are computer 18650 protected

[riasa]

I broke open a computer battery pack to use the 18650s. How can I tell If they are protected or not?
.

 

[DM51]

They will not be protected once you have removed them from the pack. The protection circuit is in the pack, but the bare cells do not have individual protection.

I'm going to move this to 'Batteries Included'.

 

[chee]

Just out of curiosity - are these batteries still good to use for flashlights? Presumably you broke open a 'used' battery pack. I have a lot of used (1-2 years) laptop battery packs at work and I've often wanted to break open one just to see what is inside. However, I don't know if there is actually a safe way of doing that.

 

[DM51]

Obviously you need to be careful breaking open the battery pack. If a cell is damaged in the process, don't try to use it. Quite a few other people here have done it OK.

If the cells can take a charge, you can use them. You need a safe charger that will terminate properly at 4.20V, as the cells are unprotected.

If after resting for an hour the voltage has dropped from 4.2V to 4.0V, they have had it and should be thrown out.

 

[Illum]

most electronics that uses 17670 or 18650s have protection on a seperate PCB. Its more of a "batch protection" that prevents blowouts caused by overcharge or overdischarge.the PCB, however, does not balance the cells during charge...hence theres reports of disassembled battery packs with good cells [1.5-3.5V, recoverable but tricky] and the bad cells [<1.5V and sometimes reverse charged cells]

I think only recently someone came up with the idea of installing built-in protection to cells. such as AW, Ultrafire, Trustfire, etc. Lithium ions are still considered industrial grade lithium cells...I doubt this technology would become widespread in consumer products soon...as anywhere outside the forum no one I can find will understand its characteristics:candle:, except the flashaholics I manage to convert :nana:

 

[DM51]

Good point there from Illum - you need to check the voltage of each cell before trying to charge them, as well as after.

If any cell reads below 3.0V, it has been over-discharged, and care needs to be taken with it. If below 2.5V, best leave it alone. Certainly do not touch anything below 2.0V.

 

[Illum]

Good point there from Illum - you need to check the voltage of each cell before trying to charge them, as well as after.

If any cell reads below 3.0V, it has been over-discharged, and care needs to be taken with it. If below 2.5V, best leave it alone. Certainly do not touch anything below 2.0V.

a few intelligent chargers [Pila for one ] have been reported for refusing to charge cells under a minimum threshold presumably for protection..while other chargers [heard from a ultrafire user:ironic:] will charge any cell given the impedance or resistance is sufficient to override the charge sensor...if you shoved in a 0V unprotected battery into your charger...and it starts charging, your looking at a incendiary grenade with an long and unpredictable delay, AKA when you least expect it

also, the rate of temperature will increase rapidly when the cell is also charged to full capacity. if the cells on the charger and feels warm, might be a good idea to remove it, test it, then go from there.

ALWAYS REMEMBER TO MARK YOUR unprotected BATTERIES POLARITY CLEARLY
I've had the privilege of reverse biasing AW protected 14500s...as far as the reaction goes its just sat there heating up. now an unprotected 14500 might take out my DSD charger faster than I can with a hammer:candle:

heres a reasonably accurate capacity to voltage converter
OCV with no load

100%----4.20V
90%-----4.06V
80%-----3.98V
70%-----3.92V
60%-----3.87V
50%-----3.82V
40%-----3.79V
30%-----3.77V
20%-----3.74V
10%-----3.68V
5%------3.45V
0%------3.00V
​

below 3V is recoverable....but generally not recommended

 

[chee]

Thanks for all these very helpful information. I'm fairly new to Li-Ion cells and still learning so this is good.

 

[Logrus9]

I have a few questions but I didn't wat to start another thread.

Is the outer colored wrapper insulation? If it's nicked can the battery be used safely?

If two cells are soldered in parallel can they be charged by putting one in the charger and having one sticking up in the air? I'm using the Ultrafire W139.

 

[lctorana]

...when testing OCV...heres a reasonably accurate capacity to voltage converter [voltage under 550ma load]...

Great post. Really useful. (I have some unprotected 18650s myself, includiing 2 from my mobile phone before last.)

One question - are the above voltages under no load or 550mA load conditions? Your sentence is a little ambiguous.

 

[SilverFox]

Hello Logrus,

Welcome to CPF.

Yes, the outer wrapper insulates the can of the cell from your flashlight. If nicked, it should still be OK, but if you can see where it would short out, you can put some nail polish in the nick to insulate it.

If your cells are connected in parallel you should have no problems, but keep in mind that it will take longer to charge.

Tom

 

[Illum]

Great post. Really useful. (I have some unprotected 18650s myself, includiing 2 from my mobile phone before last.)

One question - are the above voltages under no load or 550mA load conditions? Your sentence is a little ambiguous.

I edited it, the measurements represent the voltage when under 550ma load, but thats rather confusing. after relocating my sources I found they had provided a chart for purely OCV with no load.

so, edited.

source: [Chinese] 鋰離子電池容量計算之電壓法 [Lithium-ion battery capacity calculation: voltage method]