I am in the process of purchasing the parts for my dual battery install next month. I have already installed the Shrockworks Dual battery kit.

My setup will be:
Odyssey PC34R-1500 68AH (34Ah usable for 50% SOC)
Redarc BCDC 1225D
Blue Sea 6 Fuse Block (Fridge, extra Blue Sea USB/12v in trunk and power to RTT Anderson plugs on cable - only connected when deployed) Charging ipad/phone. Maybe run a 12v fan or electric blanket.
160w Renorgy Flexible solar on top of RTT
Deployable 100w solar blanket to supplement above when at base camp.
Stich Pro-9100 (Running AUX lights/loads and controlling compressor)
Blue Sea 12v USB/cigarette outlet in trunk.


Reason for Renorgy on the tent is that we hike and climb so the rig is left at trailheads for hours. Did not want a 1000 dollar solar blanket left hanging while away. (Bonus is this is cheapish. Although, I think you can have overheating issues with is stuck to the tent.

Draw while camping
2AH x 12 = 24Ah for Fridge (Poss National Luna 55L)
0.9amps x 2 = 1.8 amps x 4hrs =7.2 amps for camp lights (Baja Designs S2 x 2)
Occasional 12v fan in tent 0.31A x 8hrs = 2.48Amps
TOTAL 33.68

Solar should supply 6-8 Amps for 6hrs (Weather Dependant) = 36 to 48amps
Also, topped up by Redarc when mobile each day.
Once static and present at camp will deploy a supplementary 100-120W blanket (Further 6-8amps)

We mostly travel around but may spend a day or two at one location. We never stay in the same place for much longer than 2-3 days.

Questions
1) Redarc states 6AWG wire for our cable lengths. (Would it be better to use 4AWG?) The Redarc will be mounted directly on top of AUX battery so seems overkill 4AWG. Also, states 40amp MIDI fuse for low resistance (Heat). (These things are huge) Would a 40amp circuit breaker or terminal mount fuse be ok? So, going with 8 AWG as recommended by Redarc. Ordered some metric 40 AMP inline MIDI fuse holders. Much smaller.

2) I want to run 2 pairs of cables to the rear for the fridge and Blue Sea 12v/USB. The fridge will be direct to battery via Anderson connector in rear. Is 10AWG good for the fridge or overkill? Hoping for lowest amp loss/most efficient. Going with 10 AWG for fridge with Anderson. 12 AWG for 12v USB/cigarette.

3) If I use 10AWG for the fridge will it be ok with a 50amp Anderson connector? I know Anderson is made for thicker gauge possibly 6AWG. You can purchase smaller terminal posts for Anderson so 10 AWG is fine.

4) Switch Pro will be mounted on the other side of the engine bay from the AUX battery. What size wire should I use? 2/4AWG? I know it's rated to 125A but would it ever draw that? Going from Blue Sea cable recommendation chart 2AWG would be required. Answered my own question 2 AWG it is.
5) I will be making a mounting bracket for the top of the AUX battery (Mount Redarc BCDC plus 6 fuse Blue Seas block) Will any plastic board be good for this? Looking at HDPE or Acrylic on Amazon 1/2 inch thickness. Never done this before so don't know the tolerances (strength/heat) of these materials. HDPE cutting board ¼ or ½ thick.

6) What gauge and how many wires can you fit down the windshield trunking?

7) Anyone have any ideas for a connection terminal for the solar (Plastic section at the base of the windshield corner) For connecting Anderson (solar). I may just run the cable into the hood then have Anderson connectors under there. Going with weatherproof SAE terminal in the plastic at the corner of the hood. Will utilise SAE to Anderson for solar. This will make adding more solar later easy.

8) Is it ok to earth the AUX battery to the chassis/frame? Or should I run it to the starter battery? What size cable should I use for the earth? Running earth from Redarc to AUX battery terminal, then going to run a length of maybe 2 AWG from AUX neg to Starter Neg. Couldn’t really find anything solid on gauge size. Normally use the same as the positive connecting the batteries. However, in this case, positive feed is via DC-DC so much smaller.


Trying to streamline the cable buying. I will use Marine grade Ancor cables.
10 AWG (To AUX RTT/solar and Fridge)
8 AWG (Redarc install)
2 AWG (Switch Pro)
12 AWG most over 12v loads (Roof lights/ AUX 12v/USB)

I already have a dual ARB compressor mounted to the starter battery. This will be controlled by Switch Pro but the power to remain on the starter. I only use it while the engine is running.
I will install a winch too powered from the starter.

All other accessories will be via Switch Pro (AUX).
6 Fuse Blue Sea (AUX).
Fridge direct to AUX.

1) With the charger mounted directly above the battery (so circuit length <5'?) redarc recommends 6AWG for 25A? That is overkill. Or are you asking about wire to the solar panel? I'd use the fuse they recommend, they're not that big and you can get in-line MIDI fuse holders.

2) I think 10 AWG is the most common I've seen used for the fridge, I ran 8 AWG because I had it. The pre-made ARB and Dometic wiring use 10 AWG for example.

6) I was not happy when I tried to fit 8 AWG wires in the windshield trim, I ended up going through the rear instead.

7) they make through panel connectors you can use, I have a place to plug in 120V for onboard charging but you could use a similar spot for solar. I have no idea what wire gauge this is so I'm not recommending this product specifically, but this is the type of socket I am talking about: https://www.amazon.com/dp/B0031BOTFC..._eiHiEbRQ7QJK2
and here is my suggestion for where you could install it (ignore the red circle i was showing the antenna mount). The plastic panel pops right off and you can drill through it, it's cheap to replace if you change your mind later:
https://i.imgur.com/B3K4UK6.jpg

Is that a NOCO? I have seen them for shore power. Guessing I could just use the connector you have with an Anderson on the other end.

yeah it's for a NOCO charger

i wouldn't use that same 120V connector for DC, but a similar with SAE or if you are using anderson, they have similar for anderson connections: Powerwerx PanelPole, Panel Mount Housing for Two Powerpole Connectors with a Weather Resistant Cover | Powerwerx

You appear to have planned a pretty solid set up. I'm planning something on these lines as well but am currently leaning towards the Manager 30 and a 75 Ah lithium battery along with a 100 watt solar panel. The Aux. battery will power lights, fridge and an inverter while the starter battery (Group 34 AGM) will power the air-compressor and winch..

@SnoRnR I would also recommend getting the 34-pc1500 vs the 34R if you are orienting the battery with the terminals facing inward like the oem battery, as the 34R would put the +terminal very close to the passenger fender wall. it it happened to move and touch there would be some fireworks.

I am actually just finishing up the wiring for my dual battery setup today using the shrockworks kit as well with a 34-pc1500

The manager 30 looks awesome. I wanted to keep the build as discreet and OEM looking as I could. I would have loved a bigger battery. I really think 100AH is a good size. Might put a Group 31 in the OEM location and swap the starter round in the future. Just weight seems a problem when you start going up to those sizes.

Here's a couple answers:

I use an anderson connector with my ARB wiring kit. The connector size you are looking for is an SB50 and they have connector for wires as small as 12AWG. Take a look at the datasheet and pick the appropriate connector for your wire guage: https://www.mouser.ca/datasheet/2/22...50-1652903.pdf

I would go with 2AWG if that is what is recommend for the length and amperage. Unless you predicted your build and know for sure you would never use 125A.

What you are talking about is HDPE, not HTPE. 1/2 inch is plenty strong, I did mine with 1/2 inch. I would use 3/8 if I was to do it again.
Here's my setup where you can see a picture of my bracket: Project - Dual battery setup

As stated above, you need a 34-PC1500. Refer to this diagram and take into account that the terminals are towards the firewall (updside down compared to the diagram from Odyssey): https://www.odysseybatteries.com/images/1500terms.gif

Awesome. Thank you. Yes, I meant HDPE. I will go with 2AWG. I know the Switch pro is fused at 125A but I doubt it ever draws that. I will only have lighting and basic 12v stuff connected to it. The biggest load will probably be a lighting bar or 2 x Baja SP6's on the front bumper when I get it.

SnoRnR In your post question #5,) try using 1/4" Acetal sheet -Delrin from Tapplastics.com. I used this for my dual battery set up. It withstands high heat and can be drilled and taped. always order more than you need just in case.

#2) I also installed a blue sea Below deck panel # 4353 in the PS rear fender well with a #5045 compact fuse block and a #2314 mini bus. fed by 2/#8 Ancor marine cable. this was fed via the PS rocker panels. a tight fit so I had to remove the outer insulation to feed it under the "B" pillar then install split loom. This is fed from a Bussman fuse panel next to my Aux. battery.
This little sub panel is for future use. It might provide you with enough power for your fridge and accessories.
I don't have a build page but if you go into my album I have pictures of my builds.

First off I would avoid putting your BCDC in the engine bay. I know that people do it but Redarc does not recommend doing it as it will be prone to overheating and be much less efficient. Put it out in front of the radiator with a Prado 150 mount if you can. Out of Town 4X4 in Australia has one as well as Redarc Australia. BCDC Mounting Bracket to suit Toyota LandCruiser Prado 150 | REDARC Electronics The mounting is exactly the same as on the Prado, but you have to move the horn mount a bit, it will be a much cleaner install. I would also use the Blue Sea Systems MRBF Surface and Terminal Mount Fuse Blocks. They mount right onto the battery terminal so that all cabling is protected, also easier to install and cleaner.
Heres my set up. You can see the Redarc 1240d just to the right of the hood latch.

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I'll second this (keep the BCDC out of the heat). I looked at the Prado mount, but it was going to be costly and slow to get this (all the way from Australia; at the time I was looking, there were none in-stock elsewhere, so mine would be a special delivery

My choice was to go with Off-Grid Engineering, and their Redarc BCDC Mount/ Battery Tray. This has a vertical mounting surface for the BCDC, and an orthogonal plate which is captured beneath the stock battery - simple!

I think this behind-headlight location is relatively cool, but then cooling is enhanced by the "prop-wash" of the mechanical engine-fan.

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@ruff4runner -- can you show how the Prado 150 mount attaches?

It mounts in front of the radiator on the left side right where the horns are, so you have to move the horns. The mount fits just as it does in the Prado 150. I cut out a hole in the radiator cover so I could see the LED readout.

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Thanks for posting and updating this! I recently did a dual-battery setup, and found your journey helpful. I'll add a bit (which I hope may help others).

I went cheaper (although I have used and like Odyssey), opting for a Costco Energizer AGM. Delivered to my door (thanks, COVID-delivery guys!).

Helpful, and it's great that you figured out your loads. When you plan and prepare like this, it's almost just simple accounting. I say "almost" because many devices are sensitive to depth-of-discharge and may stop working. And some folks will use battery boosters to maintain voltage to the device even as the battery terminal-voltage drops. My own rule-of-thumb is to only figure on 1/2 the listed battery-capacity, both for life, and reliability.

In my case, I enjoy ham-radio operation, and wanted my AUX battery to carry me through evenings and weekends of radio-operation. I also have future dreams of a winch.

For my Redarc hookups, I used 6AWG. I felt like it. It's more than what is necessary.

I did this. I actually chose to use TWO ground-cables, one attached to the inner-fenderwell up by the air-box and the other down lower behind the headlight (both were 6mmx1.0 bolts, where 5/16" ring-terminals work nicely). For my future dream winch, it will have it's NEG attached to the same bolt behind the headlight, and my ham-radio NEG will pick up from the bolt by the airbox. I changed both these bolts to stainless, and added nickel-anti-seize everywhere to guard against corrosion. I also neatly scraped paint off the horn so it's a reliable member of the conduction team.

Each Ground was made from 2/0 welding cable, with hydraulically-crimped ends, which were also soldered and heat-shrunk.

This was a weakness for me - I was slow and piece-meal. I kept asking myself, at each step: What is The Best? Then I would buy. I had no urgency, and this is more than half-hobby for me, so i enjoyed the journey.

Extras:
I am in Canada, and got the Comfort+ Complete package from Toyota. This includes an AC battery-maintainer which is pretty small. It would have made the Redarc turn on, draw too much, shutdown, turn-back-on, Redarc restart, shutdown, etc. So, I had to use a relay to only connect the Redarc to my Main Battery when the IGNition is RUNning.

Further, over the past decades, I've been in the boonies for a several days, and like the peace-of-mind of being able to jump-start my Main Battery. So I added a Cole-Hersee continuous-duty solenoid (200A cont, 600A intermittent) to let me "combine" the batteries in circumstances where I need to jump-start myself, or when I may wish to have the Main battery assist the Aux in prolonged winching.