Quick answer: establish when and how the light fails
A light that is dim from switch-on, one that turns off halfway through the night, and one that never switches on need different checks. Start with the operating schedule and controller records, then distinguish energy shortage, a protective shutdown and a luminaire or wiring fault.
Use the controller and battery manuals for the exact model. A qualified technician should isolate circuits and perform electrical tests using the specified sequence, instruments and protection. Do not bypass the BMS, connect an LED module directly to a battery, or use a generic charger or voltage threshold. Stop using a damaged, swollen, leaking or unusually hot battery and arrange service.
1. Classify the symptom
| Symptom | Checks to prioritise |
|---|---|
| Dim immediately after sunset | Scheduled dimming, controller mode, battery condition and output status |
| Normal initially, then off early | Recorded energy use, cutoff reason, BMS state and charging history |
| Never switches on | Night detection, enable command, controller error and output circuit |
| Several nearby lights fail together | Shared weather, changed settings, shading or commissioning configuration |
| Only one unit fails | Local panel condition, connections, battery and luminaire faults |
2. Confirm the night profile and sensor behaviour
Check whether the present brightness is the configured level. Time-based modes may run from sunset or a clock, and motion modes can reduce light when no activity is detected. A changed clock, mode or enable command can resemble a hardware failure. Compare the actual model manual with the saved settings before altering them.
Nearby lighting or an incorrect day/night input may influence switching. Use the manufacturer-approved diagnostic mode; do not disconnect live solar wiring or defeat a safety interlock to simulate darkness.
3. Read the shutdown reason
A low-energy cutoff, battery temperature restriction, overcurrent event or controller fault should be investigated according to the recorded code. Do not repeatedly reset the unit or disable its protections. LiFePO4 voltage has a relatively flat operating region, so a single reading is not sufficient to confirm remaining usable energy.
4. Compare charging and consumption
Check the preceding days of solar input, panel shading and contamination. Compare the measured night profile with the original energy calculation. Include communication equipment, heaters and any new accessories. If the unit gradually runs for fewer hours after poor weather, investigate the energy balance and recovery time before replacing the LED assembly.
Use the daytime charging diagnostic guide to check the charging side and the backup calculation guide for the energy budget.
5. Check the luminaire and output circuit
If the controller indicates that the output is enabled and the energy supply is adequate, a technician should inspect the output circuit, connectors and driver using the service procedure. LED modules may require a current-controlled driver; direct battery connection can damage the module and invalidate the diagnosis. A replacement must match voltage, current, connectors, polarity and control interface.
Verify the repair
- Restore only the approved configuration and record what changed.
- Confirm switch-on, the intended brightness transitions and the controller status.
- Observe a complete night, then compare charging and operation over the next relevant weather cycle.
- If the fault recurs, retain the codes and time-stamped logs instead of repeatedly resetting the system.
Information for a support request
Include model labels, the exact failure time, controller/BMS codes, brightness schedule, weather, installation photographs and charge/load records. State whether the problem affects one lamp or the whole site.
Contact MCL Solar for model-specific support · Battery selection and operating limits.