Battery disconnect

[mcarter]

What battery disconnect is recommended , how connected and on positive or negative side? THANKS


RP 178

[CHICKDOE]

on negative side! as far as a recommendation that depends on what you want. the simplest seems to be knife switches that mount right on the battery terminal. they have another post that you relocate the cables to. simple open / close knife switch. 10 minutes max to install. but can you use this? will it fit? my batteries are in a battery box so this won't work for me. i'm running a new cable from the battery to a switch that I will mount on the wall. a little more work but it will do. the most exotic are electric switches operated by a remote key fob type device. nice but probably more work and more $'s.

[mcarter]

Thank You, I thought negative also. Mine is also in a box, and I like the wall idea. Much appreciated.

[TURBS]

Positive or negative is mine is on the positive.




2015 Columbus 320RS
2008 2500HD Duramax
2015 nights camped "34"
2016 nights camped "22"

[HalfBubbleOff]

Can someone explain why negative disconnect is better than positive?

[clr]

Weither you are talking about electron flow neg to pos or hole flow pos to neg the direction the current is flowing is somewhat unimportant. In an RV the negative post of the battery is connected to ground. You should place the battery disconnect on the positive side so that no accidental short to ground any were in the RV would cause arcing and or operation of the device. In AC per the code the switch always goes on the hot side of the circuit and not on the return side. The same logic should be followed on DC circuits. So will a disconnect work on the negative side yes it will. But if you turn off the disconnect and work on the unit thinking that the battery is disconnected you will be in for a surprise if you accidentally ground the unit you are working on. It is best to not have the power in the lines looking for a ground so IMO it is best to always place the disconnect on the positive terminal.

[Happy Vibe]

I disagree with clr . Looking at DC using a battery is complete different than 120AC. If you disconnect either the positive or negative you no longer have a complete circuit. If you disconnect the negative and then touch a positive to the frame nothing will happen because you do not have a complete circuit, negative is disconnected from the frame. AC is completely different. With 120V you can have a complete circuit through a ground point the earth. Or other objects in a house most water systems are used as a ground ( I know new homes use pex so this my no be true) so if you touch a sink and hot wire you complete the circuit. There is also enough voltage that you can get the few milliamps needed to electrocute you. If you had a 120V DC I would say disconnect the positive.

[Asrabbit]

I asked this same question, and got a number of answers. Here is a thread you can read:

http://www.forestriverforums.com/for...ch-104704.html[/URL]

[mcarter]

Interesting discussion, I am somewhat familiar with electronics. I think I had a simpler reason for tying my disconnect to the negative side. I was adding cabling and a switch to the battery. When I thought about camping and road debris, I considered if something damaged or shorted a cable , I would want it to happen to the negative side vice the positive side. Maybe flawed logic but I feel safer. If an errant piece of rebar from the hi-way pokes thru my switch it's not going to short the positive side of the battery to the frame. Granted your cabling is at risk, but I am pessimistic enough to not want to enable failure. Just my 2 cents.

[johnbryanpeters]

I'm an electrical engineer with an extensive background in power systems. The canonical location for a DC disconnect is in the positive lead.

I'm planning to rebuild my whole battery system with

• Secure mechanical hold-down rather than relying on gravity and cheesy plastic straps.
• A disconnect switch.
• A 100 A shunt in the ground lead to support a Trimetric TM-2030-RV battery system monitor.
• Positive and negative bus bars for power distribution to trailer.

I'm considering having a lockable battery box fabricated from 18-8 stainless with provision for mounting disconnect, shunt, and bus bars. If I get my act together and do it, I'll post photos.

[this_is_nascar]

Sounds like overkill, but have at it.

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