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Battery charging indicator circuit design

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Pavi98

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Hello all ,
I have made a rechargeble battery pack using two 18650 batteries in series with a 2S BMS circuit. I need to make a battery charging indicating circuit with the functionality of blinking LED while the battery pack is being charged and keep the LED on after the battery is fully charged. I searched for a circuit diagram but couldn't find for this functionality. How can I design an indicating circuit for this application?

Thank you
 
A gas gauge circuit excellent way of doing it. Controls charging and
battery state.


Or Arduino based, just google "arduino 18650 charging project"


Regards, Dana.
 
Its complicated, depends on type of battery. Here is LiOn

LiOn Charging :




So this process normally handled by a low end micro to control the CC and CV.

NiCads and lead-acid different, battery handbook :




Regards, Dana.
 
Note that the EVreporter article Dana linked gives you the threshold for detecting end of charge from current. 0.05C. So, with a typical 18650, this would be in the 100mA ballpark. Which surprises me. I would have thought 10mA OOM.
 
Note that the EVreporter article Dana linked gives you the threshold for detecting end of charge from current. 0.05C. So, with a typical 18650, this would be in the 100mA ballpark. Which surprises me. I would have thought 10mA OOM.
No, you would have thought dangerously wrong - 0.05C is the fully charged point, assuming you're slow charging, in order to get maximum capacity. If you're fast charging you stop charging far earlier, sacrificing capacity for speed of charge.

With my Samsung 2600mAH 18650's my cut-off point is 130mA.
 
So you can see Pavi98 there is no one simple solution, so you have to plant your
flag in design goals and choose what you feel is practical usable end of charge
current. And of course make sure your charger can accommodate the variants
to insure public safety.

Other considerations :





Regards, Dana.
 
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