Custom Electric Racing Go-Kart Build (Bons V1) - Wiring & Safety Review (72V / 340A)

[BonsDNB]

Hello everyone!

I’m moving into the final assembly and wiring phase of my custom electric racing go-kart build ("Bons V1") and I’ve put together a detailed wiring schematic. Before I start crimping and final assembly, I’d like to run my plan by the community to ensure everything is safe and optimized.

Core Specs:

• Motor: QS180 90H 8kW Encoder Mid-Drive
• Controller: Fardriver ND721800B
• Battery: 72V Custom pack (Molicel P50B)
• BMS: ANT Smart BMS (340A Continuous / 850A Peak)
• Protection/Control: 400A MEGA Fuse, Main Contactor (with 100Ω 25W pre-charge resistor), E-Stop (NC), LANBOO Key Switch, 5A Inline fuse for the logic loop.
• Telemetry: DKD LCD Display, TF03K Coulomb Counter (with shunt).

My Wiring Schematic:

Segment 1: High Voltage Path (Main Power)Battery (+) -> 400A MEGA Fuse -> Main Contactor (with pre-charge resistor) -> Fardriver (B+)Battery (-) -> TF03K Shunt (B-) -> Shunt (P-) -> Fardriver (B-)

Segment 2: Ignition & Control Loop (72V Logic)Tap from MEGA Fuse output -> 5A Inline Fuse -> E-Stop (NC) -> LANBOO Key Switch (NO) -> Distribution point:

1. Contactor Coil (+)
2. Fardriver Ignition (E-lock) pin
3. DC-DC Converter (72V->12V)
4. DKD Display (72V in)

Segment 3: 12V NetworkDC-DC 12V output -> 10-Way Blade Fuse Box (with warning indicator). From here, I am distributing power to lights, TPMS, USB, etc., with all 12V grounds returning to the DC-DC 12V GND. (Isolation maintained: no 12V grounds touch the main battery ground).

Segment 4: SensorsSiaecosys ATV Hall Throttle and 0-5V Brake Pressure Sensor wired directly to Fardriver signal pins.

The Goals & Questions:

1. Current Limiting: I've decided to set the Fardriver Max Line Curr to 340A (matching the BMS continuous rating). I'm leaving the BMS 850A peak as safety headroom for transients. Does this align with best practices for the ANT BMS?
2. Grounding/Shunt: Is my approach of running all negatives through the TF03K shunt P- side correct, or should logic grounds return directly to the battery/Fardriver to avoid potential interference?
3. Contactor Control: Is it safe to trigger the Main Contactor coil directly from the ignition switch split, or should I use the ignition to trigger a smaller auxiliary relay for the contactor coil to take the load off the key switch?
4. Any Red Flags? I’ve carefully separated the thick HV cables (rear zone) from the signal/logic harness (front zone) to avoid EMI. Given the high phase currents (planning 700-850A phase), are there any specific precautions I should take to protect the encoder sensor signal?

I’m really aiming for "track-ready" reliability here. Any tips, critiques, or "I wish I knew that before I built mine" advice would be incredibly helpful!

Thanks in advance,
Bons