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Tutorial: Laptop Battery Pack 18650 Extraction

csshih

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Hey all,I thought this little tutorial might be useful for some of you out there

Disclaimer: Please note that you are taking apart battery packs in this tutorial which is expressly discouraged by the manufacturer as this is potentially a very hazardous process. I cannot be held responsible for any loss of property, damage, or loss of life if it comes to that. This tutorial was written for the highly educated users of rechargeable lithium ion technology, please do not attempt this if you are hesitant or unknowledgeable about these risks. Stay Safe.


Please read all the tips these CPF members have given! :

https://www.candlepowerforums.com/posts/3138913&postcount=7
https://www.candlepowerforums.com/posts/3138924&postcount=8

Here's a little tutorial on how to harvest those 18650s on whatever old laptop battery pack you might be tossing out. Most of the time, laptop battery packs go bad when just a few cells in the pack are dead. the protection circuit cuts out the entire pack as a necessary protective measure for the user. There are still a few good cells though.

Please check which batteries are good though checking how well the cell can discharge(as most old ones develop high interenal resistance), and how long the cell can keep its charge.

note: the cells you extract are not button top.

IMG_0255-800.jpg

We start out with 4 innocent looking extended life lenovo/IBM battery packs

IMG_0260-800.jpg

find the weak spot somewhere along the seams, and pry until the pack pops open. the packs are usually ultrasonic welded along the seams, with added double sided tape.

IMG_0262-800.jpg

continue prying.. these cells are held together with some sort of adhesive and snap-on tabs, too.

IMG_0264-800.jpg

here is a single pack open.

IMG_0268-800.jpg

repeat.

IMG_0270-800.jpg

pull the cell assembly out of the pack.. they are normally held in by double sided tape.
Be very careful when removing the cell assembly.. try not to bend the tabs as they could meet and short, resulting in a fire or explosion. (if left shorted)

IMG_0271-800.jpg

cut the weakest link, and separate the cells carefully.

IMG_0272-800.jpg

remove the protection circuit, being very careful not to short out anything.. avoid contacting 2 separate metal pieces if you are unsure about polarity.

IMG_0273-800.jpg

keep all the tabs separate. While doing this I accidentally touched 2 tabs onto another tab, giving me a big ol' spark and heatup of those cells.

IMG_0274-800.jpg

separate the cells from each other.

IMG_0275-800.jpg

repeat.

IMG_0278-800.jpg

separate the cell pairs.. first remove the bottom tabs, then work on the top

IMG_0279-800.jpg

be very careful at the top.. shorting out the pack can be caused by just punching through the thin shrink wrap.

IMG_0282-800.jpg

twist the solder tabs off with pliers.

IMG_0289-800.jpg

:)

IMG_0291-800.jpg

and there you have it, a mass collection of 18650s!
 
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Crenshaw

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Singapore
Nice....Might do this when i get home....

And thats a WHOLE lot of 18650s....

and look at that smiley face...:)


Crenshaw
 

csshih

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San Jose, CA
nope, download,

a fellow CPF member rescued these packs from the junk pile for me. I don't have a laptop that works with them.

I pretty much junked the plastic shells getting them open anyways..

heh, smileyface.
 

vudoo

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This is awesome! :D

Now to hunt around for some unused laptop battery packs. Whats a good way to check if the cells are still "good"? Charge and see if they hold the volts and then see how long they last for?
 

Fallingwater

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Trieste, Italy
Some additions:

- when doing anything with bare liion cells, it's wise to have a fireproof container nearby, along with a bucket of sand. If a cell starts heating up and/or smoking, quickly throw it in the container and dump the sand on it. Sand is the only reliable way of dealing with a lithium fire; water and most fire extinguishers won't do squat. I'm told fine kitty litter might work in place of sand.

- if having trouble finding a weak spot along the seams, use a dremel saw or cutting disk to cut through an angle - not along the seams, or you risk damaging cells. Then insert a large flatbladed screwdriver in the cut, twist, and the pack should start coming apart.

- if you want to build a pack with the harvested cells, you might want to keep the tabs instead of twisting them off, as it makes soldering a lot easier and safer. On the other hand, if you don't want to build a pack, then twisting them off is mandatory, or they'll cause shorts when put in battery tubes.
 

flatline

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Here's the recipe I use to determine which cells are healthy enough to be usable. If any of you see something that could be improved, please let me know (I think I'm probably being too conservative, but don't really know for sure).

1. measure cell voltage. if it's less than 2.5v, throw it away.
2. charge the cell. if it gets hot during charging, throw it away.
3. measure cell voltage off the charger. verify it's between 4.1 and 4.2v.
4. wait 30 minutes
5. measure cell voltage. if it's fallen less than 4v, throw it away. Otherwise record the voltage.
6. store cell for 3+ days in cool, dry place.
7. measure cell voltage. if cell voltage has fallen more than .1v from the recorded voltage, throw it away.

Any cell that hasn't been thrown away by the time I'm through with step 7, I keep and put into my regular cell rotation.

EDIT: I'm no authority, but since nobody tried to correct me, I'm willing to assume that there's nothing obviously wrong with the above recipe.

--flatline
 
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Search

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The tenth picture, the very top right battery. It says USA. I didn't think they made 18650s in the USA. I'm guessing it's not made in the USA.
 

kramer5150

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Palo Alto, CA
Nice tutorial!! Congrats on not lighting your house on fire!!

I do believe Lenovo uses Sanyo cells. FWIW, in my SF-6P with MC-E drop in these cells deliver 2.3A while AW IMR delivers 2.65A. In my P7 light (which I am intentionally under-driving) these sanyo cells deliver 1.65A, while an AW IMR pumps out 1.85A. These are all average measurements from two IMR and 6 Sanyo cells. Measurements taken at the tailcap.

I have pulled apart probably 10 packs and have found pink cells from Samsung, green and blues from Sony, and Panasonics of all different colors. So far these red Sanyos are by far the best performing, from a current output standpoint. I am not sure what their capacity is, but I would guess its around 1800-2000 mah (?).

So these particular cells, while not the absolute best, are certainly serviceable.

Couple tips I have picked up along the way..
-I do this kind of DIY work outside, on my brick patio. That way if there is a fire I just let them burn, and stand by with a hose. I still exercise caution though. One time I was rescuing some cells and I accidentally shorted some wires which started to SMOKE and glow orange. The pack lit up and I threw the flaming pack into the bathtub before the cells vented, and covered it with a wet towel. That was too close for comfort!!

I make sure I use tools that are blunt and smooth ALL OVER. Even the back sides of cutters and pliers. One time I shorted out a cell with my wire cutter. I was cutting a +ive wire and the back side of my wire cutters scraped through the heat shrink, shorting -ive to +ive. It melted a metal spot on my tool.

-Once I free the cells I measure each one. Any cell that measures below ~3.25V gets tossed. I usually end up tossing 2-3 cells out of each group of 9.

-If you wanted to meet up, just PM me. I can dremel off the weld spots from the ends for you. Those little spots on the ends of the cell will chew up your light. Your light collection is $$$$$, and its worth the added effort. Heres what mine look like after dremeling...
dscn2100.jpg

dscn2099a.jpg


Good job!!:twothumbs
 

rizky_p

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Nice guide. Those look exactly like Sanyo cells, probably they are. Good performance, DD my MCE light @2.4-2.5A. I bought them as loose cells cost 7USD each.

I tested 2 Sanyo cells @2A discharge came up close to 2400mah. the seller said it is Sanyo 2000. probably Sanyo state the min capacity.

Sanyo18650discharge.jpg
 
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csshih

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The tenth picture, the very top right battery. It says USA. I didn't think they made 18650s in the USA. I'm guessing it's not made in the USA.

actually, it says "L18A".. close.. :oops:
thank you for the offer kramer ;) . I should be fine at the moment.
 

^Gurthang

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Very nice tutorial, well written and good pics. I've harvested LOTS of cells from some Dell laptop packs and the best part [besides the cells] is the packs make excellent carry cases.

Dell cases are 6 cell rectangular packs, just carefully pry open from the connector end until the case separates. Extract the cell pack by the PCB end first, clip the PCB connections then separate the cells as CSSHIH demonstrates.
 

bshanahan14rulz

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I've noticed that many battery packs come with the Texas Instruments charging and monitoring chipsets (bq29330 cell protection, bq20z70P monitoring chip for the one I'm holding right now). What's the potential for turning this charger PCB into a 4-cell balancing charger? There are 6 pins connected to the pcb that go to the computer, but only 5 are labeled: P+, P-, T, C, and D. A lot of it is silk-screened, so kinda hard to reverse-construct the circuit. Do you think it may be just as easy as powering the P+ and P- pins? I could care less about the monitoring of the cells, but I would like for it to charge correctly though. But if we can figure out a cheap way to make a 4-cell charger out of the battery packs, we could save quite a bit on balancing hobby chargers.

BTW, my lenovo packs have sanyo cells, HP pack(mfd. 2007) had samsung 2200mAh. macbook had sony li-poly flats

Edit: opened a new MBP pack, contains 6 2820mAh Sanyo LiPoly flats. PN: UPF644496M. charging current: 1.8A! Uses bq29312apw and bq 20Z80A for cell protection and cell monitoring. Cells look to have been made jan. 08. Will keep them in pairs, too much tape to take the 3 pairs apart.
 
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csshih

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sorry for not noticing your post..
indeed, macs now use lipo cells.. so no 18650s :(
(but they do have good cap as more space in the battery pack is actually used)

I have no idea about the charging circuit idea. perhaps someone more educated could chime in.
 

alfreddajero

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Hey buddy im glad you posted this up.....me and the wife were cleaning up the spare bedroom to find her old Dell lappy.....and going through this thread last night i was like why not.....i of course asked her for permission and she gave me the go ahead. I had my asian buddy Craig call me up and asked about the voltage per cell and what they should be, he said that all 8cells were fine.....at this moment i have four cells charging up.....this is a great way to save money.

p1060012.jpg
 

csshih

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Mik

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I recently saw this thread, and starting asking people I know if they have any Li-Ion laptop batteries that they would like to get rid of. Lots of people had them, so now I have a bundle of incoming packs to take apart soon. Thanks for all the info in this thread. I am hoping that I get a few good ones!
 
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