hi.
i own little IT service.
i have not little mobile phone batteries.
Want to discharge them first (maybe with Resistance ? ) and then put it on my universal mobile phone batteries charger to make them full.

Is this with Resistance right and what to be the value and maximum heat over it in watts?

 

Ideally you would be better using a Constant Current discharge, this will discharge it linearly until it is flat.

With a resistor the current will decrease as it gets lower in voltage, and will take longer, if you want to use a resistor try a 16 ohms 5W.

Discharge the cells at 10% of their capacity, so if the battery is 3600mA, use 330-360mA.

 

Why do you think you need to discharge them first?

 

Why do you think you need to discharge them first?

And what chemestry are they (NiCd, Lipo, etc..)? Some chemistries should be occasionally discharged, most modern chemestries do not like being fully discharged.

 

the idea is selling maybe...this way they only collect dust

want to discharge them like the battery is pluged in phone and on screen there was a message "low battery"

then put it on the charger and see the battery is charging 2-3 hours for example so i am making the conclusion "the battery is relative good"

 

Ahh a battery tester! That makes sense. Do you want to track how much energy comes out of the battery as it discharges?

 

And what chemestry are they (NiCd, Lipo, etc..)? Some chemistries should be occasionally discharged, most modern chemestries do not like being fully discharged.

That's what I was wondering - nickel chemistry likes the occasional complete discharge, but there's a risk that one cell gives up first and the others push reverse charge through it. that turns a weak cell into a shorted one. Particularly on cordless tools - they're not a good approximation to constant current charger. The lower terminal voltage causes an increase in charge current and more shorted cells - this usually kills the charger.

Lithium has a minimum allowable terminal voltage. My e-cig gets over discharged occasionally - the consequences don't seem to be all that devastating.