How to: Battery Disconnect
A common problem for RV'ers (not just TT owners) is a low or a dead battery. The reason for this is parasitic power drain. A single light left on can obviously drain the battery quickly but there ar...
Forum Discussion
Jerem0621, thanks for the writeup sometimes we take what is perceived as the simple things for granted and assume "everybody knows" I think it's great that you took the time to post this for everybody. But I agree with many of the posters who have concerns about the breakaway switch. Below are my suggestions and reasons why it might be better to move the switch to the positive terminal.
As far as your emergency breakaway switch, I would think you could just take the negative wire from the switch, put on a ring terminal, and attach it to the threaded negative post on the battery. At least I believe mine has a separate negative wire. BUT, if your breakaway is grounded through the mounting bolts to the frame this won't be an option. At that point the positive terminal is your only real option as stated in the next paragraph.
If your emergency breakaway has only one wire, the only thing you can effectively do is to move the disconnect to the positive terminal on the battery. Then using a separate ring terminal connect the positive on the breakaway to the threaded battery post. This way you can disconnect the loads on the battery and the breakaway will work fine whether or not you install the green knob.
As far as which side to put the disconnect on in reality I don't think it matters as long as you can keep the emergency breakaway available regardless of the disconnect position. I know of two different reasons I've heard for disconnecting the negative side of a battery and they both make sense. But they probably don't really apply in this application.
Reason 1. When disconnecting the battery on your tow vehicle you always disconnect negative first and reconnect it last. This is a safety issue as if you happen to slip with your wrench and connect a circuit between the negative terminal and the vehicle body nothing bad happens. But if you try to disconnect the positive first and slip with the wrench to the body you will get a direct short causing lots of sparks and heat and possibly welding the wrench to the body which would be really dangerous.
This is not the case on the green knob as there is nothing long enough to cause a short to, regardless of the terminal you attach it to.
Reason 2. I once worked as a technician for a major automobile manufacturer. During one of the many training classes I had to attend, I was told that in the computer circuits that they always switch on the negative side of the circuit. This is because the current has already been used and therefore there is less arcing and therefore less wear on the circuits.
I can see this as a concern on a microprocessor where there is very little material on a conductor that can erode before it stops working. In the case of the disconnect switch you have a large conductor and almost no sparking. And if by chance you manage to erode away the switch through sparking, a new switch is cheap and easy to install.
All that being said, if I did buy and wire a disconnect I would wire it on the positive cable with a separate wire for the breakaway.
As far as your emergency breakaway switch, I would think you could just take the negative wire from the switch, put on a ring terminal, and attach it to the threaded negative post on the battery. At least I believe mine has a separate negative wire. BUT, if your breakaway is grounded through the mounting bolts to the frame this won't be an option. At that point the positive terminal is your only real option as stated in the next paragraph.
If your emergency breakaway has only one wire, the only thing you can effectively do is to move the disconnect to the positive terminal on the battery. Then using a separate ring terminal connect the positive on the breakaway to the threaded battery post. This way you can disconnect the loads on the battery and the breakaway will work fine whether or not you install the green knob.
As far as which side to put the disconnect on in reality I don't think it matters as long as you can keep the emergency breakaway available regardless of the disconnect position. I know of two different reasons I've heard for disconnecting the negative side of a battery and they both make sense. But they probably don't really apply in this application.
Reason 1. When disconnecting the battery on your tow vehicle you always disconnect negative first and reconnect it last. This is a safety issue as if you happen to slip with your wrench and connect a circuit between the negative terminal and the vehicle body nothing bad happens. But if you try to disconnect the positive first and slip with the wrench to the body you will get a direct short causing lots of sparks and heat and possibly welding the wrench to the body which would be really dangerous.
This is not the case on the green knob as there is nothing long enough to cause a short to, regardless of the terminal you attach it to.
Reason 2. I once worked as a technician for a major automobile manufacturer. During one of the many training classes I had to attend, I was told that in the computer circuits that they always switch on the negative side of the circuit. This is because the current has already been used and therefore there is less arcing and therefore less wear on the circuits.
I can see this as a concern on a microprocessor where there is very little material on a conductor that can erode before it stops working. In the case of the disconnect switch you have a large conductor and almost no sparking. And if by chance you manage to erode away the switch through sparking, a new switch is cheap and easy to install.
All that being said, if I did buy and wire a disconnect I would wire it on the positive cable with a separate wire for the breakaway.
