# A123 7s3p packs and other options



## crashedup (Oct 28, 2008)

wow verry interesting, a little risky but what a price!


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## mizlplix (May 1, 2011)

So........any more info?

Miz


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## crashedup (Oct 28, 2008)

Go see the link to that other site, there is one guy on that site who decided to order 22 packs, were all waiting to see how that ends up.


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## MN Driver (Sep 29, 2009)

The 42s3p pack would be 134.4v and the cells seem to be at least 18Ah so 134.4v 54Ah. 7200wh or so. Roughly what lead-acid users usually use. They could put 2 of those together either parallel for the same voltage or two in series for a 14400wh pack and get better range than most of the lead-acid guys can manage. 14kwh in a 300wh conversion would be about 40 miles range with a little buffer at the end, more miles for if the donor vehicle is a more efficient one. IMHO I'd get the 28s packs and series those together because then if there was an issue you wouldn't have a huge pack out of commission, buy an extra 28s3p pack as a spare in case these A123 cells/packs disappear and we have nothing to replace cells or packs with later on.

If the guy buying the 22 packs of 7s3p finds that they are good. I'll be looking into getting 4 of the 28s3p packs(one as a spare) and two of the 7s3p packs for a 98 cell string. Should be a good 17kwh if I figure the pack gives 18Ah per cell(54Ah for the pack). If they can fit in my micromachine of a car, I'll be elated. Hopefully the shipping costs aren't too horrible and the guy buying the 22 packs finds them to be good because these things are cheap.


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## Batterypoweredtoad (Feb 5, 2008)

The discussion on why these are available is interesting. The new picture in Victpowers ads is interesting: 









The "Vibration and Shock No Pads" stickers make me wonder if that particular module was a test module. I have ordered a 28s3p and a 7s3p to get a good look at them and see if they are usable.


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## Brute Force (Aug 28, 2010)

Toad,

Hope your modules show up in better shape then the ones over on Endless Sphere. The crating so far has been awful.

My curiosity has been piqued. I've been dealing with Mavizen about buying new modules, but replacing the recalled modules has been A123s top priority and my purchase has been back burnered for the foreseeable future.

Anyone looking into these modules should steer clear of the 42S3P module being advertised. I have information that indicates A123 never manufactured this configuration. And Victpower's picture of the module has 84 cells in it, not the 126 it should have. And the one person who ordered some has been told they are on back order after he placed his order and sent his money.

If you don't want to deal with China, Jack Richards at EVTV says he will order these through his contacts for interested parties. Keep in mind the module he tested ended up as a door stop. May have been a bad module, may have been his methodology, or a combination of the two (I'm not in a position to judge).


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## Batterypoweredtoad (Feb 5, 2008)

I have been watching the endless sphere thread closely. The packaging has indeed been atrocious. I am really anxious to get a couple of modules and disassemble them to see if the cause of failure is obvious. I am leaning towards attempting to replace 3 cell parallel groups at the buss bar welds instead of removing individual cells. They look to be spot welded together. It might be possible to cut the buss bar right at the spot weld and spot weld an overlapping piece when replacing the 3 cell group. If that doesn't look do-able then maybe dremmeling the weld off of the tab and spot welding a new cell in will be possible. This may all be a waste of effort if I cant salvage the modules, but I will at least end up with a bunch of a123 cells. Many people here know way more than me about this stuff so I will be posting lots of pics and questions.


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## Brute Force (Aug 28, 2010)

The cell tabs are not spot welded. The tab is cut short, inserted into the accordion folded bus bar, and laser welded along the entire tab width. One cell tab is copper, the other is aluminum. From the color difference in the weld, it's obvious which one is which.

Use a dremel to grind the weld off and relive the crimp of the accordion fold that cell will come free of the bus.

Keep in mind that the groups of three are all daisy chained together with no place to separate them out.

My personal opinion is that replacing cells/groups of cells in the these packs is impossible.

I'm looking to hack the battery management boards. Would you be interested in selling the ones off yours if you cut the packs up?


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## Batterypoweredtoad (Feb 5, 2008)

I'm not sure about the battery management boards yet. I am hopeful that I will be able to salvage the packs. It hadn't occurred to me that the tabs were welded to the bussbar the full width of the tab because of the bussbar not being welded across the full width of the bussbar. It makes sense now that I think about it. (Edit-I correct my correction. The tabs are wider than the weld. There may yet be a salvageable bussbar after dremeling the weld)

If you look at the following pic you can see where the bussbars for adjoining groups of 3 cells are spot-welded together. It is at that junction that I think I might be able to cut out and spot-weld in a new 3p group.


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## Brute Force (Aug 28, 2010)

You are correct, the tab is the same width as the bus and it is not welded all the way. Looks like about 2/3 to 3/4 of the width.

I hadn't noticed the seam in the bus where the cell clusters meet.

Keep us posted on your findings.


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## Batterypoweredtoad (Feb 5, 2008)

I received my 7s3p module, my 28s3p module and my 12 bare cells. The 28s3p was packed with minimal foam in a tight fitting box and arrived in decent condition. It is missing both BMS boards. The 7s3p and 12 bare cells were in the same box but separated by a wood divider and well isolated in with foam and Styrofoam blocks. The 28s3p module is in very good physical condition and complete and the bare cells appear to be fine. 

I now need to test the cells and modules. What does the group recommend? I know the PL-6 is popular with the bare cells but is it convenient for the modules as well?


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## Batterypoweredtoad (Feb 5, 2008)

Well my 28s3p module checks out at 92.0 volts for a parallel cell group average of 3.2857 volts. My 7s3p module measures 23.0 volts for a parallel cell group average of-wait for it................3.2857 volts. That says no dead cell groups. Now I wait for the Pl-8's to start shipping again (company on vacation) to get some capacity and resistance tests. If those go well I will order more modules.


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## Ziggythewiz (May 16, 2010)

Do you have any way to monitor the charge discharge without waiting for the PL8? With something like a JLD404 you could do both. Even if you had to monitor manually, just getting in one charge/discharge without having to wait long would be good since the bad ones are reported to often fail in the first cycle.


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## Batterypoweredtoad (Feb 5, 2008)

I can currently test voltage and do nothing else. I am just beginning to gather equipment to evaluate these modules. Any advice on how to proceed would be appreciated.

The end goal would be a 3x28s3p + 2x7s3p pack for a total of 98s3p or 313.6 Volt, 60 AH pack.


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## Batterypoweredtoad (Feb 5, 2008)

BTW-I would say they both appear used. I doubt it is the first use for either module.


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## Ziggythewiz (May 16, 2010)

Do you have a means to charge and discharge them in their current configuration?

Looks can be deceiving. I would expect a pack that's been installed in a car, pulled, and shipped to China and back, as some of these supposedly have, to look a little worn.


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## Batterypoweredtoad (Feb 5, 2008)

Ziggythewiz said:


> Do you have a means to charge and discharge them in their current configuration?


No. I would like to be able to with whatever I purchase. I am looking for recommendations. 



Ziggythewiz said:


> Looks can be deceiving. I would expect a pack that's been installed in a car, pulled, and shipped to China and back, as some of these supposedly have, to look a little worn.


True. They are worn and possibly overused OR unused. I honestly don't know. I do know they are interesting and that is about it.


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## Elegancec (May 23, 2012)

Hello,

do you know the weight of the complete module 28sp3? Does the ending 28sp3 stand for 28 in series and 3 parallel so 60Ah and 28*3,2V = 89,6V?
`
Is it possible to get voltage information of all cents from the BMS system?
If I got it right, you these cells are already built in cells which had been dismounted and now sold via victopower, so they are definitely not new ones.
Did you get values about the internal resistance with your delivery? At the moment I can not test the cells because of leak in equipment. This would be interesting for me.


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## Batterypoweredtoad (Feb 5, 2008)

Elegancec said:


> do you know the weight of the complete module 28sp3?


I believe they are 106lbs



Elegancec said:


> Does the ending 28sp3 stand for 28 in series and 3 parallel so 60Ah and 28*3,2V = 89,6V?


Yes.
`


Elegancec said:


> Is it possible to get voltage information of all cents from the BMS system?


Yes, not by me, but it has been done.



Elegancec said:


> If I got it right, you these cells are already built in cells which had been dismounted and now sold via victopower, so they are definitely not new ones.


They are likely used. Some of the 7s3p modules I've seen looked pretty new, but all the 28s3p have looked fairly rough. The dead module rate has been high with both.



Elegancec said:


> Did you get values about the internal resistance with your delivery? At the moment I can not test the cells because of leak in equipment. This would be interesting for me.


Victpower doesn't have the cells in front of them. They tell the "factory" (more likely central warehouse they ship from after you order) to ship them after your payment is received. You don't get any information, you often get bad modules with visible damage, and the 28s3p often don't come with the two BMS or the BMS covers. Victpower is very clear that there are no guarantees and they don't take paypal (because earlier transactions are in dispute). If you get modules at lower voltage than they claim they tested or missing BMS they try to get you to buy more stuff so they can cut you a very very slight discount to make up for earlier failures. 

Purchasing these modules means you accept a low voltage module about 1/2 of the time. If those numbers work for you then it may be worth the risk.


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