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.
Since RA2E1260731011 the charging orange is warmer (R60 %/G24 % instead of R55 %/G35 %), the breath fades only to a dim-orange floor (≈1/12 of peak) before the valley off — on earlier firmware the dim ends of each breath cycle could look pure red — and the valley off hold is 0.5 s instead of 0.24 s (cycle ≈6.1 s).
Since RA2E1260802000: trying to power on with a flat or too-low pack flashes red three times immediately (earlier firmware showed nothing, so a flat device looked bricked), and a short press while off with a low pack shows the same three flashes. Continuous red flashing is only used while the system is running. The power-button long press is now 1.5 s.
Fixed in RA2E1260805000: on RA2E1260802000–RA2E1260802001 a short press while the device was off in standby could flash red three times even with a full battery — the voltage sensor briefly reads 0 mV while waking from standby and this was miscounted as low battery. Red now requires a genuine low-voltage reading.
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 (≈6.1 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 / 0.5 s off, ≈6.1 s cycle; fades to a dim-orange floor (≈peak/12), never pure red |
| Charging, any level | Connected |  |
🟠 Yellow | Steady (system off) | Constant |
| Full, or at charge limit | Connected |  |
🟢 Green | Breathing (system on) | Same ≈6.1 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 (valid reading), short press, system off | None | |
🔴 Red | Flicker | 1 s on / 1 s off, 3 flashes, first flash immediate (0.5 s debounce) |
| Below 6600 mV, long-press power-up refused | None | |
🔴 Red | Flicker | 3 flashes, first flash immediate |
| 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 | System running: flashes continuously until the voltage recovers or a charger is connected. System off (short press or refused power-up): exactly 3 flashes, then the device goes back to standby |
| 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 flashes red three times immediately (after a 0.5 s debounce). A 0 mV sensor warm-up reading right after standby wake does not count (since RA2E1260805000) |
| Effect on green | The green heartbeat stops while red is active; the two never show together |
⚠️ Important
- While the system is running, 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.) While the system is off, short press and refused power-up flash exactly 3 times so the MCU can return to standby.
- 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
- Green breathing peaks at 25 % duty while steady green is 50 %, so breathing green looks dimmer than steady green. Orange breathing peaks at the same R60 %/G24 % mix as steady orange.
- 🔴 Red is only ever used for low battery. While the system is running it keeps flashing until the voltage recovers or a charger is connected; while off it flashes exactly three times.
- 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.