I am looking at possible fault conditions with my Photon which is powered from a ‘12V’ battery, via the Relay Shield.
If the battery is connected backwards, it is clear that the Relay board won’t mind, but I also have a divider which monitors the battery voltage via Photon pin A0/PC5. With a reversed battery, the Photon will be powered down and A0 could see up to -3.3V through 796 Ohms. That seems to imply that the maximum (negative) current under those conditions will be -3.75 mA. I am hoping that, being under 5mA, there won’t be any damage, but would like to hear from someone who knows for sure.