aspect of the pack is that it's over engineered and under built. The pack is very compact and very light compared to other alternatives to have the same kind of power. He reported the pack weighing 106 pounds. No words on exact dimensions.
When trying to do his "bottom balancing" technique, two cells were lower than the others. He managed to bring the voltage up on one but the second one went dead.
He tried to take the pack apart, probably to see if he could replace the dead cell. The straps that hold all the cells, heat sinks and end caps together are Stainless Steel which are spot welded, easy to take apart but difficult to put back on, the bus bars are welded to the cell tabs and DO NOT take solder, he wasn't able to TIG weld either to the bus bars.
He came to the conclusion that once a cell goes bad, the whole pack is trash since he feels it is not easily serviceable. For now his conclusion is that he doesn't want to keep tinkering with the pack and he doesn't wish to get a second one.
Not my opinions here, just reporting Mr. Rickard's view from what I can remember from the video. I found it interesting to watch as it answered a couple questions asked in here about the modules.

[kevo]

Mistercrash,
Thank you for the summary on the video. The load times for the evtv were excessive. Disappointed to hear how difficult it was for Mr. Rickard to take apart the packs. Hope ES members are able to find alternative ways to reconfigure cells

[JRP3]

I wish Jack had dug a little deeper, but I'm sure the people here will. If he had dremeled off the weld on the tabs to see how much tab was left to work with it would have been informative. I'd think you could figure a way to clamp in a new cell to the existing bus bar. The band doesn't seem like big deal, just drill out the weld.

[kevo]

JRP3 wrote: I'd think you could figure a way to clamp in a new cell to the existing bus bar.

Not ideal, but I suppose given the moderate weight (for ebikes anyway) could be an option. I'm waging (at least hoping) once units arrive people will step up to the task.

[mistercrash]

I wish Jack had dug a little deeper, but I'm sure the people here will.

Exactly what I thought when I watched the video. Many in here don't give up so easily.

Edit: I want to make clear that I'm not insinuating that Mr. Rickard is a quitter. From what I've seen from his videos, I didn't watch all of them, he has been tinkering for quite some time with A123 cells lately and I feel he just didn't want to waste any more of his time with this module he got.

[deVries]

The 28s3p "bare" module weight *not* counting the cells is just under 18-lbs.
Cell weight is just below 89-lbs. 84 cells x 480g.
Total module weight is 106-lbs. EDIT: 106-lbs is only referenced verbally on video from Jack Rickard's 28s3p module. So, all numbers depend on the accuracy of his measurement. The weights below should *not* be on the low-side or underestimated, imo, so actual weights may be very slightly less than what is predicted below.

7s3p packs are therefore going to weigh about 1/4 the above numbers:

The 7s3p "bare" module weight *not* counting the cells is just under 4.5-lbs for module only.

21 cells add about 22.5 lbs, so total weight for a 7s3p module will be about 27-lbs or slightly less.