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

[HumboldtRc]

How do I resize the photos?

The modules dimensions are 6.5" wide x 9" long x 9.5" tall

I don't own a scale, besides my little one I got from HK, so no weight. The shipping crate said 31kg and I think the cream weighs ~4 pounds, so the modules could weight 14.5kg...?? I'll take them to the a shipping store tomorrow and weigh them.

[oatnet]

How do I resize the photos?
The modules dimensions are 6.5" wide x 9" long x 9.5" tall

The shipping crate said 31kg and I think the cream weighs ~4 pounds, so the modules could weight 14.5kg...?? I'll take them to the a shipping store tomorrow and weigh them.

THANKS FOR THE PICS! I use an ancient application called Thumbs Plus to resize my photos for uploading here - there are a lot of newer applications out there though. Do you have any pictures of the cream module? I have seen a bunch of pics of black modules, but not cream.

For weight, here is what I recorded from the cell_man thread a few years ago...

a123 large format cells
16ah 401g (14.145oz), 7 x 150 x 221mm (0.27559" x 5.90551" x 8.70079")
20ah 467g (16.473oz), 7 x 165 x 227mm (0.27559" x 6.49606" x 8.93701")

So, 3x7=21 bare cells should weigh 9.8kg, or 21.62lbs.

-JD

edit: I forgot I weighed one of the bare cells when I compared them to the cell_man cells - turned out to be 494g/cell from the heavier foil, so 21 bare cells should weigh 10.37kg instead.

Click here to see the comparison

[HumboldtRc]

Both sets of buss bars take solder after you scrape them with a knife.

The funny thing about the battery size is, my pit-bike battery box is 9.5 x 9.5 x 7", which is basically exactly the same size. But I can hold 6s 80ah of HK lipo in it. Compared to 7s 60ah of A123 cells, basically 50% volume difference between them.

[HumboldtRc]

All the cell groups are exactly 3.300 to 3.301.

I will post any new videos or pics, in my new thread.

viewtopic.php?f=14&t=39320

[davec]

I was just about to say - the pack is healthy- how worn it is is another story-
23.11 volts for a 7s3p is good

humbold - for us folks thinking about ripping the cells out of these packs to use as loose cells- does it looks possible?

[HumboldtRc]

No!!! I would not attempt it my self. It would be a huge hassle and waste of time. If you need 20 or 40ah packs, I would be easier to start with bare cells, that still have full tabs. Their is maybe 1/8 of an inch left on the tabs below the welds.

I would just use copper bars to sandwitch 2 cell tabs together and to make a 20ah or a 40ah pack, if that is what you want. Then use polcabonate for the endplates, with 4 bolts in the corners, or some huge band clamps, to simulate the factory A123 modules.

[Pure]

I just got my 2 7s3p A123 modules!

They are clearly used/rejects. The 2 I got are different. One is off-white and one is black. They both read 23.11 volts at the terminals. There is a big dent in the black one, also the heat-sink plates looks thiner on the black one. The white one is not square, it was put together wrong, the whole pack leans.

That's very troubling to hear. If this turns out to be the case for everyone, they won't be getting any of my $ any time soon.

[davec]

HumboldtRc

what about re-configuration? wire the 3 groups in series.. to make it 21s1p?
looking at the picture - i see tons of little wires going to what seems like a BMS
than you got a 3 thic wire- going to what looks like a set of 7s cells....
are these balance wires going to each cell?

[HumboldtRc]

[deVries]

what about re-configuration? wire the 3 groups in series.. to make it 21s1p?

1) +1 Yes, what about rewiring these & ditching the BMS for 21s2p or 21s1p?

2) Is the solder bonding well? In other words, this is not a weak/cold solder bonding? How did you solder it? What iron size & solder type?

3) Search on my dremel idea. Can a cell be cut out using the dremel IF one is willing to cut the bands to open the module to "release" & remove a cell ... then solder in a good cell with regular sized tab by buying some loose cell replacements?

4) Was the dent caused by shipping or was it there to begin with before shipping?

5)

If you need 20 or 40ah packs, I would be easier to start with bare cells, that still have full tabs. Their is maybe 1/8 of an inch left on the tabs below the welds.

If you can use solder to bond to the bus bar, then why do we need to solder to the tabs? Why not just solder to the bus bar after using the dremel to sever/cut the cells/wiring to allow for rewiring & reconfiguration AND ditch the BMS.

Hey, thanks for the video & pics.

[deVries]

The funny thing about the battery size is, my pit-bike battery box is 9.5 x 9.5 x 7", which is basically exactly the same size. But I can hold 6s 80ah of HK lipo in it. Compared to 7s 60ah of A123 cells, basically 50% volume difference between them.

This does *not* make sense to me. Why?

6 x 8 = 48 vs 6 x 7 = 42, so 48 vs 42 is *not* 50% "volume difference".

Also, the A123 module is 1/2" inch smaller than your LiPo package. 6.5" vs 7".

6s x 80Ah x 4.2v (LiPo) = 2016 W

7s x 60Ah x 3.65 (A123) = 1533 W

Only 24% more capacity with your LiPo pack, but volume size difference is even less with that 1/2" module size advantage difference in favor of the A123 pack.

However, IF the A123 cells are good & barely used (less than a 100 cycles), THEN the A123 is a far better deal than LiPo Nano given its TOTALLY UNPROVEN cycle life AND no where near the Quality Control that A123 cells will normally have. Of course, obviously, A123 "fracked-up" a lot of cells recently!

[JRP3]

So you aren't really bottom balancing, you did it once in 3 years. Oh My. I hate to tell you, but large format cells in general, and CALB or Tsky or Sky Energy cells in specific, have great variations in self-discharge rate, which means a few of your cells are likely way out of balance at this point.

Except as I said last time I bottom balanced they didn't really need it. I do check occasionally and they are still in balance. CALB's seem to be pretty consistent.

Anyhow, you have some unusual opinions, and we're taking this thread off topic on a an issue that has been pretty well hashed out on the sphere, so I am not going to reply to posts about bottom balancing in this thread any more, please start a new one (or add to an old one) if you want to discuss it further.

-JD

Sorry for the OT posts, but you started it I'll just end with my "unusual" opinions are supported by information from actual battery researchers. Back to the previously scheduled A123 module discussion.

[JRP3]

I just got my 2 7s3p A123 modules!

They are clearly used/rejects. The 2 I got are different. One is off-white and one is black. They both read 23.11 volts at the terminals. There is a big dent in the black one, also the heat-sink plates looks thiner on the black one. The white one is not square, it was put together wrong, the whole pack leans.

I'd guess whoever removed and shipped these modules to China did so as quickly as possible with little care for their condition. A123/Fisker/etc. consider these to be junk and probably treated them as such, IMO.

[deVries]

I just got my 2 7s3p A123 modules!

They are clearly used/rejects. The 2 I got are different. One is off-white and one is black. They both read 23.11 volts at the terminals. There is a big dent in the black one, also the heat-sink plates looks thiner on the black one. The white one is not square, it was put together wrong, the whole pack leans.

I'd guess whoever removed and shipped these modules to China did so as quickly as possible with little care for their condition. A123/Fisker/etc. consider these to be junk and probably treated them as such, IMO.

Don't forget guys that the 7s3p modules are almost certainly yanked apart FROM the "giant" CAR BATTERY BUILD. Dings, dust, etc. can be expected. Used, yes, but semi-new, IMO, imo. (Rejects, yes, because A123 can *not* use these. )

Also, even IF these cells were cycled 100 times, THEN it's really No Big Deal. Why? The cycle life of A123 is in the thousands IF you care for the battery properly!

[HumboldtRc]

If their not part of the 55m dollar problem, then we should be fine. But most likely, these will have a 75% failure rate, if the bad welding machine messed up every cell it made.

[HumboldtRc]

what about re-configuration? wire the 3 groups in series.. to make it 21s1p?

1) +1 Yes, what about rewiring these & ditching the BMS for 21s2p or 21s1p?

2) Is the solder bonding well? In other words, this is not a weak/cold solder bonding? How did you solder it? What iron size & solder type?

3) Search on my dremel idea. Can a cell be cut out using the dremel IF one is willing to cut the bands to open the module to "release" & remove a cell ... then solder in a good cell with regular sized tab by buying some loose cell replacements?

4) Was the dent caused by shipping or was it there to begin with before shipping?

5)

If you need 20 or 40ah packs, I would be easier to start with bare cells, that still have full tabs. Their is maybe 1/8 of an inch left on the tabs below the welds.

If you can use solder to bond to the bus bar, then why do we need to solder to the tabs? Why not just solder to the bus bar after using the dremel to sever/cut the cells/wiring to allow for rewiring & reconfiguration AND ditch the BMS.

Hey, thanks for the video & pics.

1. Yes it could be possible with a lot of work.

2. The solder bond is perfect. I used a 80watt iron with a hamerhead tip from HK, using 60/40 rosin core, after scraping the spot I was going to solder.

3. Yes it would work.

4. The dent had to be their before they packaged it up. It was shipped in a wood crate with foam around the modules, the crate is in perfect shape.

5. That would work fine. All you would do for the bms is unplug the connector.

[deVries]

I just want to thank HumboldtRC for taking the time to document the modules both in pics & video. It's guys like him that make ES the greatest e-techie place on the net, imo. Thank you, and, of course, thanks for answering my questions below too. I'm very confident now that many could modify these modules based on your answers below.

I hope Sutho will report soon the condition of his 22 modules of 7s3p. That should give us a good opinion of overall "condition" in a large purchase!

what about re-configuration? wire the 3 groups in series.. to make it 21s1p?

1) +1 Yes, what about rewiring these & ditching the BMS for 21s2p or 21s1p?

2) Is the solder bonding well? In other words, this is not a weak/cold solder bonding? How did you solder it? What iron size & solder type?

3) Search on my dremel idea. Can a cell be cut out using the dremel IF one is willing to cut the bands to open the module to "release" & remove a cell ... then solder in a good cell with regular sized tab by buying some loose cell replacements?

4) Was the dent caused by shipping or was it there to begin with before shipping?

5)

If you need 20 or 40ah packs, I would be easier to start with bare cells, that still have full tabs. Their is maybe 1/8 of an inch left on the tabs below the welds.

If you can use solder to bond to the bus bar, then why do we need to solder to the tabs? Why not just solder to the bus bar after using the dremel to sever/cut the cells/wiring to allow for rewiring & reconfiguration AND ditch the BMS.

Hey, thanks for the video & pics.

1. Yes it could be possible with a lot of work.

2. The solder bond is perfect. I used a 80watt iron with a hamerhead tip from HK, using 60/40 rosin core, after scraping the spot I was going to solder.

3. Yes it would work.

4. The dent had to be their before they packaged it up. It was shipped in a wood crate with foam around the modules, the crate is in perfect shape.

5. That would work fine. All you would do for the bms is unplug the connector.

[Sutho]

I hope Sutho will report soon the condition of his 22 modules of 7s3p. That should give us a good opinion of overall "condition" in a large purchase!

Still waiting. My modules would be in the country now....but as there has been some public holidays in China, I haven't been able to get the correct tracking details from Victpower. Hoping to have them by the end of this week.

[zaxxon]

HumboldtRC,

I ordered three of the 28s3p packs last week to replace the small Prius battery pack in our Mini-EV project. Curious to know if the material connecting the cell tabs is all the same? I was speculating that for the Al cell tabs they were using Al, and for Cu Tabs it was Cu. I guessed this because it looks like there is an ultrasonic weld between the different + / - battery terminal group connections. If Al is used we would not be able to solder to those connections directly.

[peterperkins]

I just tried to order 2x 28S3P packs and got the reply they are not selling the modules anymore

Dear:Mr. Peter Perkins

Im sorry , now we dont sell the modules to customer

Coz it exist some questions,even though price is quite cheaper

We got feedback from customers,inside of modules has 2pcs had dead ,1 was shorted

If we sell to you ,when u test after,u will find us to refund

So thats why dont sell now.....sorry ...

If customers dont ask for refund , we will consider..and these modules no any guarantee ,im gotta say

Best Regards

So looks like one or two early buyers are asking for refunds prob via paypal and that is pressuring them. Not great news.

It's not beyond the abilities of this group to fix the modules, so we have to be careful not to cut off our noses to spite our faces with the supplier.
We should perhaps tolerate some degree of cell failure and fix the things. I certainly will be as i have a few spare cells i can solder in.
If we get too demanding the supply will just dry up.

[HumboldtRc]

Wtf!!! I would be so pissed! I still want to buy a bunch more.... Even with no real testing done yet to the ones I have. Hopefully they were talking only about the 28s3p...??

[Sutho]

Wtf!!! I would be so pissed! I still want to buy a bunch more.... Even with no real testing done yet to the ones I have. Hopefully they were talking only about the 28s3p...??

Yes.....what you said!!!

Judging by some correspondence today, I think it may just be the 28s3p at this point. They are awaiting feedback on the 7s3p.....

[deVries]

Wtf!!! I would be so pissed! I still want to buy a bunch more.... Even with no real testing done yet to the ones I have. Hopefully they were talking only about the 28s3p...??

Hey, don't worry, this is a negotiation. It's not like there are a lot of people able to use these modules standing in line.

So looks like one or two early buyers are asking for refunds prob via paypal and that is pressuring them. Not great news.

From what I understand Paypal can't help you on international orders anyway. Only domestic orders protect you w/Paypal. If anyone knows otherwise, then please chime in to correct me.

They can just sell the 28s3p for less money with bad cells too. Maybe $850 or less plus the *real* actual shipping costs.

Anyway, Sutho, did get assurances to get 7s3p replaced FREE (+shipping), IF a module is DOA with bad cells, etc. Soon we will know more about Sutho's bulk order, IF GOOD, then we could ALL JOIN TOGETHER for a group buy. Shipping would have to be split-up between countries, but buying bulk would save everyone $ -hopefully! Yes, here's to hoping!

Shipping by surface sea in bulk would save a lot in shipping costs, IMO, imo, but that's an option worth exploring too for a Group Buy.

[Sutho]

It's not beyond the abilities of this group to fix the modules, so we have to be careful not to cut off our noses to spite our faces with the supplier.
We should perhaps tolerate some degree of cell failure and fix the things. I certainly will be as i have a few spare cells i can solder in.
If we get too demanding the supply will just dry up.

Exactly Peter!

As I stated previously in this thread, I purchased the modules I require + some spares. I expect that they will be new (no sign of damage or use), but I'm prepared to accept that some may fail at some time in the future, and that I will need to swap them out or repair them. That is the risk I am prepared to take to be able to buy these modules at all.

Buyers should not expect this module purchase to be entirely hassle-free. If that was going to be the case, A123 would have kept the modules and we would not have access to them at all....particularly at the price they are (were) selling for.

[EVPowers]

The problem we have is when someone outside forums like ES blindly buys these packs without doing any research.

They expect 100% error free, brand new cells, and as we all know that is not necessarily the case.

Perhaps the price could be lowered even more if we chose to accept them "As Is"?

Oh, and
"We got feedback from customers,inside of modules has 2pcs had dead ,1 was shorted",
sounds like Jack R's pack.