What to do with the 8 18650's out of my Laptop Battery?

[cam94z28]

I bought an off lease Dell C610 with a battery that was DOA. It is a 14.8 volt 3600mAh Li-Ion. A few days ago I was bored and tore it open. I was surprised to find 8 Sony 18650's contained inside, part number US18650GR.
How could it have 8 18650's if it's only rated at 14.8 volts? There is a sony circuit board in the housing, for pushbutton testing of charge level. Maybe part of this also limits the voltage.

I tested the cells individually after ripping the pack apart. 3 of them tested around 0.15 volts, two tested, 0.00 and 3 tested 1.90 volts. I put each one on the DSD charger for about 5 minutes, and all were holding around 3 volts. I left one in the charger, and it is still charging at 4.1 volts, and is cool to the touch. I wonder if something in the wiring is what killed them. Considering they will all hold a charge separately, I'm surprised they wouldn't charge in the laptop. Maybe they were over-discharged below some kind of threshold voltage.

I can use 1 or 2 of them in my 2xRCR123A lights, but I don't know if I can use all 8. I do know one thing, the pack is not going back together. I had to break off all of the aluminum foil thickness bars that were holding the pack together, and the way it was wired was very funky.

 

[DUQ]

Those packs are spot welded together. You can use a file to smooth the little spikey tabs down. Most of my cells come from laptop power packs. I have had no problems with them. I recycle the ones that read 0v.

 

[cam94z28]

Do you think I should toss the ones that read 0.00? After sitting for an hour they're still showing 2.8v. I only charged them for about 5 minutes.

I used fine tip wire cutters on the nubs, but there are still small bumps left. I guess a file is the way to go.

 

[havand]

If you have one of those advanced chargers ( like i just ordered ), you could try cycling them a few times to see if they come back to life...

 

[cam94z28]

I have a C-9000 for NiMH, but all I have is a DSD charger from DealExtreme for Li-Ion. I have a CBA II for discharging, so I guess I could run them through that a few times and see if theres an improvement.

I don't know what to expect though, the whole pack was rated at 14.8 Volts, and 3600mAH.

3.7 volts (I'm assuming) * 8 = 29.6 Volts.
3600mAh / 8 = 450 mAh.
If they are really that low in mAh, maybe thats why they need 8 :thinking:

 

[havand]

No no. The pack was 4 sets in series of 2 batteries in parallel. They weren't all in series.

Voltage:
3.7*4=14.8 V

Capacity:
1800mAh/cell 1800*2=3600mAh.

So there you go. 14.8V @ 3600mAh.

 

[DUQ]

I cycle all of mine in my RoP. You may also notice that some of the cells top off at ~4.1v and some at ~3.8v Dont forget to label and match them for use in multi cell lights. We dont want a to happen.

 

[cam94z28]

No no. The pack was 4 sets in series of 2 batteries in parallel. They weren't all in series.

Voltage:
3.7*4=14.8 V

Capacity:
1800mAh/cell 1800*2=3600mAh.

So there you go. 14.8V @ 3600mAh.

I was oversimplifying things, as usual. Yet another reason I'm not even going to attempt to put the pack back together.


If they're really 1800mAh each, I guess they could be useful in lights.

I cycle all of mine in my RoP. You may also notice that some of the cells top off at ~4.1v and some at ~3.8v Dont forget to label and match them for use in multi cell lights. We dont want a to happen.

Actually the first one I charged went to about 4.3 volts, which is what my RCR123A's do.

 

[barkingmad]

Personally I would probably bin the lot - these sound like possibly old / damaged cells that have already done their service. They are also probably unprotected cells and lithium cells can be dangerous!

At least if while you are testing them - do it outside if possible!

 

[DM51]

You are heading for trouble here, especially if you are using a charger that takes cells to 4.3v.

 

[WildChild]

Usually, Li-Ion cells should not be discharged under 3V without great capacity loss... Under 2.5V, you risk explosion when you will charge them... They are all dead! Throw them away to be safe.

 

[Fallingwater]

Do you think I should toss the ones that read 0.00? After sitting for an hour they're still showing 2.8v. I only charged them for about 5 minutes.

I used fine tip wire cutters on the nubs, but there are still small bumps left. I guess a file is the way to go.

I say toss them.
I had a similar experience with an Acer pack.
Four of the eight 18650s were at about 3.5v, two were at zero or close to zero and two were reversed.

The reversed cells were beyond hope. I now use them to roll solder wire on.

The zeroed ones did accept a charge, and even managed to light up my flashlight, but had ridiculously quick self discharge and were back to zero in a few days.

The other four are still good, and I regularly use them on my modified mp3 player and U2-style DX flashlight. They hold about 1300mah of the original 1800... which is quite surprising, considering they are at least six years old, used, and left for dead in that pack for at least two years.

 

[havand]

I have a C-9000 for NiMH, but all I have is a DSD charger from DealExtreme for Li-Ion. I have a CBA II for discharging, so I guess I could run them through that a few times and see if theres an improvement.

Sorry if this is a stupid comment as i'm not familiar with the CBA II, but does that have a discharge set limit? It isn't going to discharge the cells until they're dead, right? That could be dangerous. 2.5V is hurting the cell. There reallyisn't any benefit to discharging them past, say, 3V. Just a thought.

 

[DUQ]

I place a meter on mine while they are charging. I pull them when the voltage hits 4.1v I'm planning on switching over to AW cells...someday

 

[LEDite]

cam94z28;

Only the 1.9 VDC cells may be reusable.

Second, the 1800 mah cells are 3 or morel years old and have lost ~30% capacity.

#18650 cells went to 2000mah, 2100mah, 2300 and 2400mah capacity after the 1800mah series.

If these limitations don't bother you, then go ahead and use them.

I would look for newer #18650 cells.

Larry Cobb

 

[JamesWong]

All these 18650 are unprotected cell. Because the protection circuit is inside the bettery pack, not individual cell.

To use this cell safely, I would recommend :

1. Use a charger which end the charging at 4.1-4.2V, absolutely not >4.2V.

2. For cell voltage <2.5, it is dead. Throw it away.

3. Use it at LED flashlight with direct drive (just resistor). It is a good match, white LED will draw almost 0 current when voltage is below 3.0V. So it will not overdischarge the cell. Also you will aware the cell voltage is getting low by dimmed output.

4. Don't use on LED flashlight with regulator circuit, it will suck the power from the battery even at <3.0. The battery will then be dead. And it may not be noticed from the level of light output until it is too late.

5. When you turn on the flashlight with this unprotected cell. If you don't see it light up, turn off immediately and check the battery.
I has an experience of short circuit at the lamp assembly. Because there is no current limit protection, the short circuit current produced heat which melt the plastic part of my flashlight. If I would have turned off the flashlight too late, it may even exploded.


Just some advices.

 

[barkingmad]

Sorry if this is a stupid comment as i'm not familiar with the CBA II, but does that have a discharge set limit? It isn't going to discharge the cells until they're dead, right? That could be dangerous. 2.5V is hurting the cell. There reallyisn't any benefit to discharging them past, say, 3V. Just a thought.

The CBA-II has preset discharge to voltages for various cell types (although you can override it)...

 

[VidPro]

I tested the cells individually after ripping the pack apart. 3 of them tested around 0.15 volts, two tested, 0.00 and 3 tested 1.90 volts. I put each one on the DSD charger for about 5 minutes, and all were holding around 3 volts. .

i wouldnt want to use any of them.
chances are the pack fried because of an inbalance , and age and the low discharge makes them a libility, and of low capacity. for some 5-7$ you could get some good new ones, with more capacity, for 7-9$ you could get something in protected besides.
nothing good can come of it, even though it may look that way at first.
there are packs that have many good cells in them after a few failed, but that dont sound like one of them.