is it suitable to charge 4V 750 V battery by 12V 30mA transformerless supply

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electrocraft

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is it suitable to charge 4V 750 V battery by 12V 30mA transformerless supply if howlong should i charge plz kelp
 

Re: is it suitable to charge 4V 750mah battery by 12V 30mA transformerless supply

plz ex cuse !!!!!!!!!!!!!!!!!!!!!!!!!!


battery to be charged 4V 750 mA And transformerless supply 12V 30 mA

- - - Updated - - -

:lol:
FvM said:
?? Please check the question.
Click to expand...

4v 750 mah battery and applying voltage 12v 30mA does battery explode in 12v 30 mA ???????????????!!!!!!!!!!!!!!!!!!!!!!!!!:shock:
 

if you use a current limiting resistor the over voltage will turn into heat but 12V @30mA = 360mW seems pretty safe. WHat should happen is the ESR of your voltage source would drop the voltage to match the battery without a resistor and if using a current limited supply. You can increase the current with OVP protection such as LED's of suitable power or voltage to clamp output to battery specs.

With 750 mA-Hr rating @ 30mA it will take 25~30hrs from 0% to 100%. which is safe but may increase unnecessary wear if it gets warm after fully charged.
 
if you want to design transformerless powersupply just look at this Application notes provided by MICROCHIP TECHNOLOGIES
 

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