Bottom LED blinking once per second indicates what?

• A. Temperature high
• B. Battery almost depleted
• C. Sensor fault
• D. Unit rebooting

Answer: (B)

A bottom LED blinking once per second is a power-status cue. That steady, gradual blink pattern is commonly used to signal that the battery is almost depleted—the device is running on low power and needs replacement or recharging soon. It’s chosen because it’s clear and easy to notice, even in outdoor or high-noise environments.

Other states typically produce different signals: overheating or temperature warnings usually show a different pattern or color to prompt immediate action on temperature, a sensor fault would indicate a fault condition rather than a routine power alert, and a rebooting unit follows a startup sequence that isn’t a regular single-second blink. So the one-second, regular blink best points to low battery.