240,000μF capacitor vs dead lithium

[iamdarkyoshi]

"Don't forget health and safety..."

So I am managing to wake up some completely dead lithium cells by shocking them with two paralelled 120,000μF capacitors. Two of the 5 cells from a trash drill battery pack took a charge fine, the others wouldnt go over like 1.5v with a 100mA charge. After hitting them many times with the caps charged to 4.2v, they seem to be taking a charge now. The theory? When they were completely dead, they formed metal crystals inside that shorted them out, which is why my 100mA charge seemingly stopped. Hitting them with the capacitors vaporized the shorts. At least, thats the theory. Its a tried and true method with nicads, figured I had nothing to loose with these lithiums...

 

As you can see, its making its way past 2.36v, and as I type this, its now at 2.7v.

 

First off, before you guys go all health and safety on me, I do know what I am doing. For instance, the wooden platform I am charging it on and the lack of any fire extinguishers.

 

I do realize that they could all of the sudden become shorted inside again and explode, but oh well, I like fireworks.

 

@Hackentosher

 

[iamdarkyoshi]

10 minutes ago, AlexTheRose said:

But why?

Science.

[glengraegill]

awesome, great job man!

[QFA350]

This is the kind of stuff I like to see.

[failblox]

Interesting project, but I really recommend having at least a bucket of water nearby - and this is from my personal experience let's just say, experimenting with fire in my basement (yes, I was stupid). I got too close for comfort to burning my house down, and I would 10/10 would not do something like that again without having some contingency plan in case things go wrong. I realize a bucket of water might not be the best thing to extinguish an electronic fire with, but you get what I mean.

[iamdarkyoshi]

6 minutes ago, failblox said:

Interesting project, but I really recommend having at least a bucket of water nearby - and this is from my personal experience let's just say, experimenting with fire in my basement (yes, I was stupid). I got too close for comfort to burning my house down, and I would 10/10 would not do something like that again without having some contingency plan in case things go wrong. I realize a bucket of water might not be the best thing to extinguish an electronic fire with, but you get what I mean.

I have a garden hose about 10 ft away, close enough. This is at least in the garage.

[iamdarkyoshi]

Update. The other two cells are not as happy, couldnt get them to take a charge. So I upgraded my cap bank.

 

It seems that they are managing to blast the shorts out, but if I tap on the cell, I observed the voltage dropping quickly and certain areas of the cell getting hot. These are the shorts coming back. So I probably should try adding another 5 capacitors (I have nine) and using some short beefy cables. I will try again tomorrow. 

 

The original cell discussed here is now at 3.0v and is holding it. Not going to consider it "repaired" until I can get it to 4.2v and test it on my 1A discharge tester.

[Hackentosher]

Okay, interesting. About health and safety, a topic I find much pleasure in criticizing you on yet take little regard for it myself, why didn't you move this fireball-waiting-to-happen idk, 8 feet onto your driveway where there isn't a 400k house with your beloved younger brother and parents live to be burned up? 

[iamdarkyoshi]

6 minutes ago, Hackentosher said:

Okay, interesting. About health and safety, a topic I find much pleasure in criticizing you on yet take little regard for it myself, why didn't you move this fireball-waiting-to-happen idk, 8 feet onto your driveway where there isn't a 400k house with your beloved younger brother and parents live to be burned up? 

Although there is a risk of fire, I never leave this kind of crap overnight when I am not down there. It would take a whole lot of raw lithium to do any damage. Like I said, I have a garden hose right outside the garage door.

 

Also, look for the datasheet of a samsung cell.

Here is a snippit of their insane testing procedures:

Quote

8.1 Drop Test 
Test method: Cell(as of shipment or full charged) drop onto the oak-board 
(thickness: ≥ 30mm) from 1.5m height at a random direction 6 times. 
 Criteria: No leakage 
 
8.2 Vibration Test 
 Test method: Cell(as of shipment) is vibrated along 2 mutually 
 perpendicular axes with total excursion of 1.6mm and with 
 frequency cycling between 10Hz and 55Hz by 1Hz/min. 
Criteria: No leakage 
9. Safety 
 9.1 Overcharge Test 
 Test method: To charge the standard charged cell with 12V and 2.8A at 25℃ 
 for 2.5 hours. 
 Criteria: No fire, and no explosion. 
 9.2 External Short-circuit Test 
 Test method: To short-circuit the standard charged cell by connecting positive and 
 negative terminal by less than 50mΩ wire for 3hours. 
 Criteria: No fire, and no explosion. 
 9.3 Reverse Charge Test 
Test method: To charge the standard charged cell with charge current 2.8A 
By –12V for 2.5 hours. 
 Criteria: No fire, and no explosion. 
9.4 Heating Test 
 Test method: To heat up the standard charged cell at heating rate 5℃ per minute up to 130℃ and keep the cell in oven for 60 minutes. 
 Criteria: No fire, and no explosion.

I think I am far from these insane conditions. Granted, I am expiramenting with faulty cells, but like I said, the risk of any major damage is less likely than us having a decent president.

[klh2000]

I'm tempted to try this with a 1 Farad capacitor I have, but I don't have any dead lithium cells. I do however, have dead nicad cells.

[iamdarkyoshi]

1 hour ago, klh2000 said:

I'm tempted to try this with a 1 Farad capacitor I have, but I don't have any dead lithium cells. I do however, have dead nicad cells.

I have enough of these blue caps to get over 1F. I only have enough copper bus bars for four of the nine caps though.

[Hackentosher]

6 hours ago, iamdarkyoshi said:

I have enough of these blue caps to get over 1F. I only have enough copper bus bars for four of the nine caps though.

I won't be at all surprised if we see this type of stuff from Mr luke in a few weeks. 

 

 

[Huntsman]

This is actually a proven method, but only works up to certain point. Used to do this to my flooded lead acid but using inductor to store the charge instead of caps. You can look up pulse charging.