The following is extracted from the Bentrider thread "Electric Assist for Trice Q":
The custom light strip is a "Turns and Brake Flexible Array" from Radiantz. The strip has a 9" (230mm) long red section in the middle that is dual brightness - bright for brake and dimmer for running. Each end has short segments of amber LEDs for turn signaling. The overall length is about 13" (330mm).
The horn is a cheap $4.00 stud mounted with a spare reflector mounting bracket.
Reed Switches for brake shutoff are the Meder Electronic type MK6-6-C, DigiKey part number 374-1065-ND.
The handlebar switch for lights, horn and turn signals is part number SWT-30 from ElectricScooterParts.com.
The turn signal flasher is a special low-current version for LEDs. It is part number ELFR-1 made by Custom LED Signals.
The DC-DC converter ordered is a 100W (7A) 36-75V In, 12V Out Power One part number SSQE48T07120-NABNG. It is no longer available but there are similar alternatives. Voltage for the nominally 8V P7 flashlight is provided by a Castle Creations BEC.
The relays used were a mixture of 12VDC coil relays from various sources. The only double pole is the brake relay which activates both the brake light and the throttle cutoff.
In this particular case, the total current draw with all 5 relays activated is 142mA. The current draw for all the lights at 12VDC maxes out at about 2A with a strong P7 headlight.
Most connectors used are Deans Micro 2 and 4 pin polarized. These are very small connectors good for currents up to about 10A.
The enclosure is a typical project box with mounting flanges.
Before receiving the DC-DC converter, I used a 3s LiPo for the lighting system without the DC-DC converter.