Adding second battery, need bulkhead connector for cables?

HMS Beagle wrote:
The Pollak connector in the OP (or the philips equivalent) is what I used. It is normally called a "liftgate" connector at truck suppliers. A nice robust connector.

I also use these for the heavy charge line from the truck . It works great and are available at NAPA and online . However , they will only accommodate up to 4 ga wire . If the OP is going heavier wire he should probably use something else .