Purpose

To meet regulations 9.4 in the ASC regs: https://www.americansolarchallenge.org/ASC/wp-content/uploads/2024/10/FSGP2025-Regs-RevA.pdf

Seven light locations on the car.

Front L/R: white daytime running lights, amber turn signals

Side L/R: amber turn signal only

Rear L/R: red brake light, amber turn signal

Canopy: red brake light, white BPS fault indicator

Current solution

Every lighting board has (about, red has anode/cathode flipped) PCB with just the color of LED swapped during assembly.

Powered by 12V from Power Distribution on 4pos microfit connector, each colour connected in series with a resistor for current control.

Problem

To achieve the required brightness, the light is getting too hot. To fix this we need to investigate alternative current limiting approaches.

Investigate using a proper LED driver, this would also solve the problem of light output changing with exact input voltage (our 12V is actually 10-15V).

Step 1: Determine current light output, for this you can assume exact 12V input and equate current directly to light output.

Step 2: Spec LED driver, take a look here Integrated Circuits (ICs) | Power Management (PMIC) | LED Drivers | DigiKey Electronics - note that “linear” regulators are just fancy resistors, so they will not solve the heat issue. Don’t get ones that requires microcontrollers

Step 3: Implement LED driver in new light schematic. This is only really needed for the daytime running lights, so only focus on the “tub” lights. This is because the other lights, ex. turn signals, are not on for enough time for heat to be an issue.

Notes

Current:

White: 31.5 mA

Red: 81 mA

(should be able to support 80 for both, then just dim them if not)

Linear Regulator:

BCR430UXTSA2 | DigiKey Electronics

Switch Regulator:

TPS92200D1RXLR | DigiKey Electronics