Tutorial: Laptop Battery Pack 18650 Extraction

[mummel]

I had no idea laptop batteries had these in them. This is great. Thanks.

 

[fallingshad0wz]

can somebody help me i am using an older multimeter to measure the voltage of my 18650 batteries. I have it set to 10 DC Voltage. The weird thing is, is that there are coming up as 5.8 volts, almost 6 volts. Is this because they are not being used like not being drawn power from and just sitting there or is there something I am doing wrong with the multimeter.

 

[fallingshad0wz]

it gets even weirder or maybe not so wierd and just common sense. I just measured the batteries(the samsung ones from my laptop battery pack) I posted about 20 posts back. They all read just around 4 volts while my Chinese made ultrafire (who knows what they really are or what brand) were measuring a about 6 volts at a full charge what the heck is Ultrafire always like this I would think that they had lower voltage not higher

 

[HKJ]

Try replacing the battery in the meter.

 

[fallingshad0wz]

Try replacing the battery in the meter.

already did and calibrated it

 

[NeilP]

The weird thing is, is that there are coming up as 5.8 volts, almost 6 volts. Is this because they are not being used like not being drawn power from and just sitting there

No, resting , open circuit voltage should still not be more than 4.2 volts.

or is there something I am doing wrong with the multimeter.

Possible but unlikely.
If you have fresh battery, DC Volt range and leads plugged in to meter correctly there is nothing to do wrong.
You say older meter, how old? Is it digital display or moving coil with a needle ?





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[NeilP]

Did they all get charged in the same charger?




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[fallingshad0wz]

No, resting , open circuit voltage should still not be more than 4.2 volts.




Possible but unlikely.
If you have fresh battery, DC Volt range and leads plugged in to meter correctly there is nothing to do wrong.
You say older meter, how old? Is it digital display or moving coil with a needle ?





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I am using one with a moving coil and needle

 

[fallingshad0wz]

No, resting , open circuit voltage should still not be more than 4.2 volts.




Possible but unlikely.
If you have fresh battery, DC Volt range and leads plugged in to meter correctly there is nothing to do wrong.
You say older meter, how old? Is it digital display or moving coil with a needle ?





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It's pretty old like idk how old but it'd old

 

[NeilP]

'Old is relative to how old you are' ..I 'd say a meter that is 15 years old and digital is fairly modern,

So if it is moving coil ,it could well be a mechanical problem. I could see that an older meter with a lower resistance cold potentially give a lower voltage reading due to the IR of the meter, but not a higher voltage
getting meter set wrong is a possibility.

just had a very similar conversation with a bloke with the username scoot-e over on the e-bike forums...He was getting 110volts out of a 50 volt Lipo charger..till he realised he was using his meter incorrectly.

i'd nip down to you local Halfords/RadioShack/harbour Freight /etc and pick up a cheap $5 meter and try again.

 

[jtgr94]

Hey all!

I figured I'd join this forum, you guys seem to know a fair bit about batteries. I know a fair bit too, so I think we'll get along.

I dissected my old laptop battery, found some Sony GRs.

I doubt I'll ever have any use for them, given they appear to be maybe 1A?
Using Sony's date code method, I do believe they were made in 2004, at plant E, on the 14th day. I would be pushing it to assume that they have a 10A Max.

Oh well, time to steal neighbors laptop battery packs.

Have a good day ladies 'n' gents!

 

[xzel87]

Question, how hot/warm is considered too hot when charging up a salvaged cell?, I'm using an xtar mc2 and based on HKJ review the charger does get warm and will warm up batteries to some extent.

I've salvaged 3 packs, one pack gets considerably warm when charging and getting close to the 4V mark. The other pack gets warm as well when reaching 4V mark. these 2 packs had cells that measure between 2.8V and 3.4V. The third pack had cells measuring between 3.6V to 3.8V, and this set stays cool throughout the charging period. Does this mean that the internal resistance of batteries is high if it gets warm during charging?

The 3 packs contains cells from Panasonic, Sanyo & Sony in the order described above.

 

[SilverFox]

Hello Xzel87,

As cells age they warm up during charging. I prefer cells to remain cool and think you may be taking some additional risk when a cell heats up.

In absolute terms, "too hot" is when the cell vents. Usually the cell is too hot to hold in your hand just prior to this.

If the cells are free, why take chances? Just use the cells that stay cool and move on. On the other hand if you are curious you can continue to use those cells and set up a charging area that can handle a rapid venting with flame incident. Unfortunately as cells degrade they are less predictable. Just because 1 cell behaves in a certain way near the end of life doesn't mean the next cell (or brand) will behave the same way.

The other thing to keep in mind is that the cells that are warming up probably aren't providing the same performance as the others. Depending upon your application this degradation in performance may or may not be observed but rigorous testing should show a difference.

Tom

 

[NeilP]

Not scientific, but when dealing with ANY lithium chemistry, I reckon if it is too hot to grab and hold for an extended period, then it is too hot..otherwise, it is fine.

Cooler the better, but if you can hold it then I'd not worry too much.

 

[NeilP]

Looks like we cross posted

Hello Xzel87,
As cells age they warm up during charging. I prefer cells to remain cool and think you may be taking some additional risk when a cell heats up.

True


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In absolute terms, "too hot" is when the cell vents. Usually the cell is too hot to hold in your hand just prior to this.

Yep.





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If the cells are free, why take chances? Just use the cells that stay cool and move on.

this is where I disagree...😉 I'd say take the chance.......but only if you can isolate the charger from the cell via jump leads and your cells are in a safe fire proof place, or you don't mind potentially sacrificing a charger and it is in a fire proof place.

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on the other hand if you are curious you can continue to use those cells and set up a charging area that can handle a rapid venting with flame incident.

Now you're talking!!

I've tested many to destruction, it is surprising how much abuse they can take before you can get them to blow.

take a look here.

This is with a far more volatile cell, a 5Ah individual LiPo cell pouch/

Sorry about the poor quality of the video, but you will get the idea of the abuse they can take before they blow. They are nasty things when they blow, but it is actually surprisingly difficult to get that to happen





https://www.youtube.com/watch?v=9FRjFxKoUYQ

 

[xzel87]

Thanks for the input Tom and Neil.

I suppose I should err on the side of caution.

Will retest the voltages (3 day period) and I'll see what to do with them by them. If the 3rd pack of 6 cells is good was planning to use them in my w502 with a spare to be used in the car. The remaining 4 will be stored as backup battery for the light and/or powerbank (ML-102/Ruinovo 4 Cell). Basically these cells will not be involved in any Primary/Important roles, just as backups.

Since I don't have a discharger, will have to use flashlight current draw to estimate capacity. Unfortunately the w502 hasn't arrived yet for that purpose so I'm sitting on my hands at the moment.

For the other cells that warm up while charging, may use them for lantern duty or for very low power draw situations since I expect their capacity to be greatly diminished.

 

[NeilP]

For a cheap build to test cells search e-bay

This looks too high voltage for a single cell, but there are many others that log Ah and show voltage.

http://pages.ebay.com/link/?nav=item.view&alt=web&id=181626529280

Connect up a cell, via one of these, and a bulb, a 12 volt car bulb will do. No idea what wattage you will need or how many either in series to decrease current, or in parallel to increase current.

Just select a bulb or three to give whatever discharge current you think appropriate.

Then let it run, keeping an eye on the voltage so it does not dip below a safe lit, certainly now lower than 2.5 volt.




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[xzel87]

Hi Neil, I own a C-9000 charger and was hoping for something similar with li-ion, really don't want to mess with cables and clips and whatnot if I can help it. Wife is already giving me the "look" when I bought the multimeter, but oh well, I convinced her it's useful not just for batteries.

Anyway, finally retested the V of some of the charged up salvaged cells, final pack (the one that was cool during charging) will be tested tomorrow but I quickly tested one cell and it only dropped by 0.01V, so looking good there. Can't say the same for the rest though.

1st pack
https://www.dropbox.com/s/ipkp0hnm4d5ta6q/Panasonic (DELL).jpg?dl=0

Seems like all are not good.


2nd pack
https://www.dropbox.com/s/1vnlnvxc5fy4dh7/Sanyo (Acer).jpg?dl=0

with the exception of 2 cells, the other 4 seem like goners to me.

 

[NeilP]

I see the cells are in blocks. Are they actually electrically connected ? or just packaged like that by yourself for convenience and insulated. Looks like I can see tape but just checking

You would not need to have a messy wired filled table to use that meter. You could get constructive and build it in to a box with a single cell holder and a power resistor for the load.
(RWF) RW23-1.51.5 ohm5%68wWire Wound Resistor
https://www.surplussales.com/Resistors/WireWound/WW101-299.html


You could get fancy and add switchable resistors for varying loads.





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[xzel87]

I packaged them that way, original battery case was totaled when I was prying it open. I then tape up both ends with electrical tape.

I did think of that, but unfortunately my skills with tools are rather horrible when it comes to building things from scratch thats why I'd rather stick to pre-made items/products.

On another note, I'm looking at a few hobby chargers now with discharge function, seems pretty well packaged, just not in the form and ease of use like the c9000 :shrug: