Aftermarket Sub-woofer Amplifier Installation using DC-DC +12v Power Source

[hamtonp]

Question: one concern I have with the circuit with the resistor is the size of the wiring for the 30A relay. The 4 gauge wiring (power) going to 12 gauge (relay) back to 4 gauge doesn’t seem to make sense. Any thoughts?

I'm using a huge solenoid to act as a relay and using 6 gauge wiring throughout. I think I may be overkilling it a bit.

BIR200 200-Amp Relay and Battery Isolator

Product Details: Mobile Audio Relay and Battery Isolator Great for isolating a second batter making it dedicated to the stereo system Does not create a voltage drop to the second battery like conventional isolators Lengthens battery life by preventing your two batteries from charging and...

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There are smaller versions:

BIR80 80-Amp Relay and Battery Isolator

Product Details: Mobile Audio Relay and Battery Isolator Great for isolating a second batter making it dedicated to the stereo system Lengthens battery life by preventing your two batteries from charging and draining each other Does not create a voltage drop to the second battery like...

nvx.com