[Solved] Solar Charging a LoPy



  • Hi
    I have a LoPy on the pycom expansion board with a LiPo attached to the battery plug.
    Now i would like to charge the LiPo with a solar module. But it's unclear to me where to attach. Is the +5V on the pycom expansion board a suitable input? or do i have to cut a usb cable and attach the solar module to the USB port?

    Thanks to all the Replies

    Summary:

    • The 5V VIN on the pycom expansion board is NOT usable for charging a battery on the battery connector
    • a powerfull 5V charging source can be connected to the USB connector and the LiPo or NiMH on the battery connector get's charged
    • for a "weak" source like a small solar panel you have to build your own "charger"

    Solar Charging:

    • a very good hint form @jmarcelino is to use a TI BQ25570 energy harvester chip to connect a solar pannel to different kinds of batteries/accumulators


  • I've been running the SiPy from a $7 solar panel into a TI BQ25570 energy harvester chip and supercap bank.

    Hope to get some time to write about it soon.

    I don't have data to back this so take it as is , but using the expansion board for this seems very inefficient to me.



  • I do the test with Lipo batterie 1200mAh and solar panal 5V , 450ma, and it works the whole day, but I have some trouble sometimes to swap directly to lipo, and I may be lipo was discharging !



  • @jmarcelino Many thanks for clarification, so let's cut that USB cable then :-)



  • @roadfox

    i would like to charge the LiPo

    somehow i omit that you mean charge LiPo not power Lopy throught.



  • @livius said in Solar Charging a LoPy:

    @roadfox
    First - you cannot attache solar panel direcly - you must use some regulator
    and i link it for you in below post -there is solutoion for 3V3 pin. You can use VIN but max 5.5V if i remember corecly.

    To Charge a LiPo you need a higher Voltag than the Cell so i doubt that i can charge my 3.7V ratet LiPo with 3.3V

    Without regulator you can have e.g. 7V on your solar panel and this damage your Lopy.

    My "regulator" consist of a 5V Z-Diode, that protects the expansion board from overvoltage



  • @roadfox
    No, feeding 5V through the 5V pin on the expansion board will not charge the battery because that comes after the autoswitching power mux (which does reverse voltage blocking)



  • @roadfox
    First - you cannot attache solar panel direcly - you must use some regulator
    and i link it for you in below post -there is solutoion for 3V3 pin. You can use VIN but max 5.5V if i remember corecly.
    Without regulator you can have e.g. 7V on your solar panel and this damage your Lopy.

    But someone can correct my answer if i am wrong here.



  • I cannot find an answer to my question on this thread. To me it's still unclear if a can feed the 5V for charging the LiPo trough the VIN pin on the expansion board or if the charging Voltage HAS to be fedd over the USB connector.




Log in to reply
 

Looks like your connection to Pycom Forum was lost, please wait while we try to reconnect.