Okay, i've scavenged up some 18650's, what do i do with them?

MacTech

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It was slow at work today, so i got bored and decided to tear apart a couple of my old PowerBook G4 Titanium battery packs, now i have 12 18650 cells, 4 Panasonics, 8 LG Electronics cells

the LG's seperate out into two groups, 4 test out at 2.98V, 4 at around 3.0 to 3.01V, the Panasonics appear to be dead, as they meter out at 1.2-1.4V, looks like that battery pack is overdischarged

now that i have these cells....

1; how do i recharge them?
2; what can i power with them?

I understand that a 18650 is roughly the same size as 2 CR123a's, so i'd imagine i could drive any 2 cell light with a barrel diameter wide enough to swallow the cells (sadly, they don't fit my A2, they're too wide)
 

mdocod

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first off... those are unprotected cells, so whatever you do with them, you need to be extra careful. the ones that are up around 3V should take a charge and be usable.

To see what you could do with them... there are a *few* options listed in the compatibility chart and plenty of information about li-ion setups in the guide... click on link in signature...

a DSD or ultrafire WF-139 will charge 18650s pretty well... just keep an eye on the voltage, make sure you don't over charge or over discharge. I would personally discard the panisonics, i don't think I would try to charge them up.


[edit in] come to think of it... if the cells are over 2 years old and used a lot, some would probably advise not using them at all.
 
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LuxLuthor

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Mac, please make sure you understand the dangers of Lithium Ion batteries. I worry about what can go wrong in a situation like you describe.
 

LEDcandle

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If the 2-cell light requires 2 x CR123a (6v), then a single 18650 (3.7v) is not going to power it properly. Some LED dropins and lights can take a very wide range, and those will work.
 

moon lander

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how many cells are in a powerbook battery? did any of the batteries contain more than 1 kind of cell? were all of the batteries dead according to the powerbook?

im no expert, but i wouldnt dare charge those panasonics, and with the rest, if you do charge them, make sure you have a fire extinguisher and dont leave. if they blow, dont breathe the fumes. how well they perform once they are charged might give you some idea of what shape they are in. im not an expert so you should probably ignore my advice.
 

mdocod

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I think I would advise that you charge the LGs under supervision to about 4.190V, measure voltage, and then see if they hold that voltage for more than a day or so... if it looses some voltage(like drops to 4.07), then they are hurting and will be dangerous to use. Maybe a resident battery expert like Silverfox could elaborate on this further and give specific advise about testing procedures.
 

Atomic_Chicken

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Greetings!

MacTech said:
Okay, so the general consensus is that they're unsafe?, i'll ditch 'em then, don't want to have to deal with HF acid poisoning.....

Not necessarily unsafe... just educate yourself before using them.

I'm pretty much in the same boat with LiIon batteries - I'm currently learning all I can about them, and from what I'm hearing so far, unprotected LiIons are just fine so long as you observe the proper precautions when using them.

Best wishes,
Bawko
 

LightBeing

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dealextreme.com has some very cool Cree lights that run on a single 18650. I charge my salvaged 18650's using a Nano-charger, spacer same size as a CR123 and a c-clamp setup with some pennies and wires all soldered to the pennies so it will charge any size Lithium Ion. A little slow but works fine and terminates at a good voltage.
 

leukos

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They are probably fine in single cell applications as others have already mentioned. New LG's can be had for $8-9 each, so you are probably only saving about $60-70 by not purchasing new ones.
 

SilverFox

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Hello MacTech,

Li-Ion cells are considered "dead" when they no longer can provide 80% of their initial capacity. Once you pass this point, strange things can happen and aging becomes non linear. This can be a problem in normal use and is a problem if you use more than one cell in an application.

The first step is to do a visual examination of each cell. If the cell is dented or damaged, recycle it.

Next you need to determine the initial capacity of the cell. The cells may be marked, or you may be able to get the information from the label on the battery pack.

The next step you have already done. Measure the voltage. Any cell below 3.0 volts is probably not worth the effort. 3.4 volts or higher is better.

Now it is time to charge each cell individually.

This is where things can get dicey, so take the normal safety precautions. Make sure you set aside a few hours to attend to the charge. Charge in an area that is free of combustible material. Finally, survey the area and ask yourself "If something goes wrong, what do I think will happen?" The picture I keep in mind is lighting a road safety flare. Sparks and smoke will be abundant and your charging area should be designed with that in mind. A fire extinguisher, or a bucket of sand, or a bucket of water handy is also a good suggestion.

On to the actual charging process. If you have access to a regulated power supply you can make up some leads and charge the cells. Using an accurate voltmeter, set the voltage on the power supply to 4.200 volts. The charging current is dependent on the cells capacity. The first charge should be done at around 0.5C or maybe a little lower. During the first charge, monitor the cell for heat. A damaged cell will heat up, a normal cell will not. If a cell heats up, immediately stop the charge, discharge the cell to 0 volts and recycle the cell. If the cell remains cool, you can increase the charging current up to a maximum of 1.0C. I find the shortest charging time for Li-Ion cells is at a rate around 0.7C. When the current drops to around 50 - 100 mA, the charge is complete. Remove the cell and check its voltage. A good cell will be very close to 4.200 volts. If a cell has aged and developed higher internal resistance, it will end up with a lower voltage. If it drops to 4.0 or lower, it is generally considered "dead."

Note that this voltage measurement is a resting, open circuit measurement with a rest period of around 15 minutes.

Now you have some cells that are charged up and ready to go. I do a capacity check on the cells at this time. I discharge the cells and compare their capacity now with their initial capacity. I have the equipment to do this, and log the data for future reference. If you don't have discharge test equipment, you can do a runtime test with a light that the cell works with, and test that way.

Once you have confirmed that the cells are "good" and have gone through a couple of charge/discharge cycles without problems, you then can consider trying to match the cells for multi cell applications.

As others have mentioned, Li-Ion cells have a very slow self discharge rate. Any cell that you notice a voltage drop over a few days of storage probably is developing internal shorts, and should be recycled.

Good luck, and remember to charge safely. Li-Ion chemistry is very nice in that there is no problem shutting the charger off and interrupting the charge. If you have to run an errand or leave the area, shut the charger off. When you get back, turn it back on and continue the charge. The cells will charge normally in spite of the interruption.

Tom
 

Eggpar

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Hello MacTech,

Li-Ion cells are considered "dead" when they no longer can provide 80% of their initial capacity. Once you pass this point, strange things can happen and aging becomes non linear. This can be a problem in normal use and is a problem if you use more than one cell in an application.

The first step is to do a visual examination of each cell. If the cell is dented or damaged, recycle it.

Next you need to determine the initial capacity of the cell. The cells may be marked, or you may be able to get the information from the label on the battery pack.

The next step you have already done. Measure the voltage. Any cell below 3.0 volts is probably not worth the effort. 3.4 volts or higher is better.

Now it is time to charge each cell individually.

This is where things can get dicey, so take the normal safety precautions. Make sure you set aside a few hours to attend to the charge. Charge in an area that is free of combustible material. Finally, survey the area and ask yourself "If something goes wrong, what do I think will happen?" The picture I keep in mind is lighting a road safety flare. Sparks and smoke will be abundant and your charging area should be designed with that in mind. A fire extinguisher, or a bucket of sand, or a bucket of water handy is also a good suggestion.

On to the actual charging process. If you have access to a regulated power supply you can make up some leads and charge the cells. Using an accurate voltmeter, set the voltage on the power supply to 4.200 volts. The charging current is dependent on the cells capacity. The first charge should be done at around 0.5C or maybe a little lower. During the first charge, monitor the cell for heat. A damaged cell will heat up, a normal cell will not. If a cell heats up, immediately stop the charge, discharge the cell to 0 volts and recycle the cell. If the cell remains cool, you can increase the charging current up to a maximum of 1.0C. I find the shortest charging time for Li-Ion cells is at a rate around 0.7C. When the current drops to around 50 - 100 mA, the charge is complete. Remove the cell and check its voltage. A good cell will be very close to 4.200 volts. If a cell has aged and developed higher internal resistance, it will end up with a lower voltage. If it drops to 4.0 or lower, it is generally considered "dead."

Note that this voltage measurement is a resting, open circuit measurement with a rest period of around 15 minutes.

Now you have some cells that are charged up and ready to go. I do a capacity check on the cells at this time. I discharge the cells and compare their capacity now with their initial capacity. I have the equipment to do this, and log the data for future reference. If you don't have discharge test equipment, you can do a runtime test with a light that the cell works with, and test that way.

Once you have confirmed that the cells are "good" and have gone through a couple of charge/discharge cycles without problems, you then can consider trying to match the cells for multi cell applications.

As others have mentioned, Li-Ion cells have a very slow self discharge rate. Any cell that you notice a voltage drop over a few days of storage probably is developing internal shorts, and should be recycled.

Good luck, and remember to charge safely. Li-Ion chemistry is very nice in that there is no problem shutting the charger off and interrupting the charge. If you have to run an errand or leave the area, shut the charger off. When you get back, turn it back on and continue the charge. The cells will charge normally in spite of the interruption.

Tom
HI Tom,

Could you talk about your testing equipment? I would like to set myself up with good yet affordable testing and charging capabilities preferably for a flexible system for multiple sizes and chemistries of lithium cells. Any help appreciated.
 

Dave_H

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Ottawa Ont. Canada
"

what do i do with them?​

Buy them all flashlights, of course!

Of course!

There are lots of small cheap 3xAAA LED flashlights using round cell holder, some of which can take an 18650; others are too short and cannot, but should take an 18500.

You can usually spot these by looking inside the battery tube. If there is a spring at the head end (down the tube) and on the tailcap, it should take an 18650. Also, if the cell holder has a spring-loaded pin at one end, good chance of fit. This is how I figure out in-store if the light will take 18650, unless it's sealed in its package.

The 18650 is smaller diameter than the tube but may be held tight by the springs. I cut a short length of thin-walled PVC tube as spacer to take up the difference. Regular PVC water pipe wall is too thick.

The lower voltage may have a minor effect on brightness, depending on the driver. I find mine acceptable.

Keep in mind that a lot of these cheaper lights do not have low-voltage cutoff for Li-ion, so to avoid damage by over-discharge, one should cut off operation before it happens. You will usually note some drop in brightness at some point.

There are a few 3xAAA lights out there which will take an 18650, but rely on internal cell resistance of alkalines for current limiting; cheap deficient design in my view. These will light brightly but have limited lifetime using 18650 which has low internal resistance...just a warning.

Lastly, as others are saying, treat these with great care, they are most likely unprotected cells. Using two in series has risks. If you do this, I would use two from a pair which were originally paired in parallel in the pack, and are proven good.

Dave
 
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