DIY - Double Crank Prevention


Thread Starter #1
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Friends,

I'm planning to make Double crank prevention circuit for my friend's 2001 model Hyundai Santro LE.

Here is the circuit diagram in my mind.

Circuit.jpg

Please suggest me how should I take the signal for NC relay. My intention is once the engine is running (i.e., alternator is running) a signal from alternator should open the NC relay, preventing current flow to starter solenoid.

I worry if I take the signal directly from alternator, even during cranking this circuit may get opened (during cranking alternator starts supplying current)

Help me out guys.
 
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Hi Mr.Boss, I hope this DIY will be easy to copy (I too am interested in this) can you please share a photo of the relay you are using. I have no idea about this relay & connections sorry [:)]
 
Thread Starter #3
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Hi Mr.Boss, I hope this DIY will be easy to copy (I too am interested in this) can you please share a photo of the relay you are using. I have no idea about this relay & connections sorry [:)]
I don't have the relay now (yet to purchase)
It is a regular NC (Normally Closed) relay in operating voltage of 12V.
 
Thread Starter #5
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Guys,

One more clarification, what will be voltage from alternator at cranking rpm & during engine running condition (I think at engine running condition it should be 14V+, please correct me if I am wrong)

Boss This is an awesome project. long waiting and I am also interested in this.
Thanks dude. Hope to complete it by this weekend.
 

Varun560061

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The voltage at idle would be 14.4 volts with out any load.

I have an idea, connect the +ve from alternator so that it can be used as a signal the use the relay as you said.
 
Thread Starter #7
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I worry if I take the signal directly from alternator, even during cranking this circuit may get opened (during cranking alternator starts supplying current)
I have an idea, connect the +ve from alternator so that it can be used as a signal the use the relay as you said.
This is why I asked for voltage from alternator at cranking speed. If it is 12V, then I should use a 14V relay (may be a 12V NC relay with resistor to convert it to 14V)
 
Thread Starter #9
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But I guess, 12volts relay can take voltage upto 14volts. You can give a try.
Dear, I agree. But my concern is, if I use a 12V NC relay taking signal from alternator and if the output from alternator is 12V at cranking rpm, the circuit will get opened at cranking rpm itself (even before the engine fires) and there wont be any supply to starter motor. We will end up with n number of partial cranking without starting the engine.
 

sethumurugan

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Wow, That is great bozz. My sparky when the engine is running and in idle no one knows that engine is running [especially from inside] So many times I have cranked twice without knowing that engine is already on. After that I used to make sure all lights in dash are on [When the engine is running those lights will go off] before starting. But some times I forgot to look into dash and cranked and fund the engine is running.

Do we have any product as such to do this job since am so scary about doing DIY in this area.
 
Thread Starter #11
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Do we have any product as such to do this job since am so scary about doing DIY in this area.
I don't think there is any such device available.
Let me give a try for this project and let you know, may be we can get it done from a technician.
 
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I don't think there is any such device available.
Let me give a try for this project and let you know, may be we can get it done from a technician.
My modified Design for you and i hope it works.[;)]
Things you need
1, SPDT RELAY 12volt 40-50amp
2, Vacuum Switch
3, Solenoid Valve 12volt (should be closed when the power is applied and open when the power is removed)

Circuit.jpg
 
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