Power Down Reset

Just started testing a device powered off a LiFePo battery instead of a VRLA - occasionally seeing the Photon reset - it is reporting this as POWER_DOWN reset however looking at the Vin to ground on the Photon with a DSO - not seeing any difference between it resetting and normal - i.e. no voltage drop out from 5V. Haven’t measured the current. Any one have any clues about what this reset cause and actual reason might be? Device OS 1.4.4 is being used.

Take a look at the 3.3V rail going to the uC. Could be something goofy.

Like what sort of goofy thing? 3V3 is used to power an SD card and connected to VBAT. Never had an issue like this before.

Unknown. But if you can’t detect a spike on 5V, can you detect it somewhere else? Can’t investigate something you know nothing about.

(This is basically a “challenge your assumptions, test more” prompt)