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What to do with 160x 20ah 3.2v Lipo pouch cells?
#1
I have a line on 180 pouch cells.  They are 3.2V 20ah each and I can get them for $5 a piece.

I'm totally new to this stuff, and I've been watching youtube videos that got me interested in the idea of a DIY powerwall, but almost everyone is using 18650s.

These pouch cells seem really awkward to work with.  Is this a good enough deal to be worth it?  Any tips or links to clever ways to arrange these types of batteries into useable battery banks?

My math so far:  I figure 20ah x 3.2v = 64wh per cell x 180 cells = 11.52kWh

If I went with a 12 volt system it would be 4s45p for 12.8v and 900ah.  Is that correct?

I need to figure out BMS and charging solutions on top of figuring out how to configure wire/connect and store these....

I'm leaning towards a 48 volt powerwall.  What would I need to test, balance, charge etc.  What type and number of BMS would I need?  How do I figure out how many BMS units I need?  Do standard MPPT solar charge controllers work because our BMS units take care of the differences, or would I need a special charge controller for Lipo?

Sorry I don't know enough yet to even ask the right questions.  I'm trying to get a crash course on the project idea so I can jump on these batteries.

Thanks for helping a noob Smile

Nate
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#2
Interesting....
Do you have a model number or a link on the cells so we can get a better look at their specs?
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

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#3
you would probably want to spot weld them
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#4
(08-10-2018, 06:12 PM)Korishan Wrote: Interesting....
Do you have a model number or a link on the cells so we can get a better look at their specs?

Not many links (english) to chose from when searching, but part number is: PE-F20-09155225.  

Only useful info I found on a quick scan through was this:
Model:  PE-F20-09155225
AH:  20.000 Ah
Type:  Pouch
Chemistry:  LiFePO4
Dimensions: 226.0mm x 155.0mm x 9.2mm
Weight:  555.0g
Charge:  20.0A
Discharge:  40.0A → 100.0A



Also, This is the most elegant solution I've seen for building pouch cell banks:     In case video doesn't embed below:   https://www.youtube.com/watch?v=O3VtYwJz78g




Any idea where to get something like this?  

Or how to embed a video  Smile  I chose "share" from the video on youtube, then "embed", then pasted the above worthless line of html....
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#5
Youtube-Links-Video-and-URL Wink

Interesting design for putting them together.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at https://discord.gg/c7gJ5uA
(this chat is not directly affiliated with SecondLifeStorage)
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#6
Star 
(08-11-2018, 12:03 AM)Korishan Wrote: Youtube-Links-Video-and-URL  Wink

Interesting design for putting them together.

It worked!  Thanks Smile
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#7
Yes , your maths is correct ... these look like a good deal , normal price is $20 each

the lower voltage makes these perfect for 12V system (4s) ... each pouch is equivalent to about seven 18650 cells so once you figure a good way to wire them up you can build quickly ..

It shouldn't be too difficult to do ,I would have a go ....all the other issues, charging etc , can be dealt with latter...

These cells are rather wasted on powerwalls ... high discharge makes them perfect for e bikes ... big market , you could start a company making ebike batteries if your supply is reliable at that low price .

I expect there will be more of these flat cells in the future as products get more slimline this is where the future lies ...
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#8
These would be good cells & hold a lot of juice. Yes grab them!
You can solder the tabs.
To join them you can use a piece of fibreglass PCB board with 100% copper (eg not etched).
You cut slots in the PCB material to match the tabs.
Copper side away from the pouch, you'd thread the tabs through the slots, fold flat & solder down, ie like the video.

In the video, the method used with thick double sided tape would put a pressure point at one end & not support the other - not keen on that!
Maybe use thinner tape &/or more strips of it?
Running off solar, DIY & electronics fan :-)
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#9
(08-11-2018, 05:56 AM)Redpacket Wrote: In the video, the method used with thick double sided tape would put a pressure point at one end & not support the other - not keen on that!
Maybe use thinner tape &/or more strips of it?

I didn't think about this when I was watching it. But here's another idea. Instead of using the foam tape, how about using the accordion style filing box, then add layers of foam rubber in between to take up any slack. The foam rubber would be glued/taped to the box leafs.

I remember from an earlier post that prismatic cells like these should be sandwiched and compressed slightly to keep them from swelling. Otherwise they may blow up like a balloon for some reason. Not sure on the chemistry reasons

There was someone on here that had a bunch of those cells and made a jig to hold all of them. I don't remember who that was, tho. I think they made the whole thing out of wood and then clamped the cells in place afterwards.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at https://discord.gg/c7gJ5uA
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#10
So I like the idea of modularity, so I'd like to create 4 12v battery banks and wiring them in series for a 48v system.  This would give me the ability to reconfigure as the need may arrise to use a 24v or 12v setup.  This would give me four battery banks, 12v and 220ah each with 4s11p.

Are there any problems so far?  I'm willing to forego the modular nature of this and just make one giant 48v bank if the above would cause problems I haven't thought of. 

Further demonstrating my ignorance, I have no idea what type of balancing or charging these would take.  I've read a lot of relevant posts, but I don't speak the technical language well enough to follow along most of the time.

Assuming modular works, let's assume a single bank, 12v 220ah wired in 4s11p.  Where do I need to have bms' wired?  Do I need 4 BMS modules, 1 per series string?  What type of bms would you guys recommend (I need to figure out how much this is going to cost me on top of the batteries).  I saw one gentleman running these pouch type batteries for his RV and he used  http://www.electriccarpartscompany.com/3...Equalizers    to balance.  Is a BMS seperate from these?  How do I monitor cell heatlh?  

What type of unit would I use to test, charge, and discharge/measure these types of batteries?  

Thanks, 
Nate
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