Prismatic LiCo

[Jackolantern]

Hi all,
Can anyone here explain what "Prismatic" means in relation to cobalt based lithium bareries? I have been dumpster diving at work and come up with a large array of discarded laptop batteries. Each one that I have opened till now has had one dead cell. I just opened a couple IBM ones and they have flat rectangular batteries from Panasonic type is CGA103450, datasheet reads, Lightweight prismatic mode.
So what does this mean prismatic? I have noticed that they are all at an exceptional low voltage, something like 1.6v so I am thinking that these are different that the regular laptop cells, those have all been around 3.7 - 3.8 except the broken cells.
Could anyone explain to me what the difference is with these "prismatic" cells? Are they in some way better, can they handle such a dep discharge, or should I just dump them with the rest of the broken cells?
THanks.

 

[dogman dan]

Near as I could tell, prismatic means pouch cells in a box, as opposed to round cells in a box. Square format, but not naked or near naked foil pouches.

As far as specs go, I think with some square formats the discharge rate suffers. Gets worse, the bigger the size of the cell. While the best c rates are found in the smaller round cells. Something to do with the distance electrons have to travel to get to a pole.

 

[Jackolantern]

So for the rest they are the same as any other lithium battery, the low voltage stands for danger, i should just chuck them out right?

 

[wesnewell]

Being a laptop battery, they probably drained down to that voltage very slowly. I'd try charging them back up very slowly (<1C) and see what they do.

 

[ctirad]

Prismatic LiCo = LiPo

 

[spinningmagnets]

Here's the LONG thread from DrkAngel making ebike battery packs from salvaged laptop discards. The only conclusion I remember from it was to ensure that you make a large pack so the C-rate is as low as possible (20-Ah?), and even then it is risky...I have not personally done this and I cannot give a recommendation on how to proceed.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=26383

 

[dogman dan]

Yeah, lico discharged below 2.7v is considered a risk. I also know little about laptop cell pack construction, and get jumped on for discouraging building packs from laptop cells. But I'll stand by the statement that building from overdischarged cells is risky.

But risk is evaluated by you. Let's just say it's not worth it if you do have money to buy good cells.

 

[kZs0lt]

The term 'Prismatic' refers to the form factor(shape) of the battery cells.

Laptop cells come in either cylindrical or prismatic form.
By far the most common cell geometry used in laptop batteries are the 18650 cylindrical cells, which are a cylinder with 18mm diameter(9 mm radius) and 65mm height.
But prismatic cells are also used like the Panasonic CGA103450's, with physical dimensions: 10mm depth, 34mm width, 50mm height.

You can find the datasheet here: http://www.panasonic.com/industrial/includes/pdf/ACA4000CE189-CGA103450A.pdf
These are LiCo cells with 3.7v nominal and nominal capacity of 1950mAh.

Since the cells slowly drained down to 1.6v, I recommend you try to slowly charge them up and test if they still perform. Take extra care as they can be hazardous.

My personal experience with them is pretty good, I have successfully revived a couple dozen cells from 0.0v and still use them(I have about 30 cycles on them).
Capacity suffered a bit, I have measured about 1400 mAh from 4.1v and about 1600mAh from 4.2v @0.2C discharge.

If you want to use them in e-bike application make sure to size the battery well.
My pack is essentially 12S14P and I use it below 1C discharge rates and charge with less than 0.1C charge rate.

Cell picture: https://picasaweb.google.com/zsoltikocsis/Jul202011?authkey=Gv1sRgCI2cobbDx-rnbw#5631332978702665138
Battery pics: https://picasaweb.google.com/zsoltikocsis/Jul202011?authkey=Gv1sRgCI2cobbDx-rnbw#5631332909762346082
https://picasaweb.google.com/zsoltikocsis/Jul202011?authkey=Gv1sRgCI2cobbDx-rnbw#5631332823609446770