Prismatic cells

Hi folks,

unexpectedly I've got some laptop barreties with prismatic cells. First I wanted abondon this offer but later on I thougth I will give them a try.
It was a really hard work to pull them out of housing - it has to be done very carefully, not to bend them, not to press, not to destroy, etc . I've managed it.
The cells are from ATL. The measured capacity is in average about 1500 mAh.
The last time there are more and more prismatic cells around from flat laptops, tablets and other electronics and so I thougth we shall talk about them...





Then I started co connect them in parallel and after in serial to get a source of 24V.
Let's see waht will happen. The project is still under construction ;-)





I will be back later on...

BigBen

Hi BigBen,

I'm glad someone is finding a good use for these. With 18650 cells being harder to come by, people will have to start thinking about these types of cells for their powerwalls instead.

Neat, I've never seen these used in a powerwall before. I think they need room to expand in case they are discharged too fast, how tight is the duct tape?

This grey tape is not that tight. They have enough room to extend. The battery housing was even tighter. They were fixed inside with a kind of black hard rubber which was not elastic. And according to the documentation they extend 0,1mm per cell. I do not want to discharge them that hard ;-)
Well, I have read somewhere - I do not remember exactly the details - that some company even press them gently to avoid the deviation of the cells. It will give some advanteges. Sorry, but I really forgot where I got this infos other way I will for sure quote the source.

BigBen

I think the .1 expansion is what happens when the electrons wedge themselves into the cathode. The expansion I was thinking about was the gas. If each cell puffs up 2mm and there are 20 in a pack, that's 40mm.

I'm interested to see your progress.

The whole point of wrapping them up IS to prevent them swelling up.
These cells are far less likely to puff up if packaged properly.

Puffy cell = dead cell.
The gas comes from the breaking down of the electrolyte within the cell, eg water => hydrogen gas.

I don't think the reaction can be stopped with compression. But it would keep things in place. So compression is good until they pop.

station240 said:

The whole point of wrapping them up IS to prevent them swelling up.
These cells are far less likely to puff up if packaged properly.

Puffy cell = dead cell.
The gas comes from the breaking down of the electrolyte within the cell, eg water => hydrogen gas.

Click to expand...

Yes, there where few inflated cell when I was pulling them out. I put them all in a separate box (not on my picture). But really maybe only 10 pieces - not that much.
They even smell a way seldom one can not compare that smell with something else - really special unpleasant smell.
The others are solid and in best condition. So the yield was very good even in comparison to my expirience with 18650 cells in other batteries.

BR
BigBen

Given so many of those away - they scare me but good too see them recycled

station240 said:

The whole point of wrapping them up IS to prevent them swelling up.
These cells are far less likely to puff up if packaged properly.

Puffy cell = dead cell.
The gas comes from the breaking down of the electrolyte within the cell, eg water => hydrogen gas.

Click to expand...

Correct!

BigBen got any hints on how to remove these prismatic cells from the laptop battery casing ?
I'm patient enough to slowly pry them out, should I decide to use them myself.

Hi station240,

station240 said:

BigBen got any hints on how to remove these prismatic cells from the laptop battery casing ?
I'm patient enough to slowly pry them out, should I decide to use them myself.

Click to expand...

well, what hints do you expect?
The batteries I remove the cells from came from HP.
First I bend - not really bend but tourque them - holding them tight with my left and right hand on the edges. When I hear cracking sound, I knew they are released inside. Such movement help much but has to be done as always carefully.
Second: open carefully the housing. This is a shitty process. If you are pulling away the upper plastic, take care not to press the cell but pull on plastic (housing) and destroy better the upper housing and not the cell.
If the upper cover was away then you have to remove/pry the cells outside of the lower/carriying housing. They were stiched with double sided Scotch tape - it was night mare to release them. Use something flat, wide und not sharp to lever them a little bit and do it step by step. If the cell(s) is/are taken out one have to clean them all.

Actually it is very time consuming job. But I got very reasonable cells and the capacity is also OK. Now I'm bulding up my blocks and after the whole 27V battery.

Good luck to you!
BigBen

keep the charge voltage low.

Ive induced puff with high charge voltages on these, every time.
Same with phone batteries, once you go over 4.35 puffy
(takes a while, needs more v)

Jehu did the same charging to 5v with a really large one :

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No heat, just swelling

Heat gun helps heaps when removing batteries (dont be afraid of adding a little heat)
Or freeze them for a little while, then glue gets brittle. (found heat to be more effective)

Hi 3nergE,

3nergE said:

keep the charge voltage low.

Ive induced puff with high charge voltages on these, every time.
Same with phone batteries, once you go over 4.35 puffy
(takes a while, needs more v)

Click to expand...

I never do load any Lithium (Li-Ion/LiPo) cell higher then 4.20V.
First there is no sence to load that high because there is almost no energy to harvest between 4.20 and let's say 4.00V.
Second, it reduce the life time of the cell dramatically. My working voltage range is between 4.1 (cut off) and 3.5V. In this range the cell can last almost up to tousand(s) cycles and has the most energy.
Third, I do not do any research with overloaded cells - it's enough for me to participate on the expirience of other people and yes, it destroys the cells.

3nergE said:

Heat gun helps heaps when removing batteries (dont be afraid of adding a little heat)

Click to expand...

I disagree with you. Really I'm afraid of overheating and I prevent the cells from any heat above 60C - again it reduces the life time significantly.
In my basement I have almost constant temperatures between 17C in winter and 23C in summer without any condition (heating/cooling). This is the best range for the cells - for starage and also for working.

Thanks for comments!
BigBen

Dont be afraid of applying external heat to cells, its heating them under load discharge or charge that is the issue, not storage heat.

Casing @ 50c under chemical load is way different to some external heat up to 50c, the mass is not heated, only the outside.
Its way more thermal energy to get a cell to 50c under chemical load - big difference.

And charging cells to 4.35-4.45 is phone batteries norm, not lico / lipo / lion for sure. I should have been more clear.

Im the same, 4-4.1 cutoff for extended life and safety. Imagine my rigs going to 4.20+ with no bms or fusing (squeeel)

BTW, heat gun needs to get a cell to hundreds of degrees to do anything interesting.

If you have a small oven and a good temp gun, cap test a cell, cook it to 70c, cool it and cap test it. youll be surprised. Ive gone to some pretty extreme temps and no capacity issues, autopsy didnt show any chemical change either. It really needs to be chemically driven.

But, hey, I wasnt advocating cutting them out with a torch, just get the glue softened, i use my gun on the 18650s to get the glue malleable, then i rub it off with a bit of baby powder, works really well. And with your hands in the line of fire, youll OUCH before they get hotter than 50c (thats the human skin pain threshold)

The reality is if you damage the cells mechanically getting them out by being too carefull and not extracting them using other methods, its far more life reducing.

kind regards

Hi 3nergE,

3nergE said:

If you have a small oven and a good temp gun, cap test a cell, cook it to 70c, cool it and cap test it. youll be surprised. Ive gone to some pretty extreme temps and no capacity issues, autopsy didnt show any chemical change either. It really needs to be chemically driven.

Click to expand...

Really, you have done this test? You have cook them? Amazing, people get idea! I would never get such toughts!
I hope you didnt eat em
Well, I have learn something. Thank you for sharing your expirience!

3nergE said:

The reality is if you damage the cells mechanically getting them out by being too carefull and not extracting them using other methods, its far more life reducing.

Click to expand...

Yes, that wright, you can destroy them mechanically and then the game is over.
Btw, I'm almost ready to connect prismatic cells to blocks. I hope to show some pics on sunday.
Now I'm testing the capacity and it looks very good!

Best regards
BigBen

Yea, Im a bit mad, ppl say dont do this or that and cant quote science, so i go and research the how and why, then do stupid stuff to prove it to myself and my mates.
Its a bit dodgy, but everyone learns a bit. I just cant help it. <grins>

When you know the acceptable variables, its not as risky.

Really interested to see how your project progresses, as i just dumped my prismatics too. Never even thought to use them since my design just wouldn't accommodate that cell format.

Happy to help any way I can, if I dont already know it, ill find out, just so i can share mate.

Keep it up, your doing what I wouldnt dare, im like Big Meat Pete, prismatics scare me. I prefer my bombs 18650 shape <chuckles>

kind regards

3nergE said:

.......... autopsy didnt show any chemical change either.

Click to expand...

What methods and processes did you use to come to this conclusion ?

Shiney new cells, or high % of original capacity cells have lovely looking foils.
Old cells that have been taken care of have uniformly discolored foils.
Abused cells get spots, burns and other fuglies and major discoloration.

Again, have to stress, my testing is 18650 format, check jehu's chan for his tesla pouch 'pillow' @ 5v
He did an autopsy after charging to 5v all day, no heat issue, then load test (where it was affected for sure)

Nerdvill did a nice autopsy of cells being welded vs sodder + autopsy

YT has a number of autopsies if your a bit afraid, or dont have a dremmel to cleanly open stuff up.

kind regards

So you are just opening them and looking for visual signs of change, rather than any form of chemical analysis.

got it ......