I have a laptop from 2011 where the battery has now reached 90% Veschleiß by continuous network operation. Without power supply it switches off at load even at 100% charge and idle it consumes 2% per minute until it finally goes out at 70% residual charge and at 0% after it is taken with power supply back into operation.
Since I only operate the device on the net, I have now removed the battery, but gapes behind then a nice hole. So I decided to remove the cells, so opened the battery, severed cable, brought out cell by cell and the welded metal tracks removed… Now came back my interest why why why, meter brought and ran to the cells.
Datasheet of cells:
Rated voltage: 3.6V, end of charge 4.2V
Capacity 3100 mAh
Since the battery was previously "fully charged", my multimeter showed me at DC 4.02V in all cells. Now I wanted to measure the capacity and went to A (DC) 20A, since the other measuring fields max. 200mA tolerated.
As soon as the measuring tips were attached, the display showed 22.xx A and after 2 seconds the value began to drop rapidly, at 4A I removed the tips and noticed through my thick fabric sweatpants that the cell lying on my thigh became extremely hot, the green outside the film was getting brighter, have thrown the thing then panicking on the balcony…
WHAT HAPPENED?
You have shorted the battery.
https://de.wikipedia.org/...urzschluss
With a multimeter, A measures not the capacity but the flow rate. Normally one clamps cable 1 to the battery and cable 2 to the consumer. A third cable goes from the consumer back to the battery.
WHAT HAS HAPPENED THERE?
You fiddled with electrical parts of which you have no idea. You were lucky that nothing exploded there.
Closing batteries short is a very, very, very bad idea.
Congratulations.
You've built a short with your multimeter. If you're unlucky, you've also used it to shoot the meter in your multimeter.
You can't measure capacity. You can only measure the current. Capacity you can only calculate *. If a battery can supply 3A power for one hour before it is empty, it has a capacity of 3Ah (Amper hour…)
3Ah = 3000mAh.
The electricity coming out of the cell is regulated by the consumer. In operation, the laptop controls how much power it needs. In your case, figuratively speaking, you just put a wire from + to -. You were lucky that the cell was already quite at the end and could deliver only a short current peak (the 22.XXA will probably be the maximum value that your multimeter can map). A short-circuited 18650 cell can get over 100 ° C hot
* To completeness: There's the possibility to equalize the voltage of a cell with a capacity. But that's another topic that does not fit here
It turns out that I often used to sleep in physics. Ok… Again learned something…
Thanks for this enlightning answer… Now it shows again what I got in physics at the time and what did not. Well, the multimeter is still I think… Hopefully ^^
And yes, even right, it was a 18650A cell
By the way: The 18650ger cell has a lower discharge limit of mostly 2.5V (different depending on the type you have). Due to your short circuit here is the voltage safely (briefly) fell below this value. At least that leads to damage to the cell.
For further action:
Allow the cell to cool off on the balcony. And then please dispose in a battery box (should have Geschiebfft also sells batteries)
I had that anyway before when I go shopping tomorrow. Can I still dispose of the inflated battery pack from the iPhone 4 with that is already n year in a tin aufm balcony. But was a series defect and still has 0.0V
