Havesting lithium ion cells out of laptop batteries

[amateur_24]

Hi I have two dead laptops in my room. One doesn't boot at all and the other has a dead screen. I opened up the dell battery and found 6 lithium cells.
According to the rating on the pack, it's 11.1v @ 4.8Amps. I want to reuse the cells for a spare led torch if I can.

here's the questions
1)Are I correct in saying each cell should be 3.7v
3x 2.4 -2.6v
3x 2.2v
So am assuming the 2.4 ones are good and the 2.2v ones are bad?

2) what size are these batteries ?

 

[alec_t]

Do the cells have individual protection circuits attached?
Are you aware of the hazards lithium batteries can pose if not charged/discharged correctly? (If not, check out BatteryUniversity)

 

[amateur_24]

Yes of course. The hazard is plastered all over youtube. My favorite is this video

.
I plan to use one of sparkfun's charger instead of building my own. Am I correct in saying the batteries are 18650 cells. I'm unsure they do have protection. HOwever I can add a protection ic can't I? AFAIK it's an original battery since the laptop was from work. They were giving them away.

 

[throbscottle]

Cells out of a Dell laptop battery will not have internal protection (I know because I was going to re-cell mine) they are plain cells. All the magic is done in the battery's internal circuit.

 

[amateur_24]

Ah OK. I was going to use a comparator to detect when an invididual cell voltage was 3v or below. Then shut off the entire pack. So I could use a MOSFET on the output of the pack. Also temperature monitored. What sort of temperature should be the cut off