Tutorial: Laptop Battery Pack 18650 Extraction

[bshanahan14rulz]

DB: what's neat about laptop batteries, sometimes you can even pull data like how many cycles the cells have been through and when the pack was made from the laptop's battery "driver"

 

[RetroTechie]

1. measure cell voltage. if it's less than 2.5v, throw it away.

I'd question anything that depends on a momentary measurement to decide "good" or "bad". I can understand that a lithium cell (especially the common lithium-cobalt based chemistry) which has been discharged <2.5V and sitting there for a while, might be damaged beyond recovery. But that should not be decided by a simple voltage measurement.

IMHO it would be better to (try and) put a cell through at least 1 or more full charge/discharge cycles, and monitor how it behaves over time. If that behaviour shows far-out-of-normal parameters: discard. If that behavior shows far-below-nominal remaining capacity: discard. But if @ the start of the process it reads a much lower voltage than desired/expected: be patient, and see how it does further on.

 

[SilverFox]

Hello RetroTechie,

While your humble opinion is noted, let's take a look at this from a bigger perspective...

Laptop battery recovery is basically a free source of cells.

The most danger when using Li-Ion chemistry comes during charging.

Cells that have been over discharged have a higher probability of having "issues."

Most battery packs that are being salvaged have been sitting for a period of time allowing voltages to stabilize.

A voltage reading is a very good spot check of an over discharged condition.

If you have 6 cells and 4 of them read over 3 volts and the other 2 read under 2 volts, why not recycle the 2 low voltage ones and concentrate on the others?

Yes it may be possible to recover the other 2 cells, but is it worth the effort and piece of mind?

Tom

 

[flatline]

I'd question anything that depends on a momentary measurement to decide "good" or "bad". I can understand that a lithium cell (especially the common lithium-cobalt based chemistry) which has been discharged <2.5V and sitting there for a while, might be damaged beyond recovery. But that should not be decided by a simple voltage measurement.

IMHO it would be better to (try and) put a cell through at least 1 or more full charge/discharge cycles, and monitor how it behaves over time. If that behaviour shows far-out-of-normal parameters: discard. If that behavior shows far-below-nominal remaining capacity: discard. But if @ the start of the process it reads a much lower voltage than desired/expected: be patient, and see how it does further on.

I'm quite certain that I've thrown away cells that I could have probably used safely, but since I have no idea if a cell will cause trouble until after the fact, my guidelines for what cells to keep err very much on the side of caution. After all, I could save myself the trouble and simply spend $8 on-line for a new cell, so if a salvaged cell causes me any trouble at all, I would have been better off not salvaging it.

In the worst case, a salvaged cell that "vents with flame" in the charger could set fire to your house and endanger all within it. This is why I think that marginal cells are a poor gamble. Even with my cautious rules, I still usually keep about half of the cells that I pull out of laptops, although they're all gone now. Once the little man became interested in my flashlights, I locked up my 18650 lights and recycled all my salvaged cells. I can't watch him 100% of the time and it's just not worth the risk.

--flatline

 

[Petir]

How do I "calculate" the capacity of the cells? I have one battery pack for Fujitsu, it's written 10.8V, 4800 mAh, 6 cells.
Does each cells has 800 mAh?

 

[kosPap]

Well liIons are 4.2volt and 3.6V Nominal
3.6x3cells=10.8
4800/2cells=2400 mAh
so your battey has 3 cells wired in series (one behind the other)
and 2 sticks of these, wired parallel (side-by-side)

 

[funkychateau]

-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...

Good job!!:twothumbs

I used to do that when I first started recycling cells, but now I just leave a small square of the ribbon strap attached and burnish it smooth. Works great, much faster, and doesn't generate metal dust to get in the vent and other crevasses.

 

[RetroTechie]

Last week, harvested 8 cells from a ~12 year old (!) P3 laptop battery. A few tips:

1. Like stated earlier in this thread: separate cells starting with the bottom tabs first. Why? Cell wrapping is thin. When you puncture it, on the top there will be a short between case (negative) and positive pole. Read: rapid heating of the cell until you notice and remove the short. On the bottom, such a puncture won't do anything except damage the wrapping. Once cells are separated at the bottom side, it's easier/safer to cut tabs on the + side.
2. Use a non-conducting thingie like a toothpick to pull tabs a little up from the cell wrapping (into a "^" shape). That way cutting tabs is easier/safer and less likely to damage the wrapping.
3. When you cut wiring in the battery pack, take care what happens to those wire ends! For example tape them off until you separated all individual cells.

Didn't bother to take things outside, simply took my time and proceeded carefully to avoid "vent with flame" mishaps. Cell voltages were okay (~3.08V after sitting >6 months in the pack unused) and very consistent between cells. But obviously 12 year is a long time, and a laptop a harsh environment. So as expected their remaining capacity was very low (800~900 mAh) and I've found the cells unable to pull >2A loads. Probably will keep a few as spares / for testing purposes, but won't be of much use really. On the lookout for a more recent pack to pull 18650's from... 😉

Btw - if you use pliers to remove the tabs: I use pliers with a thin tip, and do this in a rolling motion (you wrap the tab around the pliers' tip). That way it's less likely to cause dents, micro-punctures or similar.

 

[Brewguy]

Hello everyone!

I stumbled across this thread the other day and it caught my interest. Here's why.

I use electronic cigarettes. Most of our "advanced" devices use anything from 18350 to 18650 batteries in them. Needless to say, the light bulb went on. I hopped on eBay and found a replacement battery for my laptop. Knowing that I rarely if ever use the battery on my laptop, I wasn't going to use my current battery for the experiment (never unplugged for any length of time), but would use the new one.

Got it today, opened it up and saw the 6 18650 batteries that I anticipated finding. Tested all of them with my multi-meter and they were all 3.92v. Not bad, 6 for 6.

But, the question that I have is, since these aren't labeled as anything more than 18650, I'm wondering on mah and brand to do more investigating as to whether or not these are going to be worthwhile to use.

Here is a picture of the battery:

Pulled from a battery pack for a Dell XPS M11530 laptop.

Can anyone point me in the right direction to figure out the mystery that are these batteries?

Thanks!

 

[Bullzeyebill]

Charge them up and see how they perform. Most Li-Ions are shipped with that voltage. Better for storage.

Bill

 

[Brewguy]

Charge them up and see how they perform. Most Li-Ions are shipped with that voltage. Better for storage.

Bill

What I'm "worried" about the most is amp limit and mah. While some of our devices have protection, most don't. They're just straight, what we call, mechanical mods. Button makes the connection and the devices starts "firing" the coil. I'm just wondering where I'm going to sit in regards to max amps permitted by these batteries. Which, is why I'm hoping someone can help identify them. Any search for "blue 18650 batteries" bring me a litany of Trustfire, Ultrafire, etc. For our purposes, we generally stay away from anything with the word "fire" in the name. 🙂

4 of them are on the Nitecore i4 intelicharger, and seem to be charging as they should. No noticable heat coming from them and the LEDs are flashing like normal. Have to see how it goes! 🙂

 

[Brewguy]

Alright. The charge went well. All batteries reached a full charge (4.27v).

Here's a little more information off of the battery pack, if it's helpful.

The laptop is a Dell XPS M1530.

"Rechargeable Li-ion Battery
TYPE TK330 1530
Rating: 11.1V DC (symbol) 5200mAh"

So, we've got 1733mAh batteries (as there were 3 parallel pairs). Does this help anyone?

 

[Mr Floppy]

So, we've got 1733mAh batteries (as there were 3 parallel pairs). Does this help anyone?

I think you have that wrong. It should be 3S2P for that battery pack of 6 cells. The cells should be 3.7V 2600mAh cells.

As for the electronic cigarettes, most of them are just a resistance coil. Use your multimeter and measure it, then you can apply Ohms law. For instance, 2.2 Ohms, I = V/R, I = 4.2/2.2, = 1.9A. So your fully charged cell has a max drain of about 0.8C. With old cells, I tend to avoid going over 1C.

 

[Brewguy]

I think you have that wrong. It should be 3S2P for that battery pack of 6 cells. The cells should be 3.7V 2600mAh cells.

As for the electronic cigarettes, most of them are just a resistance coil. Use your multimeter and measure it, then you can apply Ohms law. For instance, 2.2 Ohms, I = V/R, I = 4.2/2.2, = 1.9A. So your fully charged cell has a max drain of about 0.8C. With old cells, I tend to avoid going over 1C.

Could you help me out with the 3S2P? Am I interpreting correctly that you're saying 3 in series and 2 in parallel? Wouldn't that be 7 cells?

The reason I was thinking 3 parallel cells was due to the fact that all were connected the same and there were 3 wires running to the PCB (plus the ground). Not that I would complain about 2600mah cells rather than 1733, just trying to learn how you came to that conclusion.

In regards to the e-cigs, yep, everything I build goes on an ohm meter. If there's a question, I pull out the multi-meter to check. I'm a huge fan of keeping my hands and face in the same condition day to day. Hence why I'm trying to find out as much as I can about these batteries. 🙂 As it sits right now, I've been testing them using a protected device rather than a full mechanical so that if there is a short, I've at least got some (perceived) protection.

Thanks!

 

[Mr Floppy]

Could you help me out with the 3S2P? Am I interpreting correctly that you're saying 3 in series and 2 in parallel? Wouldn't that be 7 cells?

The reason I was thinking 3 parallel cells was due to the fact that all were connected the same and there were 3 wires running to the PCB (plus the ground). Not that I would complain about 2600mah cells rather than 1733, just trying to learn how you came to that conclusion.

3S2P means two parallel banks of 3 cells in series. http://img15.imageshack.us/img15/5479/3s2pultrafire18650prote.jpg

Maths, You have 6 cells, the individual cells will have to be either 3.6V or 3.7V. To get to 11.1V, 3 * 3.7 will get you that. The capacity of the pack is rated 5200mAh, the 3 remaining cells need to be in series as well in so the two banks will be in parallel. 5200 / 2 will give you 2600mAh .

The other factor is that no-one makes 18650 cells that are 1733mAh that I know of.

 

[Petir]

3S2P means two parallel banks of 3 cells in series. http://img15.imageshack.us/img15/5479/3s2pultrafire18650prote.jpg

Maths, You have 6 cells, the individual cells will have to be either 3.6V or 3.7V. To get to 11.1V, 3 * 3.7 will get you that. The capacity of the pack is rated 5200mAh, the 3 remaining cells need to be in series as well in so the two banks will be in parallel. 5200 / 2 will give you 2600mAh .

The other factor is that no-one makes 18650 cells that are 1733mAh that I know of.

Since there are 4 wires running to the PCB, perhaps it should be called 2P3S?
2 cells connected in parallel, then connect 3 of it in series.

I have a very limited knowledge on this, but I think the capacity calculation stays the same.

 

[Mr Floppy]

Since there are 4 wires running to the PCB, perhaps it should be called 2P3S?
2 cells connected in parallel, then connect 3 of it in series.

I have a very limited knowledge on this, but I think the capacity calculation stays the same.

Yes, it could be in that configuration and yes the voltage and amp hours are the same. Best follow the tabs and how they are connected but if you are cutting out the cells in pairs, then yes it probably is 2P3S, not that I know if there is a standardized way of representing parallel/series

 

[Brewguy]

Thank you all very much for the information. I've been using them in my general rotation of batteries and they've been performing very well. Their discharge is on par with my Panasonic NCR18650PD batteries that I've had for a couple of months.

Just a quick question, but does anyone happen to know which laptop battery packs are most likely to produce Sony cells? Not that I've found anything wrong with my mystery blue 18650 cells, but would kind of like to put a manufacturer with a battery so that I can find out what limitations I have with a particular cell.

Thanks!

 

[Mr Floppy]

Just a quick question, but does anyone happen to know which laptop battery packs are most likely to produce Sony cells?

Sony ones ..

For me, with the mystery cells I make sure that I don't draw more than 1C. I'm sure I've seen that logo on your cell somewhere but I don't remember where.

 

[Brewguy]

Sony ones ..

For me, with the mystery cells I make sure that I don't draw more than 1C. I'm sure I've seen that logo on your cell somewhere but I don't remember where.

Okay, you could have thrown a "duh" in there. I wouldn't have minded. Lol

I appreciate your restraint. Thanks again.