Suggestions please on 4Runner rear power

[taco007]

Hi: Can you experts here check my plans please? I have a 17 4Runner and am planning on running a National Luna Fridge. I'm planning the following, in hopes of future add ons:

4 Ga, with Bussman 60 amp circuit breaker near battery, wire run along door plates and into fender area in rear cargo (driver's side). I would like to terminate to a Blue Sea 6 place fuse block, and then run my fridge off that. My concern/question is any issues attaching the heavy Ga wire to the fuse block? Can I step it down to a smaller wire to attach to the fuse block (I don't think they make 4 Ga. to the small screw/post on the Blue Sea box. I would run a negative/ground to the body panel of the truck.

Also, If I do this, can I get away with only running one 4 g wire (positive), or do I need both pos and negative? (Silly question but I'm new to this flowing electron stuff)

Thanks in advance

 

[Wallygator]

Is 4awg necessary to the rear?

 

[DaveInDenver]

You can terminate 4 AWG to a Blue Sea fuse block, which have #10 stud for the positive and negative bus connections. Part number Molex 19193-0254 is just such a terminal. Whether that's necessary or not, not sure. I ran 8 AWG to the rear fuse block for a fridge and for that it's more than fine. But would some day like to rerun with 4 AWG to minimize voltage drop since I'd like to hard wire a compressor.

https://www.mouser.com/ProductDetail/538-19193-0254

 

[Wallygator]

You can terminate 4 AWG to a Blue Sea fuse block, which have #10 stud for the positive and negative bus connections. Part number Molex 19193-0254 is just such a terminal. Whether that's necessary or not, not sure. I ran 8 AWG to the rear fuse block for a fridge and for that it's more than fine. But would some day like to rerun with 4 AWG to minimize voltage drop since I'd like to hard wire a compressor.

https://www.mouser.com/ProductDetail/538-19193-0254

View attachment 499900

Nice. I purchased 6 awg and was worried it may have not been sufficient. Thanks.

 

[DaveInDenver]

Nice. I purchased 6 awg and was worried it may have not been sufficient. Thanks.

Whether 4, 6, 8 or 10 depends. Even a 10 AWG is pretty decent for lights and a fridge. Larger load, maybe more sensitive to voltage drop, charging a battery back there, it might not be ideal. There's no practical downside to larger wire other than cost and ease of handling. But it's not necessary to over spend if you don't need it either.

 

[dreadlocks]

Fridges w/Low Voltage Disconnects (LVD) can be fickle since they are sensing voltage so far away from the battery, when battery gets low it can cause em to shut down prematurely.. gave me grief w/my ARB fridge, I dunno if NL has an internal LVD but many have hard set values so after a bit of a wiring run instead of disconnecting when battery is at 40% it might disconnect at 60-70% because a few tenths of a volt drop under load is all it takes.

Installing a heavier gauge wire than needed, especially if the fridge is not alone on that circuit is usually worth it, to an extent anyhow.. too big and its going to be a pita to route through the cabin.. If fridge dont have an LVD you can install an external one but put it much closer to the battery and it'll work better than an internal one w/out oversizing wiring.

 

[taco007]

Thanks everyone for the replies. To answer the question asking if 4 ga, necessary, I doubt it but wanted to go oversize rather than under. I had 10 ga previously and had issues. The issues previously could have been the various connections though. I'm a rookie at wiring but am getting better. The NL does have a LVD.

Because of these previous issues, I am trying to get it right on my new rig. I am going to eliminate as many connections as possible. No more Hella plug for the NL fridge. I have found that it wiggles/wears.

4 Ga. is a PITA to run through the cabin, as stated above. Running one wire (positive) is something I am considering, having the negative route to ground through the blue sea fuse panel, but understand it's not ideal.

As for fusing the run of 4ga, is the 60 amp breaker sufficient for the wire run, considering it's being run to a fuse box? Do I need a 15 amp fuse near the battery as well (owners manual calls for it)?

 

[dreadlocks]

These are what I use for fusing a new large circuit right off the battery: https://www.amazon.com/gp/product/B0019ZBTV4/

this is a decent help: http://circuitwizard.bluesea.com/

you should have a fuse near the battery that will blow before your wiring takes damage.

 

[SouthAfrican77]

I think you need to try define the future loads you plan to add to define the load, use a fudge factor on top and then land on a max current window you expect to see, then backtrack the acceptable voltage drop from there to land on the heaviest gauge needed, so as not to go over the top with dealing with a 4GA if not really required.
For instance at about 10ft of cable run on a 12V system you need a load of 16amps to drop the voltage by 0.2V on a 10ga wire. That is a pretty big load (Luna fridges run ~2A for sake of simplicity) and I suspect previous issues you mention may have been located at connections rather than the gauge itself. Working with 4ga wire is a PITA - I suggest using the right wire and minimize connections. Outbackjoe wrote a very good summary on overland power systems and his section on voltage drop and cable size should help you answer some questions. Good luck with the install! https://outbackjoe.com/macho-divert...ms-dual-batteries-solar-panels-and-inverters/

 

[JPaul]

If you think 4 gauge is a pain, try routing 3/0 in the dead of winter.

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