Battery and Motor Cables

The high voltage cables carrying current from the battery pack to the motors will be discussed here.

• Flexibility

  • These cables will likely be moved around, plugged in, unplugged, etc. many times during debugging and testing. This means we need a high strand count in the cables.

• Gauge

  • The wires must have sufficiently low resistance in order to minimize the resistive power losses and increase the efficiency of the drivetrain. We have selected a minimum of 4AWG (25mm2) for DC battery and 6AWG (16mm2) for DC motor controller wires. Motor phase output wires should be no larger than 16mm2 (10mm outer diameter) to fit in the motor controllers)

• Color

  • We will keep all high voltage cable ORANGE, as the recommended industry standard (recommended by SAE, though I can’t find the document). Black or red heatshrink will be used on the ends of the wires to denote positive and negative high voltage wires.

• Shielding

  • MSXII did not have shielded HV cables, and no significant issues were observed (after switching to differential communications). I would love to do more research into this, but for now we will stick with non shielded wire.

• Insulation

  • Concerns with PVC insulation - it will slowly pull back from the connector over time, as it does when soldering

  • Crosslinking and irradiation explained here: https://chargedevs.com/features/cable-sizing-and-selection-for-ev-systems/

  • We will go for crosslinked, irradiated insulation, per the recommendations from Champlain Cable:

For reference, I believe that most welding cable is EPDM insulation.

Tritium Cable Recommendation:

This is essentially double insulated welding cable.

IEWC Part Numbers:

32102862

Huber + Scuhner 16mm2 1kV XLPO (Crosslinked polyolefin), double insulation

Champlain Cable:

EXRAD--HVFXI-16 (or 20)

EXRAD-XLE6-6X (or 4X)

EXRAD-FXIF-16 (or 20)

EXRAD-FX-6XX (or 4XX)

We would love for IEWC to provide recommendations or a call on speccing wires, and see what they have available.

Good discussion on cable lugs and why speccing the proper one for the type of cable you have is important - finer strands will lead to a physically smaller cable, so a proper flanged or bellmouth lug is required.
https://www.solarpaneltalk.com/forum/off-grid-solar/off-grid-solar-panel-systems/351593-is-welding-cable-suitable-for-battery-systems

Also be sure to use silicone grease on the copper cables to prevent oxidation.