Electron Charging LED flashing @ 1 Hz

Hi there. I am in the process of setting up 100 devices containing Particle Electron boards. I left 32 of them charging overnight. This morning, on around half of them the charging LED was off but, on the other half, the charging LED was flashing at about 1 Hz. Can anyone tell me what that means? I imagine it’s not good…


No idea about the reason, but that’s what it is

Ah, yes, safety timer. We are doubling up on batteries (yes, I know, we’ve checked that the short-circuit and current protection in the battery is sufficient for this) and so a charge from close to empty hits the guard timer. Unplugging and plugging back in the USB cable allows it to begin again.