Master Switch

[Gupta]

This is the first time our university is participating in the fsae and we have very less background knowledge in this subject..so i just wanted to know the basic wiring diagram of the master switch..

[Gupta]

This is the first time our university is participating in the fsae and we have very less background knowledge in this subject..so i just wanted to know the basic wiring diagram of the master switch..

[PatClarke]

Gupta,
Please, please use the archives on this site. There is a 'sticky' post you should read before posting. Had you read this and followed the instructions, you would have discovered that the Master Switch and its wiring has been discussed many times before!
Pat

[A Richards]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gupta:
This is the first time our university is participating in the fsae and we have very less background knowledge in this subject..so i just wanted to know the basic wiring diagram of the master switch.. </div></BLOCKQUOTE>

I dont know what it is about people not reading the rules. ALL THE REQUIREMENTS OF THE PRIMARY AND SECONDAY SWITCHES ARE EXPLAINED QUITE CLEARLY IN THIS DOCUMENT. From that you can determine how you wish to wire your car.

[srikanth chilivery]

PatClarke,

I am too new to the team and the forum. I have searched the whole forum about the wiring of master switch. pLease Help where do I find these sticky posts.

[Ben K]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by srikanth chilivery:
PatClarke,

I am too new to the team and the forum. I have searched the whole forum about the wiring of master switch. pLease Help where do I find these sticky posts. </div></BLOCKQUOTE>

Go to the main Open FSAE discussion--the top of the page there are 'stickied' posts. Read them to get resources. Google and the Find feature are your friends.

Ben

[srikanth chilivery]

I have tried this one for the cockpit master switch and brake over travel switch.

Please help me if anything is wrong.

to the exterme left there is a power source( battery).

Image of my wiring (https://picasaweb.google.com/lh/photo/FNnJoJwln2aqpvrSogI9mtMTjNZETYmyPJy0liipFm0?feat=d irectlink)

1) then comes the push pull type cockpit master switch( i have written rotary which is wrong)

2) in series a brake over travel switch ( according to rules)
and finally my electrical supplies to the ecu ( which will cut the fuel)

Now my another doubt is where do I connect the other terminal to cut of the ignition system???

[Nicky]

Ummm... I'm not going to ask you to explain whether these are NC/NO switches. Neither am I gonna ask you if your ECU requires a +12V/0V signal to kill the fuel injection.

What I may tell you is that, one terminal of your coils require a continous positive supply(for 2-terminal inductive coils) while the other terminal is switched via a power-transistor(MOSFET,IGBT). The switching is controlled by the ECU which determines the dwell time(charge time) and the sparking commences as soon as the switch is turned off. Hope this helps you to figure out where the other terminal goes...

Peace out.

[TMichaels]

You should provide a sharp picture and maybe you want to use a free tool for wiring diagrams, like CadSoft Eagle.

I miss the master switch in your diagram and do you really want to route all your power directly through the CMMS and the BOTS?

Regards,

Tobias

[Rex Chan]

I agree with TMichaels: there needs to be a battery isolator switch (kill switch that uses a key, that goes on the right side of the car, that you see on EVERY FSAE car). This should be the first switch after the battery/alternator.

You should NOT route your battery wiring (up to 80A, not including starter motor) through the cockpit kill switch and BOT. You do realise this means big, heavy wiring up & down your car?

We just use a relay after the battery isolator. The relay signal side is controlled via the cockpit kill switch and BOT (in series).

Nicky's desciption of how fuel injectors and ign coils work is correct, though I'm not sure it relates to kill switch wiring... If you cut the +12V supply, nothing will run.

[srikanth chilivery]

Sorry TMichaels for the poor image,

My doubt is regarding the cockpit master switch and the brake over travel switch.

I have now uploaded a perfect paint image.
Our planning is as shown below link:

Image (https://picasaweb.google.com/lh/photo/4dMcNwEUh2eFhjjMWdFqxtMTjNZETYmyPJy0liipFm0?feat=d irectlink)

My Ecu works on 12 volt ( We am planning to use radedynamics ecu)

Please check the image and suggest me corrections and suggesstions.

the diagram is just an idea.

[Nicky]

@Srikanth: You cannot expect those two switches to conduct the entire load of the car through them. There are umpteen ways in which kill switches are connected to relays. Basically varying with their topologies.

Bottom line, the CMMS & BOTS are connected in series(Forming Logical "AND") to the control terminals of a relay.

For you, I'd suggest, get a relay with a 200Amp rating(Huge overkill, but in India a relay with rating of 60Amps is barely good for 25A). Plus you need to consider the cranking Amperage required. The control for the relay is to be given from the switches.

[TMichaels]

I always used a separate relay for the starter motor to separate current flows for EMI reasons.
I just formed a logic "AND" for the button controlling the starter motor by supplying it via the CMMS/BOTS relay.
But this was sometimes inconvenient, when trying to debug engine problems, since we had to manually disconnect the fuel injectors and ignition coils as the CMMS and BOTS had to be conductive for the starter motor to turn without firing while still wanting the ECU to be switched on.
As alway a compromise...

[srikanth chilivery]

Thanks Sirs.