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

[bigmoose]

A123 is also a big player in grid storage, I wonder if these packs may be swap-er-oos for a power company customer.

I wonder if you have something there! The date on the BMS PCB's in your picture is 2009, that would seem to be way too early for use in car production today. I sure wish we knew how to read the production date codes on the cells!

I wouldn't think the utility batteries would be spent in 3 or 4 years, but these could be "culls." Seems to be a weak, or bad, cell group in a statistically significant number of assemblies.

[Pure]

Also, if you bring up the issue of their packing, you need to tread lightly. This vendor has already threatened to not sell to us over seas customers. If packing them becomes too problematic, they may just say no more sales. Trust me when I say they really don't need our business. There is more than enough of a market in china for these things. They really don't "need" to sell them out of country.

I would like to know more about your inside information. How do you know shit about how the Chinese marked is?
I would say close to the opposite, but thats just my subjective opinion just as yours as long as you don't give us some proof.
It's like you want to feed the seller with arguments.

Dude, lighten up.

My inside information? This shit aint no secrete. But I guess none of them want cells with the specs like A123. lol

In China, electric bicycles are leaving cars in the dust. Last year, Chinese bought 21 million e-bikes, compared with 9.4 million autos. While China now has about 25 million cars on the road, it has four times as many e-bikes.

Read more: http://www.time.com/time/world/article/ ... z1trJRXzfA

And never did I suggest that none on ask for better packing. My post was short because I'm busy. Just that when you ask for better packing ask polity and don't be an ass. I've been reading post on here where members are giving this guy crap. I can only imagine how many emails he's getting and of those how many are getting their panties in a wad.

We are dealing with a company in a different country, we need to act accordingly.

[deVries]

I ordered 3 7s3p's and just got them today. took about 5 days from Shenzen to Phoenix. the delivery man missed me at my house, so I went to the airport depot and picked em up myself.

Thank you for your very detailed report. Obviously, packaging needs to improve.

One module per crate would prevent that "bowing issue". IMO.

Can you weigh your modules to give us the individual weight(s) & any variances or differences too, please.

Thanks!

[SlyCayer]

Can you weigh your modules to give us the individual weight(s) & any variances or differences too, please.

Is it me or it's hard to get the weight of the modules? I promise that if we do not have a weight by the time I get mine, I will provide a very accurate weight .

[oatnet]

I took my packs apart today.

Is it me, or do the BMS's STINK? I mean SMELL, really, really bad? The 28s3p had a (2) BMS, one on each end (dated 2010), and all three 7s3p had a single BMS (dated 2009). All but one of the 2009 BMS looked thicker and lighter, tacky to the touch, and I had to take them outside because they were stinking up the garage. I wanted to disconnect them anyhow because I didn't know if they were draining current.

The good news is that all of the cells on my 19v pack are the same voltage - bad that they are all low, but good that none are dead. Every cell of every pack has every voltage! All the the cells were in balance relative to their respective pack. Wonder if it helped that I was a good customer.

I like that the same screws are used to mount the covers and secure the BMS on both types of modules.
I believe that the painted metal seperators are a soft metal cooling fin, so having one side of each cell is enough. The endcaps have nice, big, metal-lined holes through them, providing an excellent mounting points. The 7s have horizontal holes, and the 28s has vertical holes, but I think you can remove the liner and use either set of holes.

Because of the different metal in each tab, the welds on the negative terminals are gold, and the welds on the positive terminals are silver.

1 IMG_1944.JPG (162.46 KiB) Viewed 772 times

Note the dowels demonstrating the vertical mounting holes on the 28s. Now that I have seen professionally installed balance wires, I feel better about my own work. I do appreciate the design feature of the wiring channel up the center.

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Note the dowels demonstrating the horizontal mounting holes on the 7s.

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Closeup of a horizontal hole

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Side view of a row of welds. You can see the different colors of the cell tabs. A very narrow gap between the buss bars, on the left.

4 IMG_1935.JPG (30.64 KiB) Viewed 772 times

A row of welds. A plastic cap sits on top of each cell pair, the tabs stick through, and the buss bar is welded at the top. The screws that secure the top cover of this pack go into knobs in the foreground, which are part of the plastic carrier. I think the tabs are tensioned between the plastic carrier and the buss bar, and I remember Luke saying the tabs couldn't move around or they'd stress-fail, so I figure that is part of their purpose.

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Closeup of a tab, and the weld in the upper left corner.

6 IMG_1936_crop1.JPG (56.13 KiB) Viewed 772 times

closeup on a row of welds, note the silver vs copper color.

7 IMG_1936_crop2.JPG (40.69 KiB) Viewed 772 times

On the left, the 2009 BMS that is normal, on the right one of the 2009 BMS's that STINK, are gooey, you can see the color and sorta matte finish on these.

8 IMG_1953.JPG (71.69 KiB) Viewed 772 times

7s (2009) vs 28s (2010) BMS, side 1 (click for large picture)

7s (2009) vs 28s (2010) BMS, side 2 (click for large picture)

Top of a 7s3p (click for large picture)

[deVries]

I took my packs apart today.

Oatnet, JD, thanks for the super pics. Man, those are excellent. Excellent commentary too.

If you get a chance no one has posted yet the weights of individual 7s3p modules. Would appreciate it if you can weigh yours & let us know.

Thanks!

[oatnet]

Can you weigh your modules to give us the individual weight(s) & any variances or differences too, please.

Is it me or it's hard to get the weight of the modules? I promise that if we do not have a weight by the time I get mine, I will provide a very accurate weight .

Just for you, deVries and SlyCayer. 30.6 lbs minus 14 screws, and when I removed the BMS/front cover it dropped to 30lbs even, so maybe 8lbs of packaging/wiring/buss bars on top of the weight of the cells. The others weigh pretty much the same, doesn't matter to me enough to carry them upstairs. The 28s (I am tired of adding "3p" to "7s" and "28s" ) is heavier than I want to lift at the moment.

I forgot to mention - I also like that '+' and '-' shaped holes are stamped through the buss bars that wrap around the terminals on the ends. Also, odd that on the postive terminal both pairs of bolt holes are live, and on the negative side only one pair is, the other is just a mount (see the third picture in my last post). Oh, the bolt holes for the power terminals are standard M6, I just screwed in one of the old bolts from my Headway cells. Judging by the screws that came on (1) 7s, a123 used red locktite on the bolts that secured the terminals, I usually use blue.

I am really pleased to be hands-on with a factory pack, so I know how to better package packs I build from 1s cells.

[deVries]

30.6 lbs minus 14 screws, and when I removed the BMS/front cover it dropped to 30lbs even, so maybe 8lbs of packaging/wiring/buss bars on top of the weight of the cells. The 28s (I am tired of adding "3p" to "7s" and "28s" ) is heavier than I want to lift at the moment.

You can skip the 28s as far as I'm concerned.

I'll be interested in your ideas about repairing that bad "3p cell", when you have time to do that repair. I think you got one low/bad or shorted 3p in a 7s, right...

...2 modules were at 22.x v and the third at 19.x v, so I assume it has a bad 3p cell.

Again, thank you JD for documenting everything you did today! Great stuff to know.

[oatnet]

It turned out that all the cells were at 2.75v in my 'low' 19v pack, but they all had voltage. Hopefully a charge up will fix things.

[SlyCayer]

Just for you, deVries and SlyCayer. 30.6 lbs

Thank you \o/

[davec]

.

[JRP3]

With three cells wired in parallel how are you going to load test a single cell without cutting it out?

[Harold in CR]

So, a 7S3P Module = 21 cells at 67V, correct ?? I have been trying to count cells, but, I get crosseyed.

Thanks for posting those excellent photos, Oatnet.

[Ypedal]

7S = 7 x 3.6 = 25.2v. .. call it roughly 24v

3P = 20ah x 3 = 60 ah

[EVPowers]

7S = 7 x 3.6 = 25.2v. .. call it roughly 24v

I thought these cells had a resting voltage of about 3.3v?

[Ypedal]

Yes..

Peak charge voltage of 3.6v ... they drop to 3.3 resting voltage.. 1C ~3 C discharge mostly above 3.0v .. drops like a rock below 3.0 to 2.0v fully empty and drained flat.

[EVPowers]

So here is the type of usage I'm considering for buying these packs
http://www.roperld.com/science/SunRoperTrips.htm

You can see in the third graphic down, that there can be some high-current draws. (290a, 250a, 225a, etc)
I'm not sure three 7s3p packs will be able to handle the load.

The voltage would probably need to be upped a small bit by creating another small pack of cells as well.

[ohzee]

While this pack size is to much for anything I would need I enjoy following this thread. I woke up about 3am last night and the
dream I was having was about this thread and these packs.. lol Just thought I would share - it was the great pictures Oat posted
I think that somehow had me dreaming about these packs - what they looked like what you could do with them.

Just thought I would come clean thought it was amusing.

[oatnet]

Hey thanks everyone for the kind words about the pictures, and thanks to all those who shared pics of the 54xx and CroMotor for me to drool over while I was waiting for them.

You can see in the third graphic down, that there can be some high-current draws. (290a, 250a, 225a, etc)
I'm not sure three 7s3p packs will be able to handle the load.

The voltage would probably need to be upped a small bit by creating another small pack of cells as well.

A single cell theoretically supports 600a (20ahx30c), so a 3-parallel cell will support 1,800 amps. A mere 290a will not be an issue. If you are trying to fit the battery to an existing setup, the controller will determine what voltage you require, and how many cells you need in series.

3.3v is the rated nominal voltage - aka the cell's resting voltage when half of its rated AH have been consumed. Hot off the charger, resting voltage is 3.65v. Ypedal and I undercharge our LiFe - to 3.60v and 3.55v/cell respectively - to minimize damage the cell incurs at peak charge.


On another note - am I the only one whose BMS's smell really bad? I think the circuit board itself decomposing, do I need to worry about the chemicals in it? Looking at the picture above that compares a good vs decomposing, you can see how the PCB seems to be balloning up and around the traces...

And of course, that makes me wonder whether they were intended to decay, or if it was a bad batch of PCBs.

-JD

[SlyCayer]

that makes me wonder whether they were intended to decay, or if it was a bad batch of PCBs.

I have never heard of decaying PCBs, correct me if I'm wrong, but ain't PCB mainly glass based?

The smell might be in a "Gel" coating? I remember opening up a HID Conversation Kit Ballast, and it had a gelly/silicone filled box and it smelled like shit but was there to protect the PCB from any liquids or elements...

Maybe...

[davec]

i do have a request for anyone who has the time so we can get a good idea about what we're getting here

1. IR test on one of the cells in the module
2. 1C test on a cell in the module to see how many AH they deliver

would be awesome

[deVries]

On another note - am I the only one whose BMS's smell really bad? I think the circuit board itself decomposing, do I need to worry about the chemicals in it? Looking at the picture above that compares a good vs decomposing, you can see how the PCB seems to be balloning up and around the traces...

Circuit boards are layers of resin & fiberglass...

on the right one of the 2009 BMS's that STINK, are gooey, you can see the color and sorta matte finish on these.

Since you mention "gooey" too, I think this somehow got exposed to or misted in some chemical that attacked the CB. Can you poke or scratch into the CB resin to see if it is softer & not hard on or near the surface?

I know someone mentioned using alcohol to clean CBs that had gotten dirty & that it works well.

Are you intending to use the BMS? Has someone learned how to do this already?

[oatnet]

you guys did a really good job
thanks for the great pics and for reviewing these modules for us
i do have a request for anyone who has the time so we can get a good idea about what we're getting here

1. IR test on one of the cells in the module
2. 1C test on a cell in the module to see how many AH they deliver

would be awesome

...crickets...

[oatnet]

Ghetto-balancing the 7s pack that had the 2.75v cells... So glad I made up a bunch of plugs for the single-cell chargers that have alligator clips on the other end, they come in handy time and time again. I'm hoping that a nice, slow 2a charge on these 60ah cells will bring them back from low v, hopefully they were just at a low SOC when they got shipped, At 2a it will take 30 hours just to generate 60ah, probably another 15 hours just to make up for effeciency losses.

We need a smellavision so I can share my BMS aroma. It could just be a coating on the boards - but it really smells foul to me, hard to believe they would put it in a product.

It just occured to me that maybe they aren't actually BMS, maybe they are just monitoring sensors that feed run by an external BMS over canbus via that other jack that is on the board. If anyone who can read circuits can tell from those big (click on) pictures I posted, I'd love to know what you thing they do. those wires are pretty thin.... Still and all, I don't see another way of balancing those cells, and they are in fact in balance. I thought I saw something about a123's "active balancing system"

-JD

IMG_3332.jpg (170.69 KiB) Viewed 660 times

[deVries]

I got an update from Sutho saying that he will be getting his 22 modules of 7s3p next Tuesday, so by Wednesday next week we should have some good info about what a bulk order looks like.

i do have a request for anyone who has the time so we can get a good idea about what we're getting here

1. IR test on one of the cells in the module
2. 1C test on a cell in the module to see how many AH they deliver

Since the cells are welded together in a 3p configuration, I seriously doubt someone will "destroy" their module to extract a single cell from the 3p modules.

That's just too much risk, work, etc. unless one is doing a science paper or analysis of high numbers of test cells for that purpose. One cell from one module would not really tell us much about the 100's of modules and thousands of cells available, so it's statistically meaningless and useless information, IMO.