another coil relay gone bad prematurely

[don_gibb6512]

This is what I just installed: http://www.partsexpress.com/pe/showd...number=330-070

Mounted it under the tank, on the frame with a zip tie, nice and tight. No apparent vibration but also no ventilation. It seems a bit warm from the heat off the top of the engine but nothing out of the ordinary. I don't have 200 miles on this relay. What gives? Just bad luck? I'm going insulate it from the frame with a piece of rubber the next time but would it help if I mounted it where it could get air? I have one mounted on the front of the bike for the horns and it's over 3 years old and still going strong.

[seuadr]

i dunno, personally, i've mounted mine at the battery box. the only failure i've had was the fuse popped when i accidentally grounded out a connector :P

[82Shafty]

I went to the homie G section at Auto Zone ( neon lights ) and found a no name China 40 amp relay there.

I've put over a 1000 miles on it so far and all seems well. I did my dad's bike the same way and his seems fine, both are mounted by the fuse box.

[chef1366]

homie G section
LOL

[salty_monk]

Mine is by the battery box. Cheapy relay. OK so far at 2200 miles but I do carry a spare just in case.

[srsupertrap]

I mounted my Parts Express relay on the Electrical Panel, I guess I better buy a Spare

[salty_monk]

That panel is also rubber mounted & cool... should be fine there

[Big N daft]

I've often wondered why we don't use a thyristor here instead of the relay. No moving parts to worry about being shaken loose and quite cheap. It would be quite a simple job to mount it to the frame and use some thermal compound or a pad to improve heat dissipation.

Which makes me think that it seems strange that no one here has tried it!

[seuadr]

it's my understanding that they opperate on high voltage AC applications. not sure it would work with low voltage dc.

for that matter, you could just get a solid state relay for about as cheap as you can buy the normal relay for.

[Big N daft]

it's my understanding that they opperate on high voltage AC applications. not sure it would work with low voltage dc.

for that matter, you could just get a solid state relay for about as cheap as you can buy the normal relay for.

It's been a long time since I meddled with electronics at component level but I was pretty sure a thyristor was effectively a switched diode and would operate on DC. I'm also pretty sure you can get them to work at lower voltages as well

But thinking about it you wouldn't really need a SSR you could quite easily knock up a MOSFET (or whatever modern equivalent you can think of) as a simple trigger device with a couple of resistors and you'd have a quite robust solution that would be vibration proof to a greater extent than a relay

[seuadr]

fair enough, but i think it's heat, not vibration that is killing these relays, i haven't had any trouble at all with mine, and it was a cheapie. but i have mine near the battery box. most of these i've seen failing are near the motor.

[don_gibb6512]

fair enough, but i think it's heat, not vibration that is killing these relays, i haven't had any trouble at all with mine, and it was a cheapie. but i have mine near the battery box. most of these i've seen failing are near the motor.

I think I agree. I'm going to dissect the one that went bad to see if I can find out what happened. I'm feeling less than confident on creating a single point of failure like this in the ignition circuit at this point.

[p_s]

The three of mine that failed were by the battery box. I tore apart all 3 and on all 3 the tiny wire connecting the coil to the terminal had broken. Vibration killed them. So I spent $100 on a new ignition switch and don't worry about it anymore. And BTW for most models (but not mine) there are cheaper aftermarket ignition switches. I think ~ $30. Might be worth a shot.

[salty_monk]

Very good.. except I lose a volt through ignition, another through the kill switch & a third one through the loom itself! Not practical to replace that lot!

I'll try to post a pic of my install at some stage. If you use a relay socket when you fit it then it is really easy to switch them out... carry a spare as I do.

Dan

[seuadr]

I think I agree. I'm going to dissect the one that went bad to see if I can find out what happened. I'm feeling less than confident on creating a single point of failure like this in the ignition circuit at this point.

that's why i didn't cut any wires to install mine. if i have any failure of the relay and i don't have a replacement, i can simply revert the wiring to stock