Reducing Li-Ion battery voltage

[jzeds1491]

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]

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]

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]

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]

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

https://www.infineon.com/dgdl/Infineon-BAT60ASERIES-DS-v01_01-en.pdf?fileId=db3a304313d846880113def70c9304a9

Lowest voltage drop diode possible

I am harvesting energy from an NFC device using a tuned antenna on my PCB. Through this method, I am able to generate about 3.05V. I would like to charge a super capacitor using the power harvested...

electronics.stackexchange.com

https://datasheets.maximintegrated.com/en/ds/MAX40203.pdf

Regards, Dana.

 

[d123]

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.