What gauge wire to run between house batteries

[JeffAndPam]

Here are my existing house batteries, which have a monster wire running between them:

I'd like to install the following two components between these two batteries: A disconnect switch, and a meter:
(This would go in the space in the lower right)

The current wire running between these is pretty thick.
Would I be ok running two 2 awg, or 4 arg wires between them?
Something like: https://www.amazon.com/ABIGAIL-Battery-Inverter-Automotive-Motorcycle/dp/B0BV9TYY5D/?tag=rvf01-20

 

[Texas Clodhopper]

This would be a good start.

What Battery Cable Size Should I Use?

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[Jim]

Here are my existing house batteries, which have a monster wire running between them:

View attachment 22481

I'd like to install the following two components between these two batteries: A disconnect switch, and a meter:
(This would go in the space in the lower right)

View attachment 22483 View attachment 22484

The current wire running between these is pretty thick.
Would I be ok running two 2 awg, or 4 arg wires between them?
Something like: Amazon.com

May I ask why?

The "giant" wire is what connects the two 6 volt batteries (series) and allows them to provide 12 volts. Is the disconnect switch being installed to intentionally terminate this connection for a reason, or are you trying to achieve something else?

Just trying to understand goal here.

 

[TheLooks]

Disconnect switch should be on negative cable to ground of both batteries not between them. Shunt can be on positive cable.

 

[Chuggs]

With only two batteries 100% of the current goes thru that connecting wire. The wire should be rated for the ampacity of the catastrophic fuse used on your coach. What it the fuse ampacity?

Placing a shunt between the two batteries isn't a common practice.

The shunt is normally installed on the NEGATIVE lead from the battery...it rest between the battery and all of your loads... this way it sees everything going in and coming out. Many of them use the ground as part of the voktage sensing. Having it stuck between two series batteries would mess that up.

 

[JeffAndPam]

Looks like I got some valuable feedback from everyone. Thank you.
BTW @Jim I have two separate goals (but could be related): Install a switch, install a meter.

First, I decided to go with 2 awg to play it safe (I've seen some go as small as 6-8 awg, but I'd rather not).
As for the meter, I'll work that in separate from the switch.

As for placement of the switch, I'll forgo placing it between the batteries.
It seems that most suggest attaching to the negative terminal, however I do see some placement on the positive terminal. That would be more convenient to in my case, due to where I'd like to place the switch (lower right corner of that picture).

Being one who likes to learn:
What are the reasons placement on the negative terminal is preferred?
Or...what should be my concerns for placing it on the positive terminal?

 

[Chuggs]

Looks like I got some valuable feedback from everyone. Thank you.
BTW @Jim I have two separate goals (but could be related): Install a switch, install a meter.

First, I decided to go with 2 awg to play it safe (I've seen some go as small as 6-8 awg, but I'd rather not).
As for the meter, I'll work that in separate from the switch.

As for placement of the switch, I'll forgo placing it between the batteries.
It seems that most suggest attaching to the negative terminal, however I do see some placement on the positive terminal. That would be more convenient to in my case, due to where I'd like to place the switch (lower right corner of that picture).

Being one who likes to learn:
What are the reasons placement on the negative terminal is preferred?
Or...what should be my concerns for placing it on the positive terminal?

Valid question. Not sure there is a correct answer. It may be as simple as why do they color Pos and Neg with RED&BLACK or BLACK&WHITE?

Standards go a long way toward reducing the time it takes a technician to correctly identify the wiring architecture and do work without wasting a lot of time. If you are paying someone $125 - $200 per hour...I think it is in your best Interest to not go rogue and buck convention. It would only delay your results and add cost.

Make the technician nod their head up and down vs side to side when they survey your wiring.

 

[Kevin D Pem]

The reason the shunt Is on the negative is that the circuitry in the meter/battery manager is easier to engineer that way. The reason the battery disconnect should be on the ground side is it is much more likely you will short the battery out to ground than to something on the positive side of things.

 

[Kevin D Pem]

When it comes to the wire size between the 2 6v batteries, larger the better! The required size should match the largest discharge you are likely to have. The larger the better is based on least resistance, making the balancing act less of an issue. All above information is very sound, so follow what you will, it's all good!!!

 

[JeffAndPam]

The reason the battery disconnect should be on the ground side is it is much more likely you will short the battery out to ground than to something on the positive side of things.

Indeed. Just after posting that I pondered the notion of accidentally touching metal (thereby ground). So yes, negative side makes sense. Tnx.