How do you wire the battery isolator relay?

One of the relay’s 6.3 mm terminals is connected to D+ (alt. 61 or STA) or to the appropriate terminal on the ignition switch. (On the ignition switch, use the terminal that has voltage when the engine is running, but not when the engine is switched off.) This wire controls the relay.

The other terminal is connected to the starter battery negative (−). Preferably use a 2.5 mm² cable or larger.

All connections on the relay are polarity‑independent, meaning there is no risk of connecting the relay or its control circuit “backwards.”

You can therefore choose freely which terminal to use for positive and negative.