voltage drop with bh1750fvi ?

  • i create a lightsensor sketch with bh1750fvi, i found when power with CR2032, voltage from 2.9v drop to 2.4 or lower, but bh1750fvi required 2.4V, so sensor node can't continue , but later 3-5 seconds voltage recovery to 2.9v

    ATMEGA328P-U-TH+ nrf24l01-smd with Customized PCB, Are there any good suggestions for solving this problem? thanks!

  • @huex try with new battery

  • @rozpruwacz yes,but new battery also drop 0.4-0.5v like this ,😥 , this is new battery offer by Two weeks ago., use it on si7021 node,work well, so 。。。。

  • Mod

    @huex said in voltage drop with bh1750fvi ?:


    Supply current of this sensor is 190uA, sleep current only 1 uA. Are you sure this sensor is put to sleep when not operating it (when your node is sleeping)?
    Are you using a GY-30 module? These seem to have a voltage regulator on board to support 5v supply levels. Try to bypass this regulator when powering from batteries.

  • @Yveaux thank you ,

    i create a pcb with bh1750fvi chip,

    i use multimeter measure bh1750fvi v+ pin and gnd ,when power on battery from 2.9v drop 2.1v ,and 3-5 seconds ,up to 2.9v, use a new battery NANFU cr2032, also 3.1 drop to 2.7v,

    sleep all is ok , when sleep 7.3ua

    but, when down 2.4v bh1750 no work....so。。。i don't how to do,

  • Hardware Contributor

    coincell internal resistance is higher than others batteries.
    so when your mcu is not sleeping or waking up, you'll get voltage drop (even a few mA drained by mcu will drop voltage like you noticed)

    To fix voltage drop and extend lifetime:

    • use good brand coincells (significantly better specs and lifetime than nonames)
    • add a few(2-3) 100uF close to battery pins for buffering, you can even add one close to the radio module.
    • use wait() or sleep() in your sketch before reading your sensor (to allow voltage recover)
    • you can also use 1Mhz clock for mcu, to use less power when it's not sleeping
    • use a sensor with better voltage range
    • and so on..

  • @scalz
    ok ,thanks , i follow your suggestion to Give it a try,,thank you ,👍

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