Battery disconnect switch issue

[MNtraveler]

A funny thing happened when I installed a disconnect switch today. After adding it, I disconnected it (unscrewed the disconnect screw) and turned on the main battery switch to confirm all was off, and the vent fan went on (it was on when I turned the power off). Also the cab radio had come on. I think what is happening is that the wire connecting the two ground terminals is still connected to the coach ground wire even when the battery is disconnected, so it's running off the one battery. (See pictures of setup below.) So do I need TWO battery disconnect switches to completely shut off all power while in storage? Or should I attach the ground terminal connector wire to the battery side of the disconnect switch so it doesn't touch the coach ground wire?

PS: in case my footer doesn't show, it's a 2016 Forester 2401R MBS.





Land of 10,000 Lakes
2016 Forester MBS 2401R

[CHICKDOE]

please get a second opinion on this. but it looks to me as if the battery disconnect still allows current to flow from the other battery. look at the disconnect. on the side that gets disconnected there are two cables attached. one is the jumper to the second battery and the other goes to the loads. if you open the disconnect power could still flow from the second battery to the disconnected part of the disconnect where it joins with the cable to the loads. this is a complete circuit. I think you should move the jumper between the two negative battery terminals off the disconnect and place it directly on the battery terminal. that way only to load cable will be on the disconnect side. and when it is disconnected, both batteries will be disconnected from the load.

[Happy Vibe]

You don't need a second disconnect switch. You need to move the black wire from your second battery to the other side of the disconnect. You should only have one wire on the side away from the battery. If the post is not long enough you can buy an adapter to go on the round battery post to hook up to.

[dalford]

Originally Posted by Happy Vibe

You don't need a second disconnect switch. You need to move the black wire from your second battery to the other side of the disconnect. You should only have one wire on the side away from the battery. If the post is not long enough you can buy an adapter to go on the round battery post to hook up to.

X2, tried to edit my post but some how I deleted it... Good catch happy vibe..

[MNtraveler]

Thanks guys! Makes sense.


Land of 10,000 Lakes
2016 Forester MBS 2401R

[padcarroll]

Excuse my ignorance but why is the disconnect on the negative side? My class A disconnects are on the positive terminal.

[NMWildcat]

Originally Posted by padcarroll

Excuse my ignorance but why is the disconnect on the negative side? My class A disconnects are on the positive terminal.

Either way works. Most folks prefer the negative side due to simplicity I believe.

[dieselguy]

There are two schools of thought on battery disconnects ... each side is pretty passionate about the issue. Either way gets the job done ... I prefer disconnecting the negative.

[MNtraveler]

Originally Posted by padcarroll

Excuse my ignorance but why is the disconnect on the negative side? My class A disconnects are on the positive terminal.

Either side can be d/c'd, but it's generally safer to work on the ground side. Less sparking, and if you accidentally short something to ground it makes no difference. Whereas on the hot side you can weld your open end wrench to the frame.

[camaraderie]

Originally Posted by MNtraveler

Either side can be d/c'd, but it's generally safer to work on the ground side. Less sparking, and if you accidentally short something to ground it makes no difference. Whereas on the hot side you can weld your open end wrench to the frame.

Yes...additionally the + and - post terminals are different sizes and the disconnects for POSTS are made to fit the negative side...do NOT try to pound them on to a positive post!
There's also usully a bunch of positive wires vs a couple of negative ones...to it is easier to deal from the negative side as well.

[Vegasmailman]

You might want to think about the battery cut off switch with fuse bypass. That way if you don't lose any settings if any.

[NorSnrub]

I had a solar panel wires in directly and even when the battery was not there the fan would come on and led lights etc.

[Las Cruces]

There's no wrong answer to this. If you want to isolate the battery and be safe from accidental shorts when working around the battery put the switch on the “grounded” side. Either side being disconnected will prevent discharge without harming equipment.

[Tom48]

[QUOTE=Las Cruces;1282894]There's no wrong answer to this.


Unless you were plugged in 120 and your converter was running power to the house. Then all above, matters not. The place will run pretty much just off the Converter.

[awellis3]

Originally Posted by padcarroll

Excuse my ignorance but why is the disconnect on the negative side? My class A disconnects are on the positive terminal.

Actual current flow is he reason. Although the negative charged electrons move through the wire toward the positive (+) terminal of the source of electricity, the current is indicated on wiring diagrams as going from positive to negative. This is an unfortunate and confusing convention.
Ben Franklin originally named charges positive (+) and negative (−) when he was studying static electricity. Later, when scientists were experimenting with electrical currents, they said that electricity travels from (+) to (−), and that became the convention.
This was before electrons were discovered. In reality, the negative charged electrons move toward the positive, which is the opposite direction that people show current moving. It is confusing, but once a convention is made, it is difficult to correct it. Therefore, disconnecting the negative terminal stops all electron flow making short circuits impossible.