Quote Originally Posted by babooon View Post

....................................... I was hoping that this would be a simple job of connecting a new battery, open to any (low cost) ideas to make this a safe and usable system.

Cheers.

.
Simple, leave it alone, change nothing its 'perfect'

KISS, remember that old adage ? keep it simple stupid (no offense ). No bull****, complex, failure prone or expensive electronics. You have a simple, cheap and effective dual battery system that automatically couples both batterys when the engine is running and isolates when the engine is turned off regardless of the position of the ignition key or any other switch. It doesn't get any better than this

Certainly ensure both ends of the battery coupling cable are adequately fused (or circuit breakers fitted) and insulation/connectors are in good condition but the setup (using a separate oil pressure switch) is perfect for your vehicle or any other vehicle with a simple non computer controlled alternator and lead acid batterys.

Deano