[jockepocke]

I found a 40 AH thundersky (TS-LPF40AHA) cell that I bough with a resting voltage of 0,04 V, so it wont be used in the battery pack for my car. It is charging right now at 3,6 V, 2,6 A (voltage limited), and begun charging at 3 A at 1,1 V (current limited).

So I have a battery to play with! Anyone has a test to request that I can do at home? Would like the battery to be of some use!

UPDATE: ok, cell is behaving strange... now charging at 3,3 A at 3,6 volt, current limited. charging current has been increasing as well as decreasing, changing from current limited to voltage limited and back again a couple of times... Not expecting super performance from this cell!

 

[steven4601]

Good grief, resting voltage of 0.04? AFAIK from my Li-Ion,LIPO battery experience, that battery is RIP. Im interrested how many amps it will take and hold over time .

I found a 40 AH thundersky (TS-LPF40AHA) cell that I bough with a resting voltage of 0,04 V, so it wont be used in the battery pack for my car. It is charging right now at 3,6 V, 2,6 A (voltage limited), and begun charging at 3 A at 1,1 V (current limited).

So I have a battery to play with! Anyone has a test to request that I can do at home? Would like the battery to be of some use!

UPDATE: ok, cell is behaving strange... now charging at 3,3 A at 3,6 volt, current limited. charging current has been increasing as well as decreasing, changing from current limited to voltage limited and back again a couple of times... Not expecting super performance from this cell!

 

[EVfun]

My request for a first test. After charging and verifying 4 hours later the cell is 3.3 volts or greater measure the terminal voltage every day for about a week. I suspect the cell will go dead on its own. This seems to be one of the failure modes of Li cells but I have no idea how fast it happens. Of course, if your cell holds a charge it may prove to be useful for learning about Li behavior.

 

[jockepocke]

Continuing charging now, after having a nice new year!

Going to try and charge it full, and see self-discharge as suggested! Will try and determine how much energy it can hold too, later. Might learn something about how much abuse these cells can take!

Right now charging at 3,6 v and with 3 A, voltage limited again... At what amperage is the cell considered full? Heard it should be something like C/100?

Any suggestions on why it went dead? I am suspecting anything from short-circuit during transport to some kind of internal chemical fault...

 

[GerhardRP]

Have you tracked [integrated] the ampere-hrs absorbed so far? That would be interesting.
Gerhard

Continuing charging now, after having a nice new year!

Going to try and charge it full, and see self-discharge as suggested! Will try and determine how much energy it can hold too, later. Might learn something about how much abuse these cells can take!

Right now charging at 3,6 v and with 3 A, voltage limited again... At what amperage is the cell considered full? Heard it should be something like C/100?

Any suggestions on why it went dead? I am suspecting anything from short-circuit during transport to some kind of internal chemical fault...

 

[jockepocke]

Have you tracked [integrated] the ampere-hrs absorbed so far? That would be interesting.
Gerhard

Nope, sorry, I though so too, but too late now... I would estimate by time*current about 20 AH.

 

[jockepocke]

OK, I just stopped charging at 3,6V, 0,4A. Cell is resting at 3,56V. Oops, now 3,55, EDIT now 3,54 - slowly but steadily decreasing.

Guestimation is that it took a bit more than 30 AH, but a bit less than 40AH.


Another EDIT: Now 3,4 V resting.

 

[jockepocke]

Update:

T+ 3H 30 min and voltage has decreased from 3,4 to 3,36.

Noted a slight swelling - this battery wont be usable for long... Apparently, stacking 6 batteries on top had been enough to keep the battery flat while charging, but once free, it swells about a mm or so, hard to see, but distinguished if you put it on a flat surface!

How prone to swelling are the thundersky cells? Also, I need recommendations for my battery wrapping! Mow how much force must it handle?

 

[EVfun]

Update:
T+ 3H 30 min and voltage has decreased from 3,4 to 3,36.

Noted a slight swelling - this battery wont be usable for long... Apparently, stacking 6 batteries on top had been enough to keep the battery flat while charging, but once free, it swells about a mm or so, hard to see, but distinguished if you put it on a flat surface!

How prone to swelling are the thundersky cells? Also, I need recommendations for my battery wrapping! Mow how much force must it handle?

Interesting how fast the voltage is slipping. I find it takes at least a day to get back down to 3.36, which is what I find to be the fully charged and rested voltage.

I can't really comment on how much force is needed, I have mine banded with 8 stainless steel straps between aluminum end plates (the system they are shipped with, but rows of 8.) My understanding is that swelling is associated with an increase in internal resistance. I've seen pictures of cells swollen quite a bit more than 1mm. It is interesting how little force you where using to keep it flat.

 

[jockepocke]

Interesting how fast the voltage is slipping. I find it takes at least a day to get back down to 3.36, which is what I find to be the fully charged and rested voltage.

I can't really comment on how much force is needed, I have mine banded with 8 stainless steel straps between aluminum end plates (the system they are shipped with, but rows of 8.) My understanding is that swelling is associated with an increase in internal resistance. I've seen pictures of cells swollen quite a bit more than 1mm. It is interesting how little force you where using to keep it flat.

It down to 3,35 now! I put it back under the batteries, so it is flat. Don't think there is much capacity here. I was planning on using iron bars, iron/alu sheets and strapping big sets with treaded rod.

I have read a bit on the forum, and it seems like swelling only occur when overcharging, or the battery is faulty? I need to balance my batteries, by putting them in parallel, they are not fully charged now, most of them rest at 3,28 v, so none should be fully charged if they are paralleled. Can I parallel them without strapping?

 

[Coulomb]

Right now charging at 3,6 v and with 3 A, voltage limited again...

My limited experience is with 40 Ah CALB/Sky Energy cells, which may be a little different. With a good CALB cell @ 3.6 V and 3 A, the voltage would be rocketing up (0.1 V every few seconds).

At what amperage is the cell considered full? Heard it should be something like C/100?

I've heard C/20, though a good cell should taper off to something like C/1000 at constant voltage.

Any suggestions on why it went dead? I am suspecting anything from short-circuit during transport to some kind of internal chemical fault...

So presumably it's had no ill treatment; it came out of the box (or perhaps off the shelf/floor) at very low voltage?

My guess would be failure (through punctuation or weak spot or the like) of the insulating layer at some point, causing a partial short circuit. That would cause rapid self discharge, and would cause the cell to self-discharge quite quickly. These cells are basically made of layers; one of them is an insulating layer, and that's the one I'd suspect has failed.

 

[Coulomb]

I have read a bit on the forum, and it seems like swelling only occur when overcharging, or the battery is faulty?

I think they're not supposed to swell with normal charging, but I've seen them swell with very gentle charging. So I've gotten into the habit of clamping all cells before they get charged at all.

 

[jockepocke]

Ok, thanks for the info! Don't wanna risk these amazing energy boxes!

First time I measured voltage it showed 0,04 V, yes. I have not dropped any of them etc. Only thing I can think of is that I transported them inside my apartment complex in small plastic-covered "shopping" cart, but put them so the poles could not touch anything, and did not notice anything either. They were all transported together, but the company said they had measured them all!

UPDATE: Now after the night, cell is resting at 3,34 V.