Battery cut-off

[Jerry]

Any thoughts on them, and how did you mount yours. I am having  a tough time coming up with a mounting idea that makes it difficult to prevent someone from just removing the nuts on the switch and connecting the two wires together, thus bypassing the switch. Any thoughts or pic's . Would be helpful..

Thanks Jerry

[Yummi]

I use a master shut off that is behind the passenger seat.  I am not worried about security, just safety -in the event somebody needs to be able to disconnect the battery from outside the car.   It mounts through a panel directly above the battery area. 

 The only picture I have is this one.

[Jet]

Jerry, theres always away around everything, your best bet is to put a hiddle switch in the wire loom somewhere.

also, put the battery cut off switch in line with the negitive lead.

[Jerry]

The idea of have the switch is to prevet battery drain (and some security) so if it goes on the neg cable how does that help? I like the idea of the hidy switch.. I am also going to pull the fuse for the starter when it sits.

[Admin]

The idea of have the switch is to prevet battery drain (and some security) so if it goes on the neg cable how does that help? I like the idea of the hidy switch.. I am also going to pull the fuse for the starter when it sits.

You have to have negative to run, drain power etc... Not sure why he suggests negative cable, But makes sense, Im sure he will explain further...

[Jerry]

I not think the neg cable idea will work for me, because i have a few spots around the vehicle that i have made grounding points so that i do not have to run wires all the way back to one location for a ground. That way if i have an issue i only need to trace the hot wire back to the fuse panel.

I have to use the pos cable or some of my switches  ( lights,fuel pump,cig lighters ) will always be hot thus a possible drain.

I am right

[trojan]

Onya Jet, good one mate

Jet's talking about the lead that comes from the battery not the different grounding points and it REQUIRED in some classes of racing.

Don't rely on "cutting power" as a security measure if security is a concern. use a cheap immobiliser if you are really concerned about security.
Battery cutoff is a SAFETY device NOT a security device

[Jet]

Yes, Run the switch inline with the lead from the battery to the frame, that way its not live if your working around it etc, As mr trojan said, in some racing putting it on the negitive side is required.

[artie on edge]

and... the reason behind negative terminal isolation is a safety issue.

Liken it to disconnecting a terminal on the battery. Would you remove the positive or the negative when doing so? Most will disconnect the positive....wrong.


With the positive terminal off, the entire chassis is still 'live' (for want of a better word), it is still connected to the battery and therefore still part of the circuit (although no current is flowing).

Any metallic object can still short out to ANY part of the chassis if it touches the pos terminal, perhaps a dropped spanner OR a bent/displaced piece of piece of tubing in a crashed buggy. This is why racing requires a negative isolater in Aus.

Disconnect the Negative terminal and the circuit is open (the same as before) BUT the chassis is dead and no longer part of the circuit, accidental short circuits are nearly impossible.

And, this IS NOT my opinion, its part of the laws surrounding motor racing in Aus... Happy Bar Mitzvah!

[fabr]

I guess I'm stoopid. If the negative lead is disconnected you still have potential current flow if any hot lead makes ground from a dropped wrench or anything that will complete the circuit. If the positive  lead is cut close to the battery it prevents any possibility of current flow from the disconnection point on. WTH would it be better to cut the negative or do you ozzies use positive ground systems? I agree to stop a spark in the event of cutoff cutting the negative is ALWQAYS the proper procedure but to prevent current flow the positive is what needs cut.Same as in a 110V circuit you ALWAYS switch the load(+) leg. Makes no sense to cut the ground circuit since the circuit will stilll be live.Inoperable BUT LIVE.

[Jerry]

Call me stupid too, my thinking is following Masterfabrs. Please help me understand this

[Yummi]

Cutting either works - once it is isolated, it is no longer a complete circuit.  The negative might be a fine call. 

I did positive but i thought - well, here is one more lead to fall off and arc around........  so i loc titied it up and went about my business.

[fabr]

BS if the positive is still energized there is the potential for current flow.Take for instance, you have an accident and a sheetmetal panel touches the neg terminal of the battery. If the negatyive cable is the cutoff it is of no use since the body panel is now the ground circuit-current flows,sparks and ignites leaking flammables. Not possible if the positive cable is the disconnect.Glad I'm not in Ozland.You guys do everything bassackwards! LOL!!!

[Yummi]

what you just described is completing the circuit - that can happen on either side - cutting the circuit is the goal.   (Dang, and I usedd my "smite" for this hour - rats!)

To the extent that doing so on the negative side allows for only one main positive lead with no breaks to the starter, it might be better than having an effective junction on the positive side.   

[fabr]

How you figure? Current flows FROM the positive TO the negative. If the positive is switched close to the battery there is NO WAY for a problem.Put the switch within 6" of the battery and run a cable to the switch.Simple and nearly impossible to have any short circuits anywhere.Electrical code in the US REQUIRES the switch on any circuit to be on the LOAD(+) side of a circuit for the very reasons I just gave. I understand that code applies to AC but the principles are the same.