Photonicat 2 LED Indicator

Photonicat 2 has a single two-colour indicator LED (red + green). Yellow/orange is produced by lighting both colours together; there is no blue.

The indicator follows a MacBook-style scheme:

• Colour tells you the charge state — 🟠 yellow = charging, 🟢 green = charged.
• Motion tells you the machine state — breathing = system running, steady = system off.

Applies to firmware RA2E1260726001 and later. Earlier firmware did not distinguish system on/off while charging or charged.

中文版见 Photonicat 2 LED 指示灯. For buzzer tones see Photonicat 2 Sound Guide.

Quick reference

The animations below are illustrative; their timing matches the firmware (5.84 s breathing cycle, 2 s heartbeat).

Animation	Indicator	Meaning
	🟠 Yellow, breathing	Charging, system running
	🟠 Yellow, steady	Charging, system off
	🟢 Green, breathing	Fully charged (or at charge limit), system running
	🟢 Green, steady	Fully charged (or at charge limit), system off
	🟢 Green, heartbeat pulse	Running on battery, charge level normal
	🔴 Red, flashing	Low battery (below 6500 mV — see Low battery red light)
	⚫ Off	Idle on battery, system off

Full state table

Battery thresholds are firmware defaults and can be overridden by the host. Values are for the 2S pack: full 8280 mV, low warning 6500 mV, minimum boot 6600 mV, hard shutdown 6300 mV.

Power level	Charger	Animation	Colour	Pattern	Timing
Charging, any level	Connected		🟠 Yellow	Breathing (system on)	2.8 s up / 2.8 s down / 0.24 s off, ≈5.84 s cycle
Charging, any level	Connected		🟠 Yellow	Steady (system off)	Constant
Full, or at charge limit	Connected		🟢 Green	Breathing (system on)	Same 5.84 s cycle, after 10 s delay
Full, or at charge limit	Connected		🟢 Green	Steady (system off)	Constant, after 10 s delay
Below 6600 mV, DC ≥ 8 V, no charge current	Connected		🟠 Yellow	Steady	Constant
Above 6500 mV, system on	None		🟢 Green	Heartbeat pulse	2 s period
Above 6500 mV, system starting	None		🟢 Green	Steady	Constant
Above 6600 mV, system off	None		🟢 Green	Steady	Constant
Below 6500 mV, system on	None		🔴 Red	Continuous flashing	1 s on / 1 s off, begins after 60 s, until the voltage recovers
Below 6500 mV, short press	None		🔴 Red	Flicker	1 s on / 1 s off, while held or until the voltage recovers
Charger removed, system off	None		⚫ Off

Service and transitional states

These override the states above.

State	Animation	Colour	Pattern	Timing
Shutting down		🟢 Green	Blink	≈0.5 s on / 1.5 s off
Firmware download mode		🟠 Yellow	Fast blink	≈0.5 s period
Reset / factory restore mode		🟠 Yellow	Slow blink	≈1 s period

Low battery red light

When the battery runs low the indicator turns 🔴 flashing red. This is the only situation in which red is used.

Item	Detail
Trigger	Battery below 6500 mV (2S pack, about 3.25 V per cell) with no charger connected
Rhythm	1 second on / 1 second off
Repeats	Flashes continuously until the voltage recovers or a charger is connected
While running	Starts only after the voltage has stayed below the threshold for 60 seconds
Short press	With a low battery, a short press of the power button triggers the red flashing immediately (after a 0.5 s debounce)
Effect on green	The green heartbeat stops while red is active; the two never show together

⚠️ Important

• The red warning keeps flashing until the voltage recovers or a charger is connected; it does not stop on its own. (Firmware before RA2E1260726003 flashed only 3 times and then went quiet.)
• The red threshold (6500 mV) is only 200 mV above the hard shutdown point (6300 mV). That is a very steep part of the 2S li-ion discharge curve, so connect a charger promptly once you see red.
• The trigger is voltage, not a percentage. Under heavy load the voltage sags and the warning can appear while a useful charge remains; when the load drops the voltage recovers and the warning stops.

Charge limit

If a charge limit is configured (for example 80 %), the charger is switched off once the pack reaches it. Charge current drops to zero, so the device treats this as fully charged and shows 🟢 green. The pack then powers the load and slowly discharges until it falls below the resume threshold, at which point charging restarts and the indicator returns to 🟠 yellow. Each transition is delayed by about 10 seconds.

Notes

• Breathing runs at a lower peak brightness (25 % duty) than steady (50 %), so a breathing indicator looks dimmer than a steady one of the same colour.
• 🔴 Red is only ever used for low battery, and keeps flashing until the voltage recovers or a charger is connected.
• The indicator can be disabled entirely through the host protocol, in which case it stays off in all states.
• For how the charge level behind these indications is computed, see Photonicat 2 SOC Calculation.