Any practical guide to design li-ion battery charger?

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mohannadmaklad

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I want to design a circuit to make a power bank for a 5v 4A tablet.
it would be so great if someone guides me to a good tutorial about the theory and the practice.
also, as a citizen of third world country, i wish to find any circuit with popular ICs to make it.

thanks in advance...
 

Hi,

charging a LiIon battery is a problem of current and voltage.

There are several charging techniques described in the internet. They tell you how to set (change, regulate) current and voltage.

Knowing this you can use a
* microcontroller and
* a power supply (linear, switch mode...) with adjustable voltage and/or current. (acting as charging power source)
* voltage measurement
* current measurement.

Now your software/microcontroller measures voltage and current and adjusts the supply to get the desired charging characteristic.

****
But there are so many cheap ready to buy LiIon chargers around ... in my eyes it makes no sense to build your own.


Klaus
 
KlausST said:
But there are so many cheap ready to buy LiIon chargers around ... in my eyes it makes no sense to build your own.

Klaus
Click to expand...

could you recomment any of these cheap chargers?

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this also made me wonder, for the tablet or any battery powered device in general, is it the responsibility of the charger to measure both voltage and current or this function is implemented with internal circuitry in the device?
 

Hi,

for tablet: the external adapter is a "power supply", not a true "charger".
The charger circuitry is built inside the tablet.

Klaus
 
ok, one last thing, if i am designing a power bank using 3 cells of li-ion battery, do i connect them directly to the tablet using usb connection or do i need to add protection circuits (under voltage lock out , current limiting... etc) ?
 
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    rberek

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You will need protection circuits and use one voltage regulator circuit in your power bank. Your tablet cannot be receive voltage raring of 9 to 12.6 voltages.
 
u can buy with cheaper price , I think just check your output voltage matches with your tablet.. but higher current is no problem.. you device will draw the current as required.
 

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