May 2025 to Fall 2025
Accessory electrical architecture work for SARIT research vehicles, including reverse detection, power rails, and diagnostic limits around the ASI BAC2000 motor controller.
![[sarit electrical panel]](/assets/[sarit-electrical-panel].jpg)
Added SARIT electronics around a stock 48V vehicle architecture that was not originally built for research accessories.
Quick Read
- Worked on accessory power questions while supporting camera, hitch, and power-delivery projects.
- Documented the 48V, 12V, and 5V power rail structure.
- Helped reason through reverse detection for buzzer and camera switching.
- Investigated limitations around ASI BAC2000 controller access.
- The main constraint was adding research electronics to a vehicle that did not originally provide clean accessory infrastructure.
System Need
Every added SARIT technology needed power.
That included cameras, displays, telemetry, pedestrian detection hardware, reverse buzzer behavior, and future sensors.
The stock vehicle electrical system was built around the drivetrain, not research accessories.
Power Rails
The working architecture used three main rails.
- 48V traction rail: battery, main solenoid, ASI BAC2000 motor controller.
- 12V accessory rail: headlights, horn, relay coils, user-facing accessories.
- 5V logic rail: ESP32 telemetry, hall sensors, GPS, and signal electronics.
One important issue was that an earlier 12V converter configuration stayed live even with the key off because it was wired before the solenoid. That made it a possible contributor to parasitic drain.
Reverse Detection
The SARIT did not have a clean built-in reverse signal output.
The team needed reverse detection for two things:
- Triggering a reverse buzzer.
- Switching the display to the rear camera view.
The solution was to tap the signal path between the handlebar forward/reverse switch and the ASI motor controller.
The voltage change was too small to drive a relay directly, so a custom amplifier circuit boosted it enough to switch a relay.
That relay could then trigger the buzzer and camera display behavior.
ASI BAC2000
The SARIT drivetrain uses an ASI BAC2000 motor controller.
It is capable hardware, but the normal BACDoor configuration software requires OEM or authorized dealer access.
That limited what the research team could inspect or change.
Without full controller access, some diagnostics became harder:
- Internal controller state.
- Regenerative braking parameters.
- Whether startup current behavior was normal or a fault.
- Low-level drivetrain settings.
A read-only ASI monitoring app provided some diagnostic visibility without full OEM credentials.
What I Would Improve Now
I would document the accessory electrical architecture as a formal interface earlier.
Mechanical projects kept crossing into electrical constraints. A shared interface document would have made camera, buzzer, telemetry, and power work easier to coordinate.