Temperature
The LEDs used for the lights can get very hot very quickly. It is important that the temperature of the lights stays within limits that will not interfere with the functionality of any nearby circuits, and will not pose a safety hazard.
Below is a graph displaying the temperature of revision 3 of the tail light prototypes over time.
A temperature probe was used to measure the temperature. PWM was at approximately 50% duty cycle. No enclosures were used during testing.
The temperature stabilized at around 47 C after approximately 15 minutes.
Next steps would include testing the lights in an enclosure.
Voltage Boost
Since a boost converter is used in the driver board, a boost in output voltage is expected.
Voltage boost changes depending on PWM duty cycle (which can be adjusted with the potentiometer).
Here are the results for voltage boost and supply current as a function of duty cycle. The power supply was set to 12 V.
Duty Cycle (%) | Voltage Boost (V) | Supply Current (mA) |
|---|---|---|
<1 | -0.503 | 170 |
15.14 | -0.494 | 170 |
44.05 | -0.429 | 175 |
72.24 | 0.077 | 295 |
88.17 | 0.273 | 360 (recommended current is 350 mA) |
Very high (>99) | 0.398 | 410 |
Burnt out LED
When a single LED was removed, the remaining LEDs were fully illuminated at approximately 3V. Constant current mode was activated on the power supply, current was approximately 250mA.
Brightness
-To do