Getting myself into the weeds - help me simplify wiring

[Chorky]

Ok so I have a series of planned events that I previously had a wiring diagram drawn out for but since have realized it was probably overly complicated...

The overall plan was for the below items to be functional off a second set of batteries the same as the vehicle batteries ('97 OBS 7.3) for redundancy. The house batteries for the living situation would be different of course. This is for redundancy, and to avoid using house batteries for said components, but to allow the below components to be ran while the engine is off. Some of the lights could be wired to the factory batteries, as, well, those likely should not really be on with the engine off - except for rock, engine, dome lights.

So the overall question, is how would you wire these? My current thought is, for items inside the cab, to have a single power wire linked to a distribution block, and these items run to the block independently. For the items outside the cab, to also run to a single distribution block / relays, to avoid a billion hook-ups to the batteries.

Under hood lights - 2x.04 = .08a
1) Fog lights - 2x1.6=3.2a
2) Side flood - 2x1.6=3.2a
3) Flood - 2x5.5=11a
4) Spot - 2x5.5=11a
5) Rear - 4x2.9=11.6a
6) Rock - 8x0.4=3.2a
7) Dome - 4x0.4=1.6a
8) CB - 5a
9) GMRS - 15a
10) HAM - unknown
11) Cell extender - 5a
12) Compressor - 44a
13) Wabesto Thermo C - 3.8a
14) Inverter (for computer/drone charging) - unknown

Now to complicate things:
Again the thought is to have items 6-13 to be able to be ran when the engine is off (likely not really going to happen often, except for the diesel heater) without draining batteries to the point the truck wont start, which of course, remember it's a 7.3. So the thought is to have a second set of AGM batteries in the bed. These would be separate from the planned house lithium batteries for the camper. So, this leads me to believe I would require two (2) DC-DC chargers? Am I expecting too much from this system? I do have a 200a alternator, not installed, available...

 

[NatersXJ6]

How often are you really going to fire up 3 radios on full power transmit, lights, and a compressor at full load simultaneously?

The reality is that most of those things are listening or in standby 95+% of the time and drawing almost nothing. I would just put in the largest batteries the trays can hold and not look back.

 

[Chorky]

Not likely. But the radios and compressor could be on with key off quite frequently. Glow plugs draw a lot of amps. So I dont want to cause any other additional key off drain on the main batteries.

 

[VanWaLife]

My advice: be careful that you don't create a system that is so unwieldly / problematic that it cancels out the benefit of redundancy. In setting up my dual battery system, I've been unpleasantly surprised by the number of devices required to really get it working right, and adding a third isolated battery system will require even more gear.

But I do understand the need for these three systems. As far as wiring goes, I'd put a resettable circuit breaker very close to the battery, run a large wires from that to fuse blocks in the cab, engine bay, etc., then wire your devices to the fuse blocks. Try to color code wires and maybe tag devices and fuse blocks to help you remember which device is running of which system. You will probably want a low voltage cut-off on the new battery systems.

Looks like these guys have a pretty trick set up for three isolated batteries. It's a lot of gear, lots of new stuff to break.

 

[Superduty]

So you will have 6 total batteries in this truck? That seems like overkill. Can you run #13 from the house lithium batteries? Then just make sure you charge those batteries daily.

 

[Chorky]

be careful that you don't create a system that is so unwieldly / problematic that it cancels out the benefit of redundancy.

Its why I'm trying to go simple, and figure out the best method for the least amount of wiring while maintaining safety and a high level of functionality. I think having all the in cab components (7-11) ran off of a distribution block in the cab would be nice as it would reduce multiple wires needing to run through the firewall - would only need a +/-, maybe 6 ga. Additionally, the power for the exterior components (1-6 and 12-14) could come from the inside dist. box and have the negative (power switched) ran outside to a relay box which would activate the higher amperage circuit to power that device.

So you will have 6 total batteries in this truck? That seems like overkill. Can you run #13 from the house lithium batteries? Then just make sure you charge those batteries daily.

Overkill, sure... In a perfect world yeah. In all reality, not likely going to happen this way... But I think more reasonable is the factory 2 start batteries, 1 AGM in the back primarily for items 6-13, and one lithium house battery. And more likely will be just 2 AGM batteries and making due with those for a simpler house system. But the reason behind this idea is it may take a while to get that house battery set-up for the camper. Ideally, it could be done all at once - but on a poor man's budget here. To simplify, all these items could be ran on the main vehicle batteries of course, and just run a charger when #13 is on and near a power source. But the idea is to have capability to run items with engine off since we all know how noisy those 7.3's are, especially for items 7, 11, and 12. And to start the truck, just to run the compressor for 15 minutes is not a good idea for engine wear, in cold weather.

To further complicate matters - again, is having read up on another persons post here, I am now hesitant to consider lithium until I research more DC-DC charge ideas as another poster found a problem with red arc managers not charging below 40 deg. I believe it was. Where I am, it has not been above 40 for the last week. Typical winter temps are an average of low teens during the day, and -teens at night - this system needs to be functional in dead of winter for me. So more realistically is likely sticking with AGM I would believe and a simple old school solenoid style charger system - however, that has big drawbacks of causing unequal charge among batteries, and overcharging the main vehicle batteries, not to mention the relative useless amp hour amount of AGM's and the near inability to even find those ratings. Unless someone here knows more than me and has a suggestion?? Only other option I can think of is heating pads for batteries to keep them up above 40 deg at least - but that creates a large constant drain.

 

[Buddha.]

I’ve never used one but I think there’s some kind of Ford bracket used on the vans to mount batteries down on the frame. You could get a couple golf cart batteries for your auxiliary’s (if they fit the brackets), golf cart batteries are better bang for your buck than normal agm’s. Mounted outside the box there would be no off gassing concerns. You would then just run a fuse panel off of your aux batteries, and connect them to the starting batteries with an isolator.

Since the GC batteries are 6v you have to use them in pairs to get 12v. Do not buy 8v GC batteries.

 

[Chorky]

quick down and dirty schematic, that I need to polish up for sure as it's not fully accurate, but gives an idea. Constructive criticism welcome.