Q:Best way to secure CDI spark ground via ignition SW? GT500

[Nicholas]

Hi all,
I am just planning to re-wire my bike and adding a few modifications, ditching the key and using RFID. Like the key I would like to activate the two isolated circuits:
1. Battery - provide fused 12V to electrics.
2. Ignition – close a NO switch inserted on the GND line of the coil, right before the mechanical kill switch.

I have my latching circuit worked out and 1 should be pretty easy, switched on via a 30A fused EM relay. But I am scratching my head on the best way to secure 2.

If I am right, you basically kill the GDN line of the coil and the bike will not start. So I need a switch that can be controlled by the output load of the RFID latch.
Great! I can use a relay! I think I understand the pitfalls and wanted to run them by you here.

So I would use a mechanical (EM) NO relay to close the switch when latched, but could this be unreliable when the bike is in use and come apart when riding through a bumpy road? Ideas?
Possibly keep the coil charged for a NC relay and then short-circuit the coil when it is active?
Or could I use a solid state (SS) relay?
I have been avoiding these as they apparently get hot under large loads. I am also not sure it would be a good idea to use a resistive switch for the coil, could it affect the spark quality?

In the end I want to be able to secure the bike by cutting the ignition (a.k.a coil) when it is switched OFF.
A SPDT ignition key would make life easier, but I like doing things the hard way....

[jabcb]

The GT500 wiring diagram is here: viewtopic.php?f=29&t=4743&start=8

You should make a diagram of your proposed configuration.

The bike basically has two kill switches that ground a connection on the CDI unit.
One is the ignition switch & the other is the kill switch.

The ignition system is not powered by the battery.
Your proposed ignition switch relay would not carry much current. Have three scenarios:
1) When your RFID system powers the relay to the on position, the relay would be open & not carry any ignition system current.
2) When your RFID system stops powering the relay & the relay switches to the off position. The relay carries some current until the engine stops spinning.
3) When the bike is off, the RFID system isn't powering the relay & the motor is not spinning. The relay doesn't carry any current.

I see two issues:
1) the RFID system is always on & the battery powering the RFID system isn't very big.
To prevent the battery from being completely drained, you should include a switch to turn off the RFID system.
2) interference in the RFID signal.
If something interferes with the RFID signal then your motor switches off until the interference is gone.
Annoying at the least & possibly dangerous.

[Nicholas]

You should make a diagram of your proposed configuration.
The bike basically has two kill switches that ground a connection on the CDI unit.
One is the ignition switch & the other is the kill switch.

thanks I will, and thanks for clearing my confusion with the GND, I had it the wrong way around. You make the connection to GND to kill the engine, ok, got it! so, I can just energise the relay when ignition is on to break the kill switch relay. cool!

I've done an initial diagram on paper and will digitise it shortly...laptop giving me grief..

So WRT the issues:

1) the RFID system is always on & the battery powering the RFID system isn't very big.
2) interference in the RFID signal.
If something interferes with the RFID signal then your motor switches off until the interference is gone.
Annoying at the least & possibly dangerous.

1) I was thinking of hooking up a timer to the brake switch to activate the RFID for 20sec
2) I didn't think about this....I didn't think the antenna or output pulse would cause any interference. Have you heard about this before? The circuit sends pulses and I have wired up three relays to implement a toggle pulse latch. When you cut the power, the latch resets.

[jabcb]

If the bike is running & you walk away, do you want the bike to shut off?

For #2, I was thinking the RFID needed to be present to keep the bike running. If you walk away, then the bike shuts off.
Then the concern is interference from another vehicle ( or construction project, etc …) masks the presence of the RFID & the bike shuts off.

An interesting solution might be:
1) if the bike is running you shut it off with the kill switch
2) if the bike is not running, using the front brake activates RFID for 20 sec
& if RFID is found, then relay trips to allow bike to start
3) relay in #2 powers itself so that it stays tripped until motor is shut off via kill switch
Looks like your toggle pulse latch could work for this.

[jabcb]

A simplification to the wiring would be to add a start button.
Press the start button & the RFID works for 20 sec.

Will be interesting to see how this works out for you.

[Nicholas]

Well I will hook up some sample circuits over the weekend. But I am now scared of using an EM relay between my coil ground. I don't have experience in this area to know what is a serious risk or not, but are automotive grade relays created equal? I don't think so and it comes down to application.

If I'm relying on this relay to keep my engine running then I need I be sure it can withstand external factors such as vibration and heat. It's the former that concerns me as if I'm riding on a bumpy road, could this cause the relay to fail and release its magnetisation? If so then that is dangerous.... This is why I was thinking SS relay...

I just started looking up some specs and the Panasonic automotive relays can handle about 4.5G of vibration before they may fail....not sure if that is a lot in the space of vibration?

This is what has me a bit puzzled and enough to go back to using a Key...

I would have used the RFID circuit to start and stop the bike. I have designed a three relay latch that can toggle from on and off based on subsequent pulses. So ideally I would swipe to turn the ignition on and off again. I will also add a few override switches in some hidden locations.

[jabcb]

Don't know what the max voltage for the primary side of PEI is.
But per Wikipedia, primary side for CDI ranges from 250 to 600V.
http://en.wikipedia.org/wiki/Capacitor_ ... e_ignition

The SS relay will have to deal with these high voltages for every spark.

[Nicholas]

Don't know what the max voltage for the primary side of PEI is.
But per Wikipedia, primary side for CDI ranges from 250 to 600V.
http://en.wikipedia.org/wiki/Capacitor_ ... e_ignition
The SS relay will have to deal with these high voltages for every spark.

Wow, that sounds nasty, the alternator GND is another line that could be broken. I'd imagine this wouldn't suffer high voltages, I'll have to ask the power dynamo guy as I've bought one of their kits.

I did mention my concern about the relay and he seemed to think failure is quite uncommon with "their" relays....so how do modern bikes deal with this? Isolate the starter motor?

This is my new alternator, so I could also put a relay on the brown wire out of the alternator to the coil.
http://www.powerdynamo.biz/wiredias/72ik_102.pdf
http://www.powerdynamo.biz/eng/systems/ ... 17inst.php

[tz375]

Disclaimer: I don't know much about electronics and what I'm about to suggest may be as dumb as rocks, so treat this with caution.

Looking at the GT500 PEI circuit, it looks to me as if the kill switch is connected to the exciter coils only, and should only carry a relatively low voltage. The capacitor that stores up the 200-400V is "after" that point in the circuit so to speak. Do check that with someone who knows WTF they are talking about though

If I'm right, you could use a regular NC 5 pin relay so that without power, the circuit is grounded so it cannot be started. Have the RFID apply power across the relay to Open it and allow the bike to run. Relays are used extensively on cars and bikes on ignition and lighting circuits and drop out from vibration is not a common mode of failure.

What you will have to do though is to work out how to run the bike if the RFID system battery dies. Maybe the stock ignition switch (theft prevention) wired to a SPDT to allow the use of either RFID OR the key (wired in parallel).

Pretty simple - which probably means I missed something

[Nicholas]

If I'm right, you could use a regular NC 5 pin relay so that without power, the circuit is grounded so it cannot be started. Have the RFID apply power across the relay to Open it and allow the bike to run. Relays are used extensively on cars and bikes on ignition and lighting circuits and drop out from vibration is not a common mode of failure.

Yes, this is exactly what we are thinking, like the ignition switch. The RFID output will activate a latch that will hold constant +12v to control either one or two relays, so a DPDT with one pole NO and other NC. I would wire parallel with the kill switch so that either would serve it's purpose. You are right about the failure, I am being too cautious about it failing due to viabration...what do they say about too much information?

What you will have to do though is to work out how to run the bike if the RFID system battery dies. Maybe the stock ignition switch (theft prevention) wired to a SPDT to allow the use of either RFID OR the key (wired in parallel).
Pretty simple - which probably means I missed something

Yes that is a good point. I suppose I could just pull out the relay and we would be back into the hands of the kill switch. Or I could use a normally open switch that is held shut by the battery (possible drain) so if the battey is dead it is opened, but this would be less secure? In the end I am not so sure this will be any more secure than a key.
I'll think about a few different circuits and give some a try, if its all rubbish I can go with an "old fashioned" key.

[Nicholas]

OK, I started the engine last week 3 kicks and it was alive and sounded just amazing. I need to do my wiring, will phase it...not sure I'll add the RFID yet, but going with a few relays. This is my wiring with the Powerdynamo alternator kit, btw it is an amazing kit and very easy to install!

Shame, you cannot upload larger resolutions. Let me know if I have done something wrong..or crazy...like chamfer piston skirts!

Suzuki Wiring PowerDynamo 1200.jpg