[royce]

OK this is an idea I have been thinking of and it seems too simple so I must of stuffed it up somewhere

everyone would be aware that most forms of motorsport require a way for the entire electrical system to be isolated and the engine to stop when activated, not withstanding most people doing this wrong anyway usually you end up with a massive switch in a non ideal position and if tis required to work inside and out you have to muck around with cable and such

this setup I have cobbled in n00b cad should have the desired effect, and with teh solenoid near the battery should have minimal extra cable, one switch in the cab and one outside, wired up so if one isolates the other can still reactivate, basically wired how hall lights and so on are done in buildings

once isolated even the power to teh switches is still protected from a short (fused as well of course) but can still reactivate

I would use a duel throw switches to cut the ignition as well but left it out to keep my awesome cad work uncluttered

obviously the solenoid is drawing power when energised but on race type cars where they rarley sit powered for a long time I dont see it being a problem

anyone wish to pick holes in my theory?

[Scrawny]

Is that an aux. 12v battery by the first switch?

[royce]

no there is only 1 battery

[Scrawny]

So that circuit is still alive after the isolator switch is thrown?

[MacDaddy]

I thought a standard engine kill switch operated from the positive wire to the ignition coil...

But the way you have it it would kill engine and all electrics as well... is this for an offroad racer, or just your daily drive ?

[Scrawny]

Most motorsports require a complete isolation of electrics in case of fire etc. I would suggest this would be for a dedicated race car

[MacDaddy]

ScrawnC wrote:

Most motorsports require a complete isolation of electrics in case of fire etc. I would suggest this would be for a dedicated race car

Yep for sure, know about that... Yeah i was thinking it would be a bit much for a daily driver... lol...

[royce]

ScrawnC wrote:

So that circuit is still alive after the isolator switch is thrown?

yes but there would be nowhere for it to earth in a short as the earth is isolated, same goes for all other circuits really

the only part of the circuit that 'bypasses' the idolater is the earth for the coil side of the solenoid, but it cant help anything else to short anyway

you could run the isolator earth to the switched side as well but when you kill the electrics you wont be able to flick the switch to turn it back on you would need a seperate reset style of button, though rather than switches you could use a push button to kill it all, that could be a better option for something that its not going to get used on a lot

[Scrawny]

It would certainly save metres of battery cable , and associated voltage drop issues etc.

[Trojan]

royce wrote:

anyone wish to pick holes in my theory?

The only hole i could pick and would have to be checked with regulations. It's not a mechanical isolation of the circuit from a primary isolator. It's a secondary isolation via a control circuit and really not that much different then using the ignition switch on the inside..

[royce]

hehe checked, one of them rules where it doesnt say how, just that it must

[royce]

From the cams manual

10. Each automobile of the 2nd and 3rd Category shall be equipped with a battery isolation (master) switch which
isolates the battery and stops the engine. It shall be capable of being operated by the driver in his normal
seated position. There must be a second switch, or a remote means of operating the main switch, from the
vicinity of the base of the A pillar on the driver’s side or, for an automobile with no A pillar, in a comparable
position. This external device shall be clearly marked by a symbol showing a red spark in a white-edged blue
triangle of minimum edge length 150mm.

[Trojan]

royce wrote:

hehe checked, one of them rules where it doesnt say how, just that it must

I guess it comes down to how someone wants to read things. I can definantly read that both ways.

To me a "Master Switch" would be a primary isolation point and not a secondary like your above drawing, but that's just me. That there lies the problem, you only need that one person to read it the same way and it will cause you issues.


Any reason why you can't go with a standard type of isolation switch, mount that on the inside of the vehicle, then just run a pull cable from the switch handle to the outside and have it coming out through the vents at the bottom of the windscreen on the drivers side?

[royce]

Apparently in my lookings my idea isnt new, the V8supertaxis use similar

another 6m of 95mm2 cable to earth a battery is annoying and the pull cable is annoying and running the cable to the switch is annoying

plus the switch being a few meters from the battery allows for a situation where its possible for the earth cable to be 'compromised' and short to teh chassis which would then make the switch useless, this way the isolation is right on the battery so a lot more secure

trade off though like you are getting at is the solenoid possible isnt totally failsafe in not unlatching, though normal battery switches will stay on if the contacts arc and weld shut too

[Trojan]

royce wrote:

trade off though like you are getting at is the solenoid possible isnt totally failsafe in not unlatching, though normal battery switches will stay on if the contacts arc and weld shut too

Nothing is fail safe, i've had fail safe circuits fail.

Well if it's all good to go, then to answer your original question, then there is no reason why it wouldn't work. It's just a simple two way switching circuit of a solenoid, no different to how you set up two way switching of light switches in a house.

[royce]

I am going to sacrifice the mini to it tomorrow to see what happens

[Trojan]

I guess the only other issue, is selecting the right switch for the outside, so as not to confuse some of the numpties you will encounter working at a track who may have to use it.

[royce]

Jaycar have some big push button light up suckers, as long as its inside the correct blue triangle it should be ok

[bagnkat]

I'm not sure if I'm misinterpretting what you're wanting, but it looks to me like the two, two way toggles are forming a two way switch, like in a hallway. I would have imagined that if you'd rolled the car, could smell fuel and hit the isolator, you'd be less than happy if the solenoid was re-energised by a fire guard (doing what he believes is the right thing) and hitting the external toggle. I would have used a conventional emergency stop button that locks in the open circuit position when depressed, and twists out to reset. Then I'd just put both of them in series. Then to reset, you just have to twist both. If it's just you (the driver) that tripped the switch and you want to reset the system, it not an issue - you just twist your emergency switch. If the fire guard has tripped the system (perhaps seeing something you weren't aware of), you can't accidentally reset it.

If I've missed the point and you want it that way, apologies for waffling

[royce]

bagnkat wrote:

I'm not sure if I'm misinterpretting what you're wanting, but it looks to me like the two, two way toggles are forming a two way switch, like in a hallway. I would have imagined that if you'd rolled the car, could smell fuel and hit the isolator, you'd be less than happy if the solenoid was re-energised by a fire guard (doing what he believes is the right thing) and hitting the external toggle. I would have used a conventional emergency stop button that locks in the open circuit position when depressed, and twists out to reset. Then I'd just put both of them in series. Then to reset, you just have to twist both. If it's just you (the driver) that tripped the switch and you want to reset the system, it not an issue - you just twist your emergency switch. If the fire guard has tripped the system (perhaps seeing something you weren't aware of), you can't accidentally reset it.

If I've missed the point and you want it that way, apologies for waffling

Thankyou, thats exactly what I meant when I said it seemed too simple and was missing something

[bagnkat]

No wuckas.

[zookfun]

Not sure if I understand you correctly, but this will disconnect the earth from the chassis?

If that is correct, the car will still run, just not start...

[royce]

zookfun wrote:

Not sure if I understand you correctly, but this will disconnect the earth from the chassis?

If that is correct, the car will still run, just not start...

no it wont cause you missed the bit where I said I will use dual throw switches so at teh same time as the switch is turning off the isolator its also cutting power to whatever ignition circuit stops the engine running, in this case it would be the Injector pump

[Scrawny]

Isn't it the alternator you want to kill?

[royce]

the alternator is the problem part of isolating the electrics and in order to kill all the electricity you need to stop it charging, there are 2 ways to do this, either take out what it needs to keep charging which I think is the field connection and thats inside the alt or stop it spinning, which removing power to whatever keeps the engine running is a pretty easy way to do this

[Scrawny]

Thats what we do, just interupt the excitor wire to the alternator

[Scrawny]

How did you get on with this today Royce?

[royce]

it rained and I couldnt find a solenoid in my box of electrical shit so its on hold for a few months

[TZAR]

royce wrote:

it rained and I couldnt find a solenoid in my box of electrical shit so its on hold for a few months

what rain???????????????

That would be the shower head cause you are stuck in your apartment, cause you are to frightened of your gay neighbour putting the hard word on you again

[Scrawny]

I had a 120A start solenoid somewhere..... not sure if I still have it