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

[electrocraft]

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

 

[Magvitron]

4v 750 v??

 

[FvM]

4V 750 V battery

?? Please check the question.

 

[D.A.(Tony)Stewart]

It is possible if you do not mind waiting days with a switched inductor to boost the voltage. Why would choose that? 4A battery? 30mA source?

 

[electrocraft]

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

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:lol:

?? Please check the question.

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

 

[D.A.(Tony)Stewart]

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.

 

[yogece]

if you want to design transformerless powersupply just look at this Application notes provided by MICROCHIP TECHNOLOGIES