wiringharness.coBattery Harness (EV) — Design and Build Guide
What is it?
A battery harness is the high-voltage wiring system in an electric vehicle that connects the battery pack to the rest of the powertrain. It carries DC power from the battery to the inverter, onboard charger, DC-DC converter, and any auxiliary high-voltage loads like an electric AC compressor or PTC heater. These harnesses also include low-voltage signal wires for the battery management system (BMS) that monitor individual cell voltages and temperatures.
What's included
A complete battery harness includes high-voltage DC bus cables rated for the pack voltage (typically 400V or 800V), BMS cell tap wiring for voltage and temperature monitoring, safety interlock loop wiring, pre-charge circuit connections, HV disconnect and service loop provisions, and shielded signal cables for current sensors. It also includes orange-jacketed HV cables per automotive standards and properly rated HV connectors with HVIL (High Voltage Interlock Loop) features.
Common applications
- DIY EV conversions using salvaged Tesla, Leaf, or Chevy Bolt battery modules
- Custom electric race cars and drag cars with high-discharge battery packs
- Electric UTV, go-kart, and small vehicle builds
- Solar and off-grid battery storage systems using automotive-grade cells
- Electric boat conversions with marine-rated HV wiring