BLUF: I’m trying to understand how the Electron senses and reports State of Charge (SoC) to the Particle console.
It appears from this thread that there is a “fuel gage” chip integrated into the electron that performs the measurement task. Does this just do a measurement of the voltage of the battery and then interpolate based on a given LiPo battery type voltage discharge profile?
Reason I am asking is because I made an adapter for power tool batteries with a buck converter so that the Electron can be powered from one. I suspect then, it will always report the corresponding battery percentage to whatever the buck converter voltage output correlates to… meaning I won’t be able to know SoC of the power tool battery… meaning, I’d have to figure out a way to hack into the comms/clock leads on the battery and interpret the data (which I bet someone more steeped in the field has already done).
Simple answer - yes. There is some debate about the meaning of a %charged level - for LiPo batteries I tend to report 5 states (Charging, Fully charged, Nominal, Charge required, Empty).
I made an adapter for power tool batteries with a buck converter so that the Electron can be powered from one. I suspect then, it will always report the corresponding battery percentage to whatever the buck converter voltage output correlates to… meaning I won’t be able to know SoC of the power tool battery
Correct, you might be able to tap into the monitoring circuity on the power tool or use a battery monitor board or just measure the voltage put it through a voltage divider (to get a range 0-3.3V) and then read with analogRead(). But be careful you don't distort the measurement so best to use a unity gain amp or voltage follower that provides an infinite impedence.