Engine Battery to House Battery Wiring

[Toedtoes]

I thought I'd share this mod with everyone.  My "wonderful" (don't let him know I said that) boss is helping me modify the engine battery to house battery wiring.

Currently, the wiring is EXTREMELY undersized for the task (maybe a 14 gauge - should be 4 gauge) and when you start the engine, the system immediately starts charging the house battery (pulling from the engine battery that is trying to start).

So, we are replacing the old wiring with 4 gauge and adding a few things.  Attached is a diagram of the plan.  Basically, we are adding a double pole double throw on-on switch on the dash and wiring that to delay circuit and then to a solenoid relay.  Then we are running the 4ga wire from the engine battery positive to a 300 amp circuit breaker to the solenoid to a 300 amp circuit breaker to the house battery positive. 

For normal situations, when I start the engine, the connection to the house battery will be blocked for the first 30 seconds or so  - just enough time for the engine to kick in.  Then the delay circuit will kick in and the house battery will charge from the alternator.

The trick is that if my engine battery doesn't have enough juice to start the engine, I flip the switch and the system pulls power from the house battery to jump start the engine battery!

We're adding two LED indicator lights with the switch - green to show that the normal setting is working properly; and red to remind me I'm in the jump start mode.  In addition, by adding the circuit breakers at both ends, I protect both batteries from getting blown up by bad wiring, etc.

We'll be doing this in the next couple weeks.  Cost will be under $200 for everything.

[Clipper Joe]

Hi Toedtoes,
This Should Be A Real Helpful Upgrade For Your Rig.

I'm Not Sure, On Wilson, There Is A Isolation Relay Already Built In To The Dodge Wiring Circuit.
Beside The Grounding Lug. Power Comes From Battery Pos.Dc To  Relay Then Fused & #8 Ga. Wire To Rear House Batteries Then To Battery Disconnect Switch.
There Is A Way To Reverse Some Wiring To Be Able To Jump Start Off House Battery. But I Feel Having A Set Of Jumper Cables, Is A Good Addition To Clipper Tool Kit.
You Having Those High Output Batteries, Should Give You Many Years Of Service.

This Would Make A Great Topic For Maintenance On Clippers @ Future Rally.
Really Looking Foward To Seeing Your Upgrade.

Joe