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My charger charges 18650 cells to 4.3+V. How safe is it?
#1
Hello everyone,

I have just started harvesting 18650 cells from deal laptop batteries and using a charger i bought from China.

My issue is that it overcharges the cells. Highest value I've come across so far is 4.37v.

Now I know that li-ion cells are very stable, but still, are there any risks that I should be aware of?

Also, I read from a post in batteryuniversity that storing the cells when full or overcharged could reduce their usable capacity. How long would they need to be in this overcharged state to damage them? I'm only charging them to do a self-discharge test, and don't intend to keep them in that state for more than a month at a time.

TIA for all your help  Smile
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#2
Your information about harm to the cell's life and that there is danger under sustained overcharge of fire is correct. I suppose the voltage readings could be off - buy unless you can independently verity I would recommend you use a different charger.
Korishan likes this post
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#3
Its not Safe and liion Arent that Stable i would say.

Scrap that Charger but before you do that crosscheck your multimeter so that One isnt lying Smile
Crimp Daddy, Korishan, 100kwh-hunter like this post
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#4
I agree with both OffGridInTheCity and Daromer. Verify using a reliable voltmeter (a cheap one is fine as long as it's been calibrated [the 4 I got from Harbor Freight were all off by about +/-0.3V]). Then you can either choose to keep using that charger knowing what it's off by, check to see if it's possible to calibrate it (some of these devices have a trimpot inside, or SPI connectors to be used with something like an arduino or such; this is much more complicated tho), or get a new unit.


What charger do you have, anyways?
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#5
I agree with the above.  Not safe, not stable... any overcharge can create damage or potentially dangerous situation.  

I would validate / check all your equipment to make sure nothing is lying to you. 

Most all my test equipment goes though an occasional accuracy check as well.

Geek likes this post
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