offroad lighting wiring sanity check

Thanks to all the great posts here I've learned a lot about wiring a 12v system and think I'm at the end of my planning phase. Before I burn my rig to the ground, I'm looking for some advice and a sanity check on my game plan. I'm using usmcdoc14's writeup on JKOwners.Com as my wiring bible so assume I will be following the proper gauge, connection methods, etc.

The Sanity Check

This is going on my 99 Jeep Cherokee. My plan is to add a dual battery setup using the Blue Sea ACR setup to allow for battery isolation and combination with an in-cabin control. I'm connecting everything via 2 gauge welding cable. I'm going to run a custom switch panel with a relay/fuse assembly under the hood (or multiple boxes inside and outside of the cabin to minimize cable runs if that makes more sense).



So my questions for the overall plan are:

• Does this look like a good plan?
  
• What am I missing?
  
• Have I future proofed the install enough?

The Knowledge Gaps

Most of the switches are straight forward SPST turning the accessory on/off. The couple of exceptions which I'm looking for input are:

• Winch - I want this to energize the winch and bridge a jumper on the fuse box which activates the XJ's high idle (raises the idle to 1000-1200 RPM)
  
• Rear lights - This is a SPDT which I want to either turn them on with the ignition off, have them come on with the reverse lights, or be disabled completely
  
• Stereo headunit - on automatically with the ignition or bypass the ignition and just turn on
  

Any other comments or advice welcomed. I thought I knew a lot about wiring until I started doing research on this so I'm looking to learn.

Forgot the info on my rig: 1999 Jeep Cherokee (XJ)

Simply run the power wire you use to supply power to the winch (when switched), to the high-idle as specified in the link you posted. Use a diode in the power wire to the high idle you added, so when high idle is on because it's needed, the winch isn't also powered.

Can run a battery power from a switch to the reverse light, easy, just put a diode in so the rear lights don't supply power to the reverse lights when you go into reverse.

Radio? Well, your radio has a momentary push power button, so, unless it is a mechanical switch that you can leave ON, you can't have it come on with ignition. If you want to turn it on without a key, you need to wire the IGN power lead at the radio, to a Battery + lead.   If you still want the ignition power to stay stock, then you need to splice a diodes into the IGN lead and B+ to the radio, so your IGN isn't always powered by the B+ wire you spliced in, and the IGN won't go back to the battery.

On the diode (o-->|--o), the stripe indicates flow of current, so the stripe will face toward the device/splice point you are sending power to, so power doesn't flow BACK through the diode when power is there from another source.

(B+)------o-->|------o\
(IGN SW)--o-->|---o/----RADIO

WINCH SWITCH------o-->|--o(WINCH)
(A12)---o--|<--o----------------/

You can figure out the lighting deal...

IMO that Blue Sea is very expensive as a battery isolator (ie, $260).

Do you have a charge light - ie, an alternator with a D+ or L terminal?
If so, have you considered a relay controlled by that circuit - ie, when D+ or L goes to +12V (ie, the alternator is charging) it turns on a relay that interconnects the 2 (or more aux) batteries.
If it's a big relay to switch (say) 100A or more, a smaller "buffer" relay or circuit (transistor or MOSFET etc) may be needed between D+/L and the isolating relay(s).

I (and others) have referred to such an isolator as the UIBI (google UIBI or "oldspark uibi").
It avoids many complications of voltage sensing aka "smart" battery isolators (different voltage thresholds; essential switching delays; standby current); is easy to augment (manual connection or override) and should cost the same as the voltage-sensing isolator's relay but without the cost of its control circuitry.   


And FYI - I use automotive fuse & relay boxes (these days with micro-blade fuses and micro relays etc) since IMO they are more robust than aftermarkets which seem brittle else prone to fatigue and/else expensive.