Hi Arsenijs,

> Am 14.11.2017 um 19:10 schrieb Pičugins Arsenijs <[email protected]>:
> 
>> But are they safe for those batteries ? Did you try them?
> 
> I have disassembled some of the "universal springy pins" chargers and they do 
> not seem safe, they don't seem to use specialised charging ICs and usually 
> use some kind of half-assed passives-based solution that ignores the CC/CV 
> cycle requirements for LiIon charging. They could be safe to use if you were 
> to throw out all the electronics and replace them with your own.
> 
>> I half remember most smartphone batteries include a charger chip
>> and GTA04 batteries do not (the chip is in the phone and should be
>> in the charger).
> 
> That is definitely not the case. 99.999% is that the "charger", that is, the 
> thing with a MicroUSB cable you plug into the wall socket, only provides 
> constant voltage and some guarantee about max current available (say, 5V/2A). 
> The phone has a charging chip inside, which takes 5V and uses it to charge 
> the battery, controlling the charging rate and stopping the charging process 
> when the battery is full. The battery itself doesn't have any provisions for 
> charging inside, aside from a protection circuit that prevents it from 
> overcharging (doesn't have to be there, but is included in 99.999999% phones 
> with LiIon batteries),

The GTA0x batteries we are considering here have such a protection inside.

> and a thermistor so that the charger can measure temperature of the battery 
> and stop charging when the battery is too hot. Talking about protection 
> circuit, it protects from 1) discharging the battery too deep (because it 
> will get damaged, and in certain circumstances might burst into flames when 
> charged the next time), 2) overcharging the battery (even though the cha
> rger is not supposed to do that, there's still a small chance, like charger 
> short-circuiting 5V onto its output because of a power surge) and 3) 
> short-circuiting the battery. Again, that is just how phones are built, at 
> least for a decade now.

You were faster and more elaborate than I was :)

BR,
Nikolaus

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