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Reducing Li-Ion battery voltage

jzeds1491

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Hi i need to reduce voltage of a 4.2v protected battery which is in a circuit. I need the output to be 4.1 or below it .. Also it's not important to do it by not fully charging battery. Any simple solution?
 

RCinFLA

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4.2v is maximum charging voltage for LiPo battery and should not be held at that voltage.

Normal battery range is 3.7v to 3.9v so if you truely need 4.1v you will require a buck-boost DC-DC converter.
 

jzeds1491

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4.2v is maximum charging voltage for LiPo battery and should not be held at that voltage.

Normal battery range is 3.7v to 3.9v so if you truely need 4.1v you will require a buck-boost DC-DC converter.
Yes exactly, idk why , maybe protection circuit is broken but that battery exxceds 4.2 easily . I need a solution to prevent that from happening.(by not letting it to charge to 4.2 for example )
 

d123

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Hi,

Old-fashioned and simple way could be LM3914 and using one of outputs to trigger whatever circuit or function. I think supply current is 'high' for battery-powered circuits.
 

danadakk

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Schottky diode with low Vfwd, what is your load current ?





Regards, Dana.
 
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d123

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Hi,

Not so simple parts-count wise, but as precise as might be desirable - Op amp clamp used to drive homebrew LDO. Or maybe op amp + adjustable Vref + MOSFET constant current source circuit used to limit Vout to 4.1V.

Vref (or Vref driving resistive divider) + comparator(s) is more configurable homemade version of LM3914 with much lower Iq.
 

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