Battery/Starter Straps

Battery and starter straps are the short, heavy-gauge leads that carry the high current between the battery, starter, earth and isolator on a vehicle. This guide explains the types and how to choose.

What they do — Unlike thin signal wiring, these straps carry the heavy current a starter motor draws, so they use thick cable with a crimped lug at each end for a secure, low-resistance connection. A poor or undersized strap causes voltage drop, slow cranking and heat, so they are built for the load.

The main types — A starter strap connects the battery to the starter or solenoid to carry cranking current. An earth strap connects the battery negative to the chassis or engine to complete the circuit and provide a solid earth. A switch or isolator strap links the battery to a battery isolator or master switch. Choose the strap for the connection you are making.

Positive and earth — Positive straps are usually red and earth straps black, so match the colour and terminal to the post or stud at each end. Check the terminal type on each end suits your battery post and the stud or clamp it bolts to.

Choosing length and rating — Pick a strap long enough to route neatly without strain, and rated to carry the current for the job. If in doubt on cable size, match or exceed the original strap rather than going thinner.

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