@jmarcelino Was the battery type (Li-Ion) anywhere documented regarding the charger chip? That all should be by the vendor. I would probably combine the expansion board electronics with the LiPo Rider Pro. But I don't like to put too much unnesecary chips onto the board. I am not yet aware of charger and protection circuits (as discussed in my other thread https://forum.pycom.io/topic/1671/expansion-board-lipo-save-power-down-function-so-save-lipo-undervoltage) Assembling these two boards and connecting them with another USB cable is ok for prototyping, but nit ok for a end product - so to say :-) What about a KiCad project on github? Collecting circuits for various aspects? And documenting application notes for combining them into new ones? Btw, I have ordered three ADS1115 4 channel 16 Bit converters to monitor these voltages. It get's an interesting project... What is not yet clear to me is the fact that batteries probably have their own undervolt protection, that could nock out the remaining circuit so that it stops recharging in an undervolt situation, if not properly designed. So for my experiment, could I put the Seeed Studio Lipo Rider Pro battery connector in parallel to the expansion board battery connector and put there then the battery? If that is possible, I could keep switched off the step up converter for the USB port on the Lipo Rider and save me a USB cable :-)