Li-Ion battery pack "alien autopsy"

I was recently given a supposedly dead laptop battery pack, I disembowelled it, and found 15
Panasonic CGR18650 cells in it, wired in a series-parallel arrangement of 3 series groups of 5 cells wired directly in parallel. These are (I think) 1800 mA/H cells, at 3.6 volts. It also has a small charge controller board, which may be what was bad with it. Even if only a few cells are weak or bad, the price was right...

Lot's of LED power coming up....

/ed brown in NH

Originally posted by Hemingray:
I was recently given a supposedly dead laptop battery pack, I disembowelled it, and found 15
Panasonic CGR18650 cells in it, wired in a series-parallel arrangement of 3 series groups of 5 cells wired directly in parallel. These are (I think) 1800 mA/H cells, at 3.6 volts. It also has a small charge controller board, which may be what was bad with it. Even if only a few cells are weak or bad, the price was right...

Lot's of LED power coming up....

/ed brown in NH

Click to expand...

<font size="2" face="Verdana, Arial">Ed, I have a lot of experience working with Li-ion cells. For your scenario, any cells that "as found" were reading over 2.5V are very likely good though if it was a well used battery pack may not meet the original capacity specs. Any cells reading under 2.0V "as found" send these straight to the waste can.

And don't you also have to keep some kind of charge controller in there? Something HAS to disconnect the cells before they fall below a certain voltage or they will just die the first time you drain them.

Not to mention that it has to protect them from shorts or they will catch fire and protect them from charging at too high or too low a temperature or they will die, and disconnect them permanently if the temp of the cell ever gets beyond a certain point because they have already died. (Perhaps thats what happened with this pack, it got left in the glove compartment and it cooked the cells.)

LiIon cells need a lot of coddling!

-James

This has a small controller board, with three outputs, looks like it is set up for 3.6, 7.2 and
10.8V (plus 0V "ground") and has heavier leads
for the battery output.
I'll check the voltages, to see if they are over 2.5 Volts. BTW the date code is 1999, FWIW.

Thanks

/ed brown in NH

Just did a quick check - two groups (of 5 cells
in parallel) show 3.6 Volts, the middle group is
about 0.6V, so that one has at least one bad cell.
I'll separate them and see if it is one, or all.

I haven't seen this method of paralelling cells
directly before, but it seems to work for this
application.

The remaining 7.2V should be just about right for
feeding a 5 watt Luxeon (with an appropriately
sized resistor, about 2 Ohms). If they are good,
that's about a 10 hour runtime. 8=)

/ed brown in NH

Originally posted by Hemingray:
Just did a quick check - two groups (of 5 cells
in parallel) show 3.6 Volts, the middle group is
about 0.6V, so that one has at least one bad cell.
I'll separate them and see if it is one, or all.

Click to expand...

<font size="2" face="Verdana, Arial">Ed, don't bother to separate the cells in that one group, they are all bad now.

I separated the three 5-cell parallel groups,
two are good, the center one was flat as 3 day old warm beer

I hopefully have some more packs coming my way, so I can make a good one, or at least more 7.2V packs for the 5 watt Luxeons.

Thanks for the help.

/ed brown in NH

This Panasonic website has it all...

http://www.panasonic.com/industrial/battery/oem/chem/lithion/index.html

/ed brown in NH

Diameter Inch (mm)
Height Inch (mm)
ThicknessInch (mm)
CGR17500 3.6 830
0.67 + 0/-0.03(16.9 + 0/-0.7)
1.95 + 0/-0.04(49.6 + 0/-1.0)
--- 0.88(25)
CGR18650HG 3.6 1800
0.73 + 0/-0.03(18.5 + 0/-0.7)
2.56 + 0/-0.02(65.0 + 0/-0.6)
--- 1.48(42)
CGR18650A 3.6 2000
0.73 + 0/-0.03(18.5 + 0/-0.7)
2.56 + 0/-0.02(65.0 + 0/-0.6)
--- 1.52(43)

(Size "AA") .571 (14.50)1.988 (50.50)
(Size "AAA").413 (10.49)1.752 (44.50)

I guick ref the size compare with AA&AAA.
You can't just direct put the Li-Ion into your AA or AAA size flashlight. Why not? Or is there AA or AAA size Li-Ion?

Thanks

You can't just pop a naked LiIon cell into a flashlight, or anything else for that matter for the same reasons I mentioned above.

If you run them below about 2.2 volts (can't remember exactly) they are toast. After that they will not charge. The charge controller circuitry cuts them off at this point. If you just put them into a flashlight, the first time you run them down thats it, no more.

If you short them they catch fire. The charge controller protects them from shorting by cutting them off at higher than rater current.

If you charge them at too high a current they overheat and are toast. The charge controller protects them from that.

If you charge them at too high or too low a temperature they are toast. The charge controller has to handle that too.

And finally if the temperature of the pack ever goes over a certain point, be it while charging or draining or just because you left them in the car, then the charge controller has to cut them off permanently as they are toast.

It's certainly possible to build the charge controller into an individual cell, or a couple of cell pack. But a raw LiIon battery in the shape of a C or AA is just not going to happen until someone can embed the charge controller into the nib on the top or something.

There are LiIon packs in the shape of 2 D cells that have all the circuitry inside it. Someone around here recently linked to it as part of a rechargeable flashlight. I expect we'll see more of these things as time goes on, we're just a bit ahead of the curve around here

Originally posted by James S:
You can't just pop a naked LiIon cell into a flashlight, or anything else for that matter for the same reasons I mentioned above.

Click to expand...

<font size="2" face="Verdana, Arial">While I wouldn't design a commercial mass market product this way, a modder can get away with no overdischarge protection if using a single cell to run a InGaN Luxeon since the LED will quit drawing current at around the minimum allowable cell voltage. Similarly, a modder with a variable power supply and a reasonably accurate DMM, can charge them with no special provision. I would suggest setting the PS Voc no higher than 4.15V to allow for power supply drift and meter inaccuracy.

These particular cells are longer and fatter than AA (or AAA) cells, so they would not fit into a
normal penlight-sized device. Maybe they could be
worked into a C or D cell flashlight, with an adapter to hold them centered. Howeve (there's that word again) Lithiums should not be put into a hermetically sealed (read that waterproof) container, they can and do outgas, and that could cause problems.

These cells in the pack do not look like the ones
in teh web page, these have a hot pink insulator shrunk on them, and the printing (in many languages) is black text. When I first saw this naked pack sitting on my office chair, I first thought that Al Quidah had left me a "present" as it did look like the guts for a bomb... All those pink cylinders and wires sticking out all over 8-0

/ed brown in NH

The 2 A Lithium Ion packs from Balsa Products are this same size, there are two cells in series and a small control/protection board inside the generic looking white (or light gray) shrink tubing, about 5 1/4 inches long x 3/4 inch diameter, and there are soft foam rings around this (which can be peeled off) , with a pair of leads terminated in a small molex type female connector. This can be charged with a 8.2 to 8.4 VDC source, I use a home made supply and LM 317 adjustable regulator.

Li-Ions are not for the casual uninformed consumer, they need lots of attention to details,
in order to be safely used.

/ed brown in NH

Originally posted by Tsao:

(Size "AA") .571 (14.50)1.988 (50.50)
(Size "AAA").413 (10.49)1.752 (44.50)

I guick ref the size compare with AA&AAA.
You can't just direct put the Li-Ion into your AA or AAA size flashlight. Why not? Or is there AA or AAA size Li-Ion?

Thanks

Click to expand...

<font size="2" face="Verdana, Arial">Alan, see this thread: http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=000767

Since you're in Taiwan you may have an easier time contacting these companies.

Just for the halibut, I decided to try to rescuscitate (sp?) the LI-Ions that read .6V, hooked them up to my trusty little home made adjustable power supply, ramped it up to 4.2V,
and after about 24 hours, they charged up, and so far, they seem to be holding the charge. I kept the current at 1/2amp or less during the charge, and no fire, smoke or noxious gasses resulted...

So, perhaps there is an after-life for those allegedly dead cells.

/ed brown in NH

There must be AA size Li-Ion rechargeables, the pack for my older Sony Mavica digital camera has two approximately AA-sized cells and the charge controller board within. I haven't yet performed an "alien (as in outer space) autopsy" on it yet. AAA size may be pushing the envelope, AA size seems reasonable, the Panasonics in my earlier post are A sized. Too long/fat to fit in
an AA space.

/ed brown inNH

Originally posted by Hemingray:
Just for the halibut, I decided to try to rescuscitate (sp?) the LI-Ions that read .6V, hooked them up to my trusty little home made adjustable power supply, ramped it up to 4.2V,
and after about 24 hours, they charged up, and so far, they seem to be holding the charge. I kept the current at 1/2amp or less during the charge, and no fire, smoke or noxious gasses resulted...

So, perhaps there is an after-life for those allegedly dead cells.

/ed brown in NH

Click to expand...

<font size="2" face="Verdana, Arial">My experience with cells discharged to that level is that they will take one or two charges and then the capacity declines rapidly with subsequent charges. I would be interested in what you find.

I'lltry them out in a white LED / resistor load,
so as to not drain them too far down. Will be an interesting experiment. If they are weak, then they will end up in my almost overflowing dead battery box, that I take to the local recycling center when it fills up. They will take just about anything, but they were a tad nervous when I brought in a "stick" of 6 solder tabbed C size nicads that was all wrapped up in black electrical tape. They hadn't seen anything like that before.

/ed brown in frozen wastelands of NH