Safety relay question

Jim

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Of course you're right about the button, however you skipped a yr's diagram: the one that shows the safety relay switching ground: 1974. IDK, memory fails, maybe this diagram is wrong??.......
Yellow to one side of the coil, gnd on the other. Red from the solenoid to one side of the contacts, blue out the other... going to the start button. Gnd on the other side. Looks correct to me?
 

gggGary

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Of course you're right about the button, however you skipped a yr's diagram: the one that shows the safety relay switching ground: 1974. IDK, memory fails, maybe this diagram is wrong??.......
View attachment 233026
Good catch first difference I've seen from 74 to 75!
It DOES get a bit confusing as to how the 74 was wired...
The fiche claims same harness used 74-75

1672533625226.png

The factory manual really clears things up, LOL
KIMG2873.JPG KIMG2872.JPG 74-75 goofy diagram..jpg???
 
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lil2lo

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Below is a diagram from my manual. It's in dutch, so here's a little bit translation: veiligheidsrelais = safety relay, startrelais = start relay and startschakelaar = starter button switch.

Correct me if I'm wrong, but the starter button is not a ground switch in this case.
20230101_094256.jpg
 

gggGary

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Correct me if I'm wrong, but the starter button is not a ground switch in this case.
That diagram does show the start button on the+12 side. :thumbsup:
As far as I know North America has never had an XS650 wired like that.
Fun when guys in different markets trying to help each other?
Do you have those components?
Our 74 75 harness has an unused connector under the gas tank, but no one knows why it's there. Maybe the Euro market is the reason?
 

Adamc

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Thank you all for your replies. I thought about not running a safety relay at all. But I want to install a hidden starter button like the one on the photo below. My main concern is when this switch is defective there could be a permanent working starter motor. This happened once on an old Moto Guzzi I was riding, but then again Guzzi switches are notorious bad quality.

I thought about using a car light relay, but as I understand now this would not work because of the AC. I see there's some debate about whether it's AC or DC from the yellow wire. But this can be easy tested right? With a AC voltage meter and the engine running? Anyone done this?

I studied the wiring diagrams in my manual and it seems that the wiring of the safety relay changed over the years. On models 306, 366 and 476 the safety relay switches the positive wire to the starter button and from there it goes to the starter relay. On model 447 the safety relay switches the negative side with a wire coming from the starter button (which is now a ground switch) to the negative side of the starter relay. On models 533, 536 and 584 the safety relay changed back to switching the positive wire, but without a starter button in the circuit. The starter button remains a ground switch directly to the starter relay.

I don't think it makes much of a difference, but maybe with the starter button I plan to install it's best to mimick the 306/366/476 wiring. Any recommondations on that one?

View attachment 232975
I run my starter momentary switch through a MotoGadget M-Unit. No safety relays at all as the M-Unit is fully protected.
On the Revival switch the centre switch activated the starter.
I did once accidentally hit the start button whilst pressing the indicator (lower) switch with gloved hands.
Apart from a bit of noise no harm was done.
I have now rewired the switch so the starter is on the top button.
Ads.
Screenshot 2023-01-01 at 12.44.18.png

Screenshot 2023-01-01 at 12.38.15.png
 

jpdevol

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lil2lo

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Thanks for all the replies. One more question I hope you guys can answer is about the starter button switch. My local electronics specialist shop has two models that can be fitted with a waterproof cap. They have this small one (photo left), which is rated upto 3 amp. The one on the right is a lot bigger and can handle 30 amp. I prefer the smaller one, but I wonder if 3 amp is enough? I will be using a aftermarket solenoid from Heiden Tuning (XS650 specialist over here in the Netherlands), I think MikesXS also sell them. I don't know how much amp this solenoid draws. There are no specs listed on the sellers website.

1213a-2-drukknop-flash-off.jpg
e599-drukknop-waerdicht.jpg
2441.jpg


Nothing to do with my question, just to share info. At a classic race bike shop I found these lithium batteries from an Italian brand called Aliant. They have this model YLP12 which has 220 CCA and is small enough to fit in a tight place and it looks cool :). Gonna give this one a try.

Aliant-YLP12-Lithium-12v-12ah.jpg
 

Jim

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Starter solenoids are typically well under 1 amp draw on the energizing coil. The 3 amp switch should do just fine.

If you wanted to verify that, measure the resistance of the coil inside the solenoid and divide that into battery voltage.... that's your current draw.
For example: 12v divided by 100Ω resistance (on the coil) is about 0.12 amps of current draw.
 

dps650rider

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But, the circuit is more complicated than that. This is not wired like a typical 3 phase system. The 3 outer coil connections go to the bridge rectifier, the negative output of the bridge rectifier connects to ground and the positive to the battery via a fuse. The safety relay coil connects between the delta output of the alternator and ground. So any current going through the safety relay coil must go through the rectifier too. Not really sure what it would look like on a scope, since I have a PMA on my bike I can't check that.
 
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jpdevol

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So any current going through the safety relay coil must go through the rectifier too.
The ~5VAC that operates that relay's coil is not rectified, it comes direct from the stator
img041 (2).jpg
 
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dps650rider

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The ~5VAC that operates that relay's coil is not rectified, it comes direct from the stator

As I said, the current going through the safety relay must go through the rectifier to complete the circuit. One thing missing in your drawing is the ground connection for the safety relay coil, I have added that in the attached drawings.

In the attached I used red arrows to indicate the direction of conventional current flow where positive flows to negative. In reality that is not the case but it does make more sense when analyzing the circuit since the arrows in the diodes also represent conventional current flow. For both examples I just analyzed the output from one of the coils in the alternator for simplicity and used + and - symbols to indicate the polarity of that coil at 2 different points in time. The red arrows show the path that the current must flow to get from the positive end of the coil to the negative end.

Since in one of the directions the current must flow through the battery and the battery nominally sits at 12 volts I would expect the relay coil to see a DC voltage with an AC component riding on it. My bike has a PMA I can't use my scope to illustrate this.
 

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  • Pos Flow.png
    Pos Flow.png
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  • Neg Flow Flow.png
    Neg Flow Flow.png
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Grimly

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The safety relay is only seeing the positive going AC, as the neg-going side is blocked by the diodes in the rectifier, is that what you're saying?
I agree.
 

dps650rider

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Here is how mine is connected using a PMA and a shunt regulator rectifier. Please note that I have a series regulator rectifier but this setup does not work correctly using it. One of my "projects" will be to connect the safety relay coil across one of the PMA coils by adding some circuitry to limit the current. Hopefully I can find the time to do this before winter is over. :)

Anyway if you look at the drawing you can see that the safety relay is connected between one of the alternator outputs and ground. Based on that one might think it is AC going through the relay coil but that is not the case because of the action of the rectifier and shunt regulator. The other attachment is the actual waveform that the relay coils sees which in this case is pulsing DC as seen on my O scope.
 

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  • PMA Wiring.png
    PMA Wiring.png
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  • 2015-04-04_11-17-00 PMA Waveform to Safety Relay.JPG
    2015-04-04_11-17-00 PMA Waveform to Safety Relay.JPG
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