welove2drive
Southwestern Illinois
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As with any connection of this kind it is always better to use the -, or ground side. This prevents the possability of a short if any of the cables touch anything grounded.
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Yahooligan
Temecula, CA
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Something else to consider, you always want to connect the -/negative side last, and in this case put the disconnect on the -/negative side, to prevent a power spike to your electronics when/if there is an arc. Doing +/positive side last will generate a power spike as the voltage jumps across the arc, this can travel downstream and damage electronics. Doing -/neg last prevents this.
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2005 Nissan Titan CC SE 4x4
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Art D
Louisiana
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4*phun*2 wrote:Why?
For safety, before you do anything at all on the positive side of a battery you always want to disconnect the negative side.
Geaux LSU
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mobilefleet
ga
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I'm a mechanic and I'd put it on the negative side for sure
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Fabguy
Auburn, Washigton
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I've installed several battery disconnect switches on many vehicles over the years... Including boats, farm tractors and travel trailers. I always put the switch on the positive side with no ill effects.
Having said that... If I'm going to disconnect a battery on a vehicle without a disconnect switch installed I always disconnect the negative cable first.
Jeff
2002 GMC Sierra 2500HD 8.1/Allison/4:10/Prodigy brake controler/Dual Cam HP
Pulling a 2004 Sprinter 274 RLS
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flguppie
Stuart
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Ok, so I'm a little confused. I just finished this weekend putting a battery disconnect switch that I bought at the local marine supply store on my TT. The switch is made by Blue Sea Systems.. The directionscall for it to be connected to the + side.
What's up with the two stories here?
FL-Guppie "small fish in a big pond"
2010 Trail-Lite TLX200rk Crossover Tail-Gator
1997 Dodge RAM 1500 5.9L
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GuyM
The Great Midwest
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flguppie wrote:Ok, so I'm a little confused. I just finished this weekend putting a battery disconnect switch that I bought at the local marine supply store on my TT. The switch is made by Blue Sea Systems.. The directionscall for it to be connected to the + side.
What's up with the two stories here?
Two things: One, the directions in your link are for a "selector" switch, not a "disconnect" switch, two different functions.
Two, it states its for marine applications. I admit I know very little about marine applications, but the half dozen or so I have worked on were not a grounded system like on a travel trailer. In other words a metal frame was not serving as part of the circuit. A separate positive and negative wire was running to each device on the circuit. This is an entirely different situation than with a travel trailer.
Guy
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tomdrobin
Perry, MI
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I'm a retired mechanic and engineering tech. Either side will work. Most of the ones I've seen are made for the positive side. I can't think of any reason why though, as the points about shorting out if you touch a ground like the frame etc. are valid. I don't understand the arcing comment though. If something is drawing current, you can get an arc on either cable when connecting or disconnecting. Mine has an in line fuse right by the battery box. If yours is like that you can just remove the fuse to prevent draw on the battery. But, keep in mind the battery can self discharge with no wires attached. Approximately 1% per day at 70 deg F. and less the colder it is. I take my battery out and put in on a float charge in the garage. Then put it back in when I want to use my TT.
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Yahooligan
Temecula, CA
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tomdrobin wrote:I don't understand the arcing comment though. If something is drawing current, you can get an arc on either cable when connecting or disconnecting.
You are much less likely to get an arc/spark, if at all, when you do the ground last. Why? Due to the way electricity flows. There is little to no current flowing through the ground, all the load is on the positive side of the battery. Anything that produces a load on the battery pulls the energy from the positive side, by connecting the negative first the circuit is almost complete. Anything that is going to pull current will pull from the + side, and if it's substantial then you will get a substantial arc.
By connecting + first you avoid the potential for an arc, anything that is going to pull a load will still pull from the + side regardless of which is connected first, anything that makes its way back to the ground will be residual and is typically not enough to cause a spark. Electricity doesn't flow backwards here.
Also by connecting the - last there is no power spike headed towards your electronics, doing the - last means whatever is pulling a load only pulls what is needed for the load and not what is needed to arc, which is a lot more energy, which then gets fed into your electronics.
You'll be hard pressed to find any battery mfr that says NOT to connect + first and - last for all the reasons stated in this thread.
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HappyTrails2U2
Atlanta, GA
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4*phun*2 wrote:HappyTrails2U2 wrote:If you use this type you want to hook it to the negative post.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97853&xcamp=google&utm_source=googlebase&utm_medium=cpc&zmam=33951326&zmas=12&zmac=112&zmap=97853
Why?
'Cause that's what the directions say to do.
Greg
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