Batteries connected correctly?

[fickerdm]

I tried to hook up a battery disconnect switch today but it would not disconnect power. I tried on both the black cable and red cable on the right battery in the pic. Looking at my dual 12 volt batteries it appears my batteries may not be hooked up correctly. This is how they came installed from the dealer. We have roof mounted solar and those are hooked up to the left battery only. It appears my batteries aren’t in parallel like they should be. It’s my understanding that the black cable on the left battery should be going to the RV for parallel. On mine the black cable on the right battery is going to the RV.

[Flybob]

They look correct to me if I am understanding the two cables on the right go to the RV. I see pos of left battery connected to pos of right battery then to RV. Neg on Left battery connected to Neg on right Battery then to RV assuming frame. Looks like solar is connected to the left battery, but the batteries are connected together properly.
Looks like shutoff needs to go between the red cable on right and the Pos terminal on Right battery. The cut off may not work on the neg cable on the right battery as there may be a solar connection to the frame somewhere that is then connected to the left battery neg terminal.

[TheGerman]

Agree, wiring looks correct. Did you disconnect shore power when testing the disconnect switch ? If not the converter will still power the 12V lights etc....

[cavie]

You disconnect needs to be connected to the right battery. It needs to disconnect the RED cable on there right battery going to the trailer. It will not disconnect the color as it is only hooked to the left battery.

[fickerdm]

Originally Posted by TheGerman

Agree, wiring looks correct. Did you disconnect shore power when testing the disconnect switch ? If not the converter will still power the 12V lights etc....

We weren’t on shore power.

[fickerdm]

Originally Posted by cavie

You disconnect needs to be connected to the right battery. It needs to disconnect the RED cable on there right battery going to the trailer. It will not disconnect the color as it is only hooked to the left battery.

I put the disconnect on that red cable on the right battery. Still had power

[pgandw]

In your photo, every terminal has more than one connection. Any battery post cutoff switch cannot cut off wires going from the trailer to the same polarity on the other battery.

Ideal parallel wiring:

ALL trailer red wires would go to the left battery positive post - through the cutoff switch. There would also be a single cable going from the left battery positive post (bypassing the cutoff switch) to the right battery positive post - and that would be the only wire going to the right battery positive post.

All trailer black wires would connect to the right battery negative post. There would be a single black wire going from the right battery negative post to the left battery negative post.

The method I listed above is not my favorite. If you are paralleling 12V batteries, I prefer the 4 position marine battery switches ($30 on Amazon) so that you can parallel/unparallel the batteries with the switch, as well cutoff all loads. These switches will have instructions that show all positive load wires coming to one post of the switch, another red wire to + post of battery 1, and another red wire to + post of battery 2.

just my experiences
Fred W
2019 Flagstaff T21TBHW A-frame with dual battery cutoff switch
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[TheGerman]

Do a simple test: Remove both red cables from the right battery. If you still have power in the trailer there's some backfeed through one of the smaller wires on the left battery.

[Herk7769]

It's pretty obvious the cables are not hooked up in a way that is optimum for a dual 12 volt battery setup (even disregarding the smaller wires that are hot connected to the left battery).

A dual 12volt battery system needs to have the feed/load positive to one battery and the ground/frame wire on the other battery.

With so many feed wires, it might be easiest to consolidate all the ground wires and the wire that goes to the trailer's Converter to the "dead"/Frame side of the disconnect switch.

[Chuck_S]

The diagram above is correct. Put a marine switch on the Negative wire before it gets grounded to the trailer frame any you're all set.

The 12vDC from the converter Negative wire should go to the trailer frame as well.

-- Chuck

[ejohnson1144]

I think your negative to the camper needs to go to the left battery

[fickerdm]

Update. So I figured it out today. In the attached picture there are 3 smaller gauge wires on the positive posts on the left battery One is the power tongue jack. One of the smaller red is from the solar charge controller. The other red wire is where I needed to put the switch. Not sure where that wire goes. The second picture shows the rewired batteries. I connected them in proper parallel and moved all positive wires to the left battery and all the negative wires to the right battery.

[ejohnson1144]

Looks like you have only 1 wire going to the disconnect switch ?

[fickerdm]

Originally Posted by ejohnson1144

Looks like you have only 1 wire going to the disconnect switch ?

There’s a second wire. Just can’t see it in the pic.

[Herk7769]

Where does the big red wire on the right battery that goes under the box go to?

[ejohnson1144]

Red wire that feeds rv should be on the switch and the Battery feed should be on the switch
Otherwise disconnect won't turn off power to your rig.
There are 2 terminals. In and outgoing.

[Chuck_S]

It's really this simple.

Connect your batteries like below (previously posted I'm sure).

Note the batteries are connected together (parallel) and the positive and negative wires run to different batteries. As far as the battery gods are concerned this is one big battery, not two. Ignore the other terminals.

Connect ALL the Positive wires to to the top battery and the single Negative wire (there should only be one) to the bottom battery. Connect that Negative wire to the disconnect switch and from the switch to the frame (ground). Switch the ground. One wire into the switch. One wire out of the switch and then to the trailer frame.

The top battery in the diagram is where all (meaning every one of them) the Positive wires connect. Nothing but the jumper connects to the bottom battery Positive connection; likewise nothing but the jumper connects to the top battery Negative connection.

Turning the disconnect switch Off -- wait for it -- disconnects all the batteries from the system.



-- Chuck

[fickerdm]

Originally Posted by Chuck_S

It's really this simple.

Connect your batteries like below (previously posted I'm sure).

Note the batteries are connected together (parallel) and the positive and negative wires run to different batteries. As far as the battery gods are concerned this is one big battery, not two. Ignore the other terminals.

Connect ALL the Positive wires to to the top battery and the single Negative wire (there should only be one) to the bottom battery. Connect that Negative wire to the disconnect switch and from the switch to the frame (ground). Switch the ground. One wire into the switch. One wire out of the switch and then to the trailer frame.

The top battery in the diagram is where all (meaning every one of them) the Positive wires connect. Nothing but the jumper connects to the bottom battery Positive connection; likewise nothing but the jumper connects to the top battery Negative connection.

Turning the disconnect switch Off -- wait for it -- disconnects all the batteries from the system.



-- Chuck

That’s what I did but the disconnect would not work on the wire going to the trailer frame. I had to put the disconnect on another wire which I think goes to the inverter. As in the attached figure.

[ejohnson1144]

That is correct

[TheGerman]

Sorry, that rat's nest does not look right. It's switching something but the positive and negative from the camper still connect directly to the batteries. Also, the way the switch is mounted the threaded ends are going to rub against the battery housing when driving, possibly damaging it.