Li-Po Power Wall?

A

Alyas Junior Abdul

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Joined
May 6, 2017
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Hello Everyone, I have just joined the forum and made an introduction.
I have 2500pcs of 2200mAh li-po battries, I know li-po batteries are not the best options, but thats what I have at the moment.
I would love to go ahead and start the build. My experience with lips batteries aren't bad at all, I never had any fail on me, thus I don't know why it can't be used. But I thought it would still be wise to get some professional advice.

The power wall be kept outside my house in a small concrete brick storage, just to be safe.
 
Welcome to the forum :)

Lipo has a bad reputation. That's true. Yousay you have experience with them so that's good and your power wall is going to be well positioned outside. I say all the best with it and look forward to seeing the plans for your build.
 
@Wattsup Thanks for your response mate, appreciate it. I am still doing some research, unfortunately due to work commitments, progress will be slow.
at the moment I am thinking how to physically put the cells together. I have also not decided between 12V (3s, 800P) or 24V system (6s, 400P) configuration.
 
I think anyone that gets into this for long enough ends up at 14s.
Higher voltage, more efficiency, less current which also means less voltage drop.
 
Welcome and as long as you know what and how they work go ahead :) As said having them in outdoor shed will if "good forbid" not cause any bigger harm :)

Note that 7s is better suited for 24v meanwhile 3s or 4s for 12v depending on what equipment you are going to use.

Grouping thouse batteries together may be the biggest challenge but in the end its just a matter of start working with them!
 
Build some shelves/holders for the packs and make some paralell connector harnesses to parallel up multiple packs.
Terminate to a long busbar and repeat.
Careful about wire size selection and loading/current carrying capacity for the harnesses.

Are they RC hobby LiPos by any chance? What type of connector if any is on them?
 
AussieJake: They were cells from mobiles
 
Ar ok... So no connector.. just recessed tabs that the phone would connect to?

Yeah i think it's possible... But you're going to have build some sort of holder for them. For use in the running system but also for testing them individually.

Another issue is that even though they're recycled, you want something that you can continue to get your hands on... So when some start failing you can replace them individually..
 
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AussieJake said:
Ar ok... So no connector.. just recessed tabs that the phone would connect to?

Yeah i think it's possible... But you're going to have build some sort of holder for them. For use in the running system but also for testing them individually.

Another issue is that even though they're recycled, you want something that you can continue to get your hands on... So when some start failing you can replace them individually..
Click to expand...

I have been thinking of stacking them front to back and connecting to a bus bar.
Ithink its one of them build it where you plan as you begin to work on it.

Blow image is a very rough sketck of how i plan to tackle this problem.

image_watlgn.jpg


image_eycmcp.jpg
 
AlyasJuniorAbdul said:
I have been thinking of stacking them front to back and connecting to a bus bar.
Ithink its one of them build it where you plan as you begin to work on it.

Blow image is a very rough sketck of how i plan to tackle this problem.
Click to expand...

Seems like a good job for a 3D printer. What are the dimensions of the cell? How many in one stack?

I will whip you up a quick 3D model.
 
Yeah that could work..
They're nice looking LiPos.

You could just do multiple single row of cells stacked back to back... And make large capacity 3.7v packs.
Then paralell them as you desire..
12v (3or4s) 24v (7s) or 48v (14s)
 
Hello Abdul,

please see also my post about the prismatic cells. You will find my work with this cells here:

http://secondlifestorage.com/t-Prismatic-cells?page=1

I would suggest to build four separate battery blocks. 2500:4=625 cells per block.
If possible go to 48V system - it is more effective. It means you would have 14 serial blocks.
625:14=44 cells in one parallel row. This is a dimension you can handle during the build up. Otherway it will be too big to handle it while you are soldering and etc.
After you have build up your banks you can connect them in parallel.
Energy you'll got is: 2,2Ahx44=96Ah and this amount times four is about 400Ah! It is pretty good for a 48V system!

Good luck to you!

BigBen
 
AussieJake said:
Yeah that could work..
They're nice looking LiPos.

You could just do multiple single row of cells stacked back to back... oAnd make large capacity 3.7v packs.
Then paralell them as you desire..
12v (3or4s) 24v (7s) or 48v (14s)
Click to expand...

Yes they are and they are all almost brand new and never used.
I'm still thinking about it, however I think I might go with a 48V system to reduce the I^2*R power losses. And to be honest I think I would like the look of a 48V system.
 
BigBen said:
Hello Abdul,

please see also my post about the prismatic cells. You will find my work with this cells here:

http://secondlifestorage.com/t-Prismatic-cells?page=1

I would suggest to build four separate battery blocks. 2500:4=625 cells per block.
If possible go to 48V system - it is more effective. It means you would have 14 serial blocks.
625:14=44 cells in one parallel row. This is a dimension you can handle during the build up. Otherway it will be too big to handle it while you are soldering and etc.
After you have build up your banks you can connect them in parallel.
Energy you'll got is: 2,2Ahx44=96Ah and this amount times four is about 400Ah! It is pretty good for a 48V system!

Good luck to you!

BigBen
Click to expand...

Hello Ben

Thanks for your post mate, I just had a thorough read of your post. I must say you have done a beautiful job, they look really nice, I might use some as inspiration in my build.
I was thinking of building a case out of woodor some kind of plastic, to protect the cells from accidently damaged. Also like some other user suggested they might get puffy. So I might actually add double sided foam tapes, between the cells prior to stacking them together, it should have a clearance of about 3me. What are your thoughts?
 
AlyasJuniorAbdul said:
BigBen said:
Hello Abdul,

please see also my post about the prismatic cells. You will find my work with this cells here:

http://secondlifestorage.com/t-Prismatic-cells?page=1

I would suggest to build four separate battery blocks. 2500:4=625 cells per block.
If possible go to 48V system - it is more effective. It means you would have 14 serial blocks.
625:14=44 cells in one parallel row. This is a dimension you can handle during the build up. Otherway it will be too big to handle it while you are soldering and etc.
After you have build up your banks you can connect them in parallel.
Energy you'll got is: 2,2Ahx44=96Ah and this amount times four is about 400Ah! It is pretty good for a 48V system!

Good luck to you!

BigBen
Click to expand...

Hello Ben

Thanks for your post mate, I just had a thorough read of your post. I must say you have done a beautiful job, they look really nice, I might use some as inspiration in my build.
I was thinking of building a case out of woodor some kind of plastic, to protect the cells from accidently damaged. Also like some other user suggested they might get puffy. So I might actually add double sided foam tapes, between the cells prior to stacking them together, it should have a clearance of about 3me. What are your thoughts?
Click to expand...

Hello again,

a wooden or plastic case is allways good. I woudln't stick the cells together one by one but as a pack all at once with tape.
The cells need a little bit place for deviation, but for shure not that much. My cells need 0,1mm if it is fully charged and when the room temperatures are high. My room temperatures are almost allways about 20C (because in basement of house) and my voltage working range is about 3,6xx to 3,9xx volts. So I never observed some deviation or changes of my battery dimension. It works now since Dec. 2016 fully uncpectacular.
If you are living in a hot climate area you have to think about deviation. On the other hand the spec for my cells is saying that the cells have to be putted into a tight housing. And they were inside a thight laptop battery housing - let's say a little bit pressed together.

If it is possible do an actyllic housing - you can allways observe your cells and for sure it would look also very good!

Good luck to you!
BigBen
 
Hello Alyas,

to go with 149 cells at once in parallel would be a little bit difficult - because of handling.
I also have diveded my cells in smaller blocks and have created 4 batteries of 7s30p.
So you can also devide your 149 by 4 => 37 pieces x 14 = 518 cells. What would be the weight of such a battery? I would estimate about 15 kg if not more! To handle a battery of 14s149p you would need a fork lifter!
You can connect four batteries after they are build up in parallel and that is it! Like Peter is doing with his batteries.
My batteries are working smooth - nothing special, even boring ;-)

Kind regards
BigBen
 
[ATTACH said:
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BigBen pid='5546' dateline='1495031741']Hello Alyas,

to go with 149 cells at once in parallel would be a little bit difficult - because of handling.
I also have diveded my cells in smaller blocks and have created 4 batteries of 7s30p.
So you can also devide your 149 by 4 => 37 pieces x 14 = 518 cells. What would be the weight of such a battery? I would estimate about 15 kg if not more! To handle a battery of 14s149p you would need a fork lifter!
You can connect four batteries after they are build up in parrallel and it is! Like Peter is doing with his batteries.
My batteries are working smooth - nothing special, even boring ;-)

Kind regards
BigBen
Click to expand...

Hello BigBen

Yes, it has proven to be difficult to parallel 149 cells. I have decided to make 4 blocks of 37 cells in parallel by 14 in series.
below is a rough diagram of what Iplan to do.


image_vqnpcn.jpg


I will be using a custom made BMS system. the approach that I will be taking towards the BMS is not a very efficient method.
But It will be a lot cheaper than what is available at the market. I will be using one small module to monitor each individual cell, as of now, I just want to have over and under voltage protection for each parallel cell groups, they will use I2C communication to send their data to a master micro controller, but the module itself will be doing all the monitoring and balancing. But more to come on that later down the build.
 

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Hello Alyas,

your schematics looks good to me!
The BMS is really special thing to be planed very carryfully. The cheap bleeding BMS are not that good. The better ones costs much of money.

Good luck
BigBen
 
Hi Alyas
Very interested in your project. I have just received 1.5 tons of these batteries but pressure of work is going to slow me down. I'll post when I have some progress
 
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