# Which laptop battery pack yields the best, highest capacity 18650's

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AlexGT
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Which laptop battery pack yields the best, highest capacity 18650's

I was wondering which laptop battery pack yields the best unprotected 18650’s, there is a recycle place close by where I can get a hold of a variety of used laptop battery packs for practically free, just want to know what to look for.

Any tips?

Edited by: AlexGT on 09/11/2012 - 18:30
ryanferg
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Well, you can use a little math to figure out what the capacity of the individual cells is. The battery will first have to be a lithium ion battery (of course). Most likely, they will be 11.1v, meaning that there are at least 3 cells in series (3.7*3). If the battery says 6-cell, then its 3 pairs of 18650’s in parallel, 9-cell means 3 sets of 3 18650’s in parallel.

So now, look at the capacity. If it’s measured in mah, then it’s pretty easy. Let’s take a 7200mah, 9 cell, battery (at 11.1v). This ends up being 21600 at 3.7v, and you have 9 cells, so you’re looking at 9 2400mah 18650 cells inside.

If the capacity is measured in watt-hours, then it’s basically the same thing. So a 9 cell, 84 watt/hour battery. Devide the watt/hours by the voltage(11.1) and you’ll get 7567mah.

Of course, the newer the better. Once you get the cells apart, make sure to test that they are above 3V or so using your DMM. Please seek out and read what others have written about determining what is a good vs a throw away cell from a reclaimed battery.

AlexGT
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Thanks for the tips Ryan! I have a Turnigy charger and will run capacity tests on the cells to find the good ones to keep. I was more interested in brands of battery packs like dell, sony etc. that members have opened up and found to carry name brand quality cells inside.

fccwpe64
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The Dells and Acers I have opened yielded 2050 and 2250 mAh panasonics which, for free, is great!

scaru
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Most name brand packs have name brand cells in. I have had good luck with dell batteries. They often have 2600 mah sanyo batteries in them.

apt323
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Thanks for starting this alex was just wondering the same thing
Posted on iphone

A number 1
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For example:

The Toshiba Qosmio x505 series uses a 12 cell 90 watt battery pack stuffed full of good Panasonic cells.

raccoon city
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I want to wish you a warm welcome to BLF, ryanferg!

willie
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I get HP, Dell, Acer,etc…… what ever is there. When I started out was checking every cell. Got to decide for yourself what parameters are acceptable, mine were skipping any cells that are not at least 2400ma original capacity and have at least 80%+ capacity. First thing is pull the big sticker off and removing the thin plastic covers. This is a major time saver as there is access to the cells (not all but most) with the least amount of effort as in busting open the pack. This allows identification of cells and DMM access to check voltage. From there toss them or proceed to dismantle, charging & checking. It’s not for everyone and kind of like fishing with good and bad days.

Chicago X
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A number 1 wrote:
For example: The Toshiba Qosmio x505 series uses a 12 cell 90 watt battery pack stuffed full of good Panasonic cells.

I'm typing this on a Qosmio x775 as we speak - it's good to know I could cannibalize her pack, if the SHTF.

Off-topic: the "brick" (charger) for this computer is literally a brick; it's the largest I've ever seen, period.  I guess it needs to be large, outputting 19V at up to 9.5A...

http://wardogsmakingithome.org/index.html

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mattthemuppet
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if you want to be selective, go for the ones most recently manufactured. Doesn’t matter what cells are inside if they’re dead, lost 1/2 their capacity or self-discharge like crazy. Or just take all of them, test all of them and take back all the duff ones. My hit rate is probably ~15%, with no rhyme or reason as to brand name packs vs. generic, brand name cells or plain wrappers.

As Mr. Gump said; “life’s like a box of chocolates”

willie
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mattthemuppet wrote:
if you want to be selective, go for the ones most recently manufactured. Doesn’t matter what cells are inside if they’re dead, lost 1/2 their capacity or self-discharge like crazy. Or just take all of them, test all of them and take back all the duff ones. My hit rate is probably ~15%, with no rhyme or reason as to brand name packs vs. generic, brand name cells or plain wrappers.

As Mr. Gump said; “life’s like a box of chocolates”

+1 About 1 in 8 for me. Had a run on good Samsung pink 2600s like 15 good cells like almost new capacity over a month period. Used 12 for a 4s3p HID pack. Been dry lately but haven’t been hitting the bins as hard. Have plenty for FL use at the moment.

dct73
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So just where is everyone finding these battery packs?

Manual Man
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I get mine from E recyclers, costs them money to recycle them so they give them to me free :bigsmile:

Obviously the newer the better however most battery packs I get are 2400 or 2600mAh cells. Dell and Lenovo packs yield the best I have found so far (Sanyo 2600mAh).

Battery manufactures I have found so far:

Samsung
Sony
LG
Sanyo
FHG (or something…. Chinese apparently)

From:

Dell
Lenovo
HP (mostly Sony 2600mA green (past it))
Acer
Toshiba

No Panasonic yet

mattthemuppet
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I get mine from recycling bins around campus or the workshop in the next building. I’ve found Panasonics before, in older Macbook batteries (‘05 ish), but almost all of them were toast or self-discharged. I have a couple that are decent.

So far I’ve never had a salvaged cell above 2Ah. Still useful, but if I need high capacity I’d rather buy new.

dno36
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ryanferg wrote:
Well, you can use a little math to figure out what the capacity of the individual cells is. The battery will first have to be a lithium ion battery (of course). Most likely, they will be 11.1v, meaning that there are at least 3 cells in series (3.7*3). If the battery says 6-cell, then its 3 pairs of 18650’s in parallel, 9-cell means 3 sets of 3 18650’s in parallel.

So now, look at the capacity. If it’s measured in mah, then it’s pretty easy. Let’s take a 7200mah, 9 cell, battery (at 11.1v). This ends up being 21600 at 3.7v, and you have 9 cells, so you’re looking at 9 2400mah 18650 cells inside.

If the capacity is measured in watt-hours, then it’s basically the same thing. So a 9 cell, 84 watt/hour battery. Devide the watt/hours by the voltage(11.1) and you’ll get 7567mah.

Of course, the newer the better. Once you get the cells apart, make sure to test that they are above 3V or so using your DMM. Please seek out and read what others have written about determining what is a good vs a throw away cell from a reclaimed battery.

OK RF,

I just pillaged a Laptop pack with 8 LG Salmon colored cells inside.
2 Cells low voltage = Recycled responsibly
6 Cells Good range charging now.
Pack states 14.8v & 4.4Ahr
14.8v/3.7v per battery = 4 × 4.4Ahr = 17.6 total Ahr / 8 batteries in pack = 2.2 mAh per battery??
Must be close, all the numbers came out even.
Now if I can figure a way to tell how much life is left in these, or any battery I have…….
Thanks for the help

The power of many minds working toward around a common passion.. & ..keeping the "B" in BLF

mattthemuppet
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it’s a bit simpler than that. If you have a 14.8V pack, you have 4 cells in series (4S). If you have 4 cells total in your pack, it’s 4 series 1 parallel (4S1P), so the pack Ah rating is that same as 1 cell (more cells in series = higher voltage, same Ah). If you have 8 cells, it means that they’re 4S2P. Doubling the cells in parallel (1P to 2P, for example) doubles the Ah of the pack. So if you know the Ah rating of the pack, divide it by two to get the capacity of the individual cells.

so, 4.4Ah pack in 4S2P = 4.4/2 = 2.2Ah per cell.

dno36
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You all make it sound soooo simple…lol.
Before cracking open the cases, I suppose we could estimate the number of cells and mAh of the batteries by numerical bracketing. This may help choosing the potential quality of the cells inside.

Thank For the help

The power of many minds working toward around a common passion.. & ..keeping the "B" in BLF

mattthemuppet
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yup. If it’s 14.8V it’s 4S, if it’s 11.1V it’s 3S. If the capacity is over 2.9Ah or so, then it’s 2P. Most laptop cells are 2.2 to 2.9Ah in capacity.

Speedsix
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I just salvaged 13 battery packs. I didn’t keep good track of which cells came from which pack because it seems really random. I had planned to note the name of the laptop and which cells I found in which packs.

I had 5-6 HP packs that were all very similar if not identical. Several must have been from the same model of laptop. After cracking them open, I found different cells in the packs. I expected to find pretty much all the same cells in the HP packs but it was not the case at all.

My point is, any advice about which cells are in which packs is going to be more a guideline than a hard and fast rule.

Probably the easiest way is just look at the pack. The bigger the pack, the more cells it probably contains. I had one large pack that contained 12 cells.

dno36
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From Post #15 in this thread, here is the pics of the slavaged cells.
Obviously they were LG cells, Korean specials. I was happy.

The batteries came apart without issue, peeling off the tabs as I went. There was a gum-rubber type sealer over the metal tabs which was peeled off as well.
These were flesh colored, not pink at all.
Then I found the ‘salmon’ colored reference and the pics matched, even though mine were a lesser 2200mAh capacity I was pretty happy with my treasure.
http://i997.photobucket.com/albums/af94/dno36/Flashlights%20and%20batter...
Better pic of removed pair:
http://i997.photobucket.com/albums/af94/dno36/Flashlights%20and%20batter...
Do these numbers have any reference values…LGDS218650??

So far 3 fully charged to 4.15- 4.17v. 3 more on charger.

I have another pack which may be “Quiz of the Day” material…
I bought this aftermarket to replace a dead pack. Shortly thereafter the computer crashed…off a wall to a ramp 9 feet below. I saved the pack in a small bit of wisdom.
There is NO numerical markings on this pack at all, aside from the model/SKU numbers.
Looks like it would hold about 5 pairs of 18650’s
http://i997.photobucket.com/albums/af94/dno36/Flashlights%20and%20batter...

Any guesses as to which batteries will be inside??

Cheers

The power of many minds working toward around a common passion.. & ..keeping the "B" in BLF

ObiWan-Kenobi
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I took apart a 6 cell from an MSI 17” gaming laptop (about 3 years old).
They were Samsung ICR18650-24E

I don’t have any measuring equipment, but they seem to go well in all my lights.

I posted another thread about a special on a Dell Inspiron 6 cell replacement for about \$18. Not sure whether to grab that deal.

dno36
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I spoke to a friend who works for ********, a major mobile phone company. He told me their company uses laptops by the thousands, and their in-house Tech team sends at least 10 battery packs a month off to recycling as they fail.
As I do work for them on occasion, I will ask them about the possibility of working out a deal where I would pick up their packs and recycle them.

The power of many minds working toward around a common passion.. & ..keeping the "B" in BLF

USSR
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to get  a maximum mah rating battery look for a battery bank that has highest wh ratings.

an individual cell having WH rating above 9.5 means it at least is 2500mAH.

now to get capacity of each cell look at below text of mine which i wanted to post at other thread but found this one relevant.

i got a way to calculate the exact theoratical capcity of the cell by just looking at the battery pack.

only three things are required and all are readily available.

1: Voltage of battery (most will be 11.1 or 10.8 v ) . this is written on battery.

2: Total Capacity (either in mAH or WH ) .. we need to do all calculations in Wh. if its given in mah then multiply the capacity in mah by the voltage of the pack.

3: Number of Cells -- one can judege them from the size of battery. (most will be 6,9,12 cell batteries)

Here is the its implementation

Dell    PC765    11.1V 5200Mah     LG LGDB118650    2600Mah    Post     Downlinx

total capacity in watt hour : 11.1 x 5.2 (remove the mili part by moving decimal over three points) = 57.72 WH

now since all cells are of equal charestristics so from battery appearance we can say its 6 cells so total capacity of each cell in watt hour (Wh) is 57.72/6 =  9.62 Wh

now to convert form wh to mah we divide the capacity in wh by voltage of that cell. Liion voltage are in 3.4-3.8 ranges. mostly .. so if its 6 cell battery and total voltage is 11.1 then we can say its 3 series and 2 parallel. we are concerned with series cells. so to get voltage of each cell divide total voltage of battery by 3 in above case 11.1/3=3.7

now we got voltage of individual cell so going back to our calculations .. we got capacity of each cell in wh ,, for mah divide wh/volts

9.62wh/3.7 volts = 2.6 Ah.

Second Example:

Fujitsu    FMVNBP135    7.2V 5200Mah    Sanyo Light Blue    2600Mah    Post     ChibiM

wh=7.2 x 5.2 =37.44

total cells assume 4

37.744 /4 = 9.36 Wh of each cell.

since 2 cells seems to be in parrallel to give 7.2 volts . so 7.2/2= 3.6

so mah of each cell

9.36/3.6 =2.6 Wh

Example 3:

Toshiba    PA3382U-1BAS    14.8V 6450mAh    Sony US18650GR    2150Mah    Post     Suncoaster

14.8 x 6.45 = 95.46 wh

seems 12 cell battery (4 series 3 parallel ) from look so 14.8/4= 3.7 volts to each cell

wh of each cell 95.46/12=7.95 wh of each cell

7.95wh/3.7v=2.15 AH

http://budgetlightforum.com/node/32720

i hope somone good at andorid programing would code a little utility for this purpose ... dang i never worked with visual programing. all were console based.

phiber
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I’m interested in changing the cells in my old Toshiba battery. The original battery went out and I replaced it with one bought in Bangkok.
Anybody interested in seeing photos from the original Toshiba battery and a “new” one made 4 years later?

Thanks for the calculations USSR

Junkman Jim
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This is my first posting. I read the whole tread, a lot of good info, thanks guys.
I have disassembled hundreds of laptop batteries, some from the local junk yard, others from auction sales,and some from friends and other sources. I bought 38 brand new Gateway batteries from a local source, I believe they were disposed of because they were the ones that caught on fire. I believe the problem was in the charging circuitry, the cells seem to be fine.
The cells were Sanyos they are pink, Sanyo cells are color coded, look at the positive end. White is 2000 mAh, red is 2200 mAh, green is 2400 mAh, blue is 2600 mAh, and purple is 2800 mAh.
I recently purchased a lot of laptop batteries, maybe 25, the ones yielding the highest capacity were Lenovos, I found two or three with 3000 mAh cells. The best part of this find was a large percentage of the batteries were almost fully charged.
I have been disassembling batteries for a number of years, the best method is the brute force method, grasp the battery firmly on one end, slam the corner on a hard surface then turn it and do the opposite corner, turn the battery end for end and repeat. It takes me about a minute to finish the job. Be careful not to hit the center of the battery, you might damage one of the cells.
Most of the lithium cells are rated at 3.6 or 3.7 volts, if they are charged to 4.2 volts it increases the capacity to almost double, this new batch seems to be happy at 4.2 volts.

Junkman Jim

flashination
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deathless
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What’s the best way to recycle the dead laptop pulled cells? Just drop them in a LOWES recycling bin (with the ends taped)?

202bigmike
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deathless wrote:
What’s the best way to recycle the dead laptop pulled cells? Just drop them in a LOWES recycling bin (with the ends taped)?

Just to name a few places that recycle batteries other then Lowe’s:
Home Depot , Radio Shack , Best Buy and maybe HH Gregg.
This is just some of the bigger name places , nationwide.

Mkduffer
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USSR wrote:

since 2 cells seems to be in parrallel to give 7.2 volts . so 7.2/2= 3.6

so mah of each cell

9.36/3.6 =2.6 Wh

Batteries in parallel (positive to positive, negative to negative) multiply current (amps), voltage remains at single cell voltage.
Batteries in series (positive to negative) multiply voltage while current remains the same.
Wattage (power) is volts X amps
Capacity is either Ah (Amp Hour) or vAh (VoltAmpHour, also watt hour (Wh (or KWh on your electric bill)). The difference between watt hour and volt amp hour is something called “power factor” which doesn’t apply in DC applications since voltage and amperage are never out of phase.

Hope I’m not stating the obvious here, but I’ve seen several posts which could be easily answered with basic knowledge about electricity but not a lot that elaborate on the basics, so here we go.

A common analogy for electricity is water flow. A bucket can serve as our battery.

• Volts is a measure of potential, the difference between the poles(terminals). A bucket of water at ground level has no potential. If you elevate it, now it has potential. The higher you elevate it, the more potential it has.
• Amperes (Amps) measure current flow, coulombs per second. A coulomb is a fixed quantity of universal charge units. If it makes it easier, consider coulombs a fixed quantity of electrons. A bucket with no hole in it has no flow rate. Add a hole and you create flow and can then measure flow rate (water leaving over time). Bigger hole, larger flow rate. High drain devices (those which require a lot of current over a short period of time) like certain vaping devices and high output lights can deliver their maximum potential when paired with power sources that can deliver current to match the device’s needs.
• Amp-hour (Ah or mAh (milliAmpHr = Ah/1000)) measures how much coulombs the cell can deliver. In the water analogy, how much water the bucket can hold. Remember, Amps = coulombs/hour so if we multiply that by time, we cancel out the units above and below and are left with coulombs, which in our water analogy is equal to the volume of water in the bucket.
• You need both voltage and current flow to have power (Watts or VoltAmps). A full bucket at ground level can deliver no water. Likewise, a bucket lifted way up in the air with no hold also can not deliver water. Also, an empty bucket high up in the air also has virtually no available energy. An example of this is a Tesla coil.

The reason manufacturers use differing voltage/current combinations has to do with things like conductivity, losses, etc… Trying to push a lot of current through a small wire (or circuit) will generate a lot of heat, which is detrimental to the circuit and also generates a lot of heat, which wastes energy.

Back to battery packs. Part of the problem is that manufacturers sometimes use different voltages to calculate the voltage of their packs. The pack voltage is a multiple of the base cell voltage that they use. Some use 4.2v, 4.0v, 3.7v and others 3.6v. The first thing I do is look at the voltage rating of the pack and try to determine which base voltage they are using. If the pack voltage is 4, 8, 12, then they are probably using 4,0 volts in their calculations. 4.2, 8.4, etc.. and I’d assume 4.2. 3.6, 7.2, 10.8, etc…3.6 and 3.7, 7.4, 11.1, etc.. 3.7.

I also look at how many 18650’s would fit within the form factor. BTW, most modern battery packs are comprised of multiple unprotected 18650’s, but I have seen other battery types, so this is not an absolute. I’m currently looking at a battery pack from an Acer Netbook. The battery compartment is approximately 8” long and 1 5/8” wide (same as an HP laptop battery pack I’m also looking at). Converting that to metric, we get 203.2mm x 41.275mm. The nominal dimensions of an 18650 is 18.6mm diameter x 65.2mm len. Based on that, we see that we can fit 2 rows of batteries 3 high within this space (2 × 18.6mm = 39.2mm (well within 41.275), 3 × 65.2 = 195.6 (also well within 203.2mm)). Based on this, we can surmise that the pack has 6 18650 cells within.

Both the Acer and HP list their pack voltage as 10.8v, so they are using a combination of batteries in parallel and series. Since 10.8v = 3 × 3.6v, we can determine that the pack has 3 pairs of batteries, each pair comprised of 2 18650 welded (not soldered, btw) in parallel, with the 3 pairs connected in series.

The specs on the outside of the Acer pack says 10.8vdc, 4400mAh, 48Wh. From above, we know that batteries in series multiply voltage, so if we divide 10.8 by 3, we confirm Acer is using 3.6v in their calculations. Also from above, we know that batteries wired in parallel multiply capacity and since ours are in pair we can divide 4400mAh and determine that our individual cells are probably speced at around 2200mHh.

The HP specs are 10.8v, 55Wh. Dividing 55Wh by 10.8v results in 5.10Ah per cell, but don’t forget, their “cell” is actually 2 18650’s welded together in series, so to know the Ah of each 18650, we need to again divide 5.10Ah by 2 18650s so the final result is 2.55Ah per 18650.

Based on the above calculations, we can assume that in this case, the HP pack uses higher capacity 18650s, which makes sense, as it is a newer pack and I’m assuming 2550mAH batteries either didn’t exist when the Acer pack was made or they used lower capacity because of cost or other design considerations (probably the latter).

People say I’m a flashaholic like it’s a bad thing…

jhalb
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Try one of these packs if you like LG 4.35 volt cells. These cells willingly made available 2989mAh of power from 4.35 to 3.0 volts on my Opus BT-C3400 Ver. 2.1.

I love these cells!

Has to be that exact type and sticker though, Genuine Dell only.

Ebay item number: 121538052911

He has 2, I bought one. There's one left but his price almost doubled. I payed \$30 in my offer. There are other sellers that have them too.