Relay Failures

[Kiwi Dave]

On my 2002 Le Mans, I checked the wiring diagram against the colour codes going in to the relays and found the following:-

 

Counting from the front,

1. Start Relay

2. Lights Relay

3. Sidestand Relay

4. ECU Relay

5. Injector Relay

 

Now, I gotta work out some way of labelling these .....

[docc]

Vinyl stick on letters from the hobby store. "S", start; " L", lights; "C", computer; "F", fuel.

 

The black one is an upgraded Siemans which I put in the "side stand relay" slot as it is the least stressed. It is actually activated by the neautral switch not the side stand switch.

 

I put a couple of the original Siemans in a bubble bag and slid them into the tail cowl storage just in case . . .

 

 

I measured voltages today: 12.72 v at rest, 13.0 after running a few minutes at idle and 13.98 v at 1800 rpm and up.

 

This means the 60 watt hi beam will draw less amperage than it would at 12.0 volts ( 4.3 amps versus 5 amps at 12.0 volts). Less current is good news.

[dlaing]

I believe it will draw the same amperage, but the wattage will go up when the voltage increases.

The 55W rating is kind of theoretical and the actual wattage depends on the available voltage while current is flowing and manufacturing tolerances.

[docc]

Oh no! I was taking the wattage as a constant such that the current would vary with voltage.

 

(edit:)

So, it is true. I consulted a professor of physics ( best I could do) and found that there are no constants in the equation. Voltage goes up= wattage goes up= current (amperage) goes up.

 

It's probably reasonable to assume that the wattage for 12v devices is rated at 12.7 volts which is the widely accepted standard voltage for 12vDC lead-acid battery systems. In that case the guzzi's 13.98 charging voltage will increase current through the harness about 10%. So the 60 watt hi-beam will burn at 66 watts and draw 5.5 amps.

 

The charge voltage should diminish as the system comes to full charge but probably never drops below 13v.

 

I wonder if bikes suffering relay failures are running much higher voltages? A bad regulator will eat the other electrical components in the system and tend to force electrolyte out of the battery ( which has been reported by some riders).

[dlaing]

I know several of us have added horn relays. But has anyone added lamp relays ( I'll bet they'll burn the headlamp brighter with a good guage of wire to them)?

I just finally noticed this article on Guzzitech dot com:

http://www.guzzitech.com/Lighting-kurtz.html

It shows a 1976 LeMans before and after adding a dedicated lighting relay.

I am pretty sure we won't see as dramatic of a change but I am sure it will be an improvement.

If we add one relay for high beam, one for low beam, and one for the horn, the original lighting relay, year 2000 starter relay, and 2001+ year key switch should get a nice break.

Heck, our lighting and horn may both become more bright and loud.

I just hate strapping more wires to the frame.

The lighting relay will probably fit in the headlight housing, and the horn relay can fit behind the horns.

 

Ooops, you and the physicist are correct, not only will wattage rise, but amperage will also rise as voltage rises. I believe the other factor in the equation, resistence will drop as voltage rises across a filament, but probably negiligibly.

[docc]

I used a pair of the original Siemans relays for the Fiamms strapping them along the right side of the spine and routing the stock horn wires to them. Pretty clean really. biggest trouble is adding more terminals to the stack on the battery and tucking in another fuse holder.

Does anyone make a relay that the headlamp connector would plug directly to?

EDIT: November 2006: After a few years the Seimens relays began to crap out and I replaced them with the Bosch which I pulled out of the block to make room for the GEI set.
Back to LOUD horns.

 

EDIT: February 2014: Still using those two Bosch relays for my FIAMM horns.  GEI in the relay block have given way to OMRON relays which are the absolute best of the best.

[Kiwi Dave]

I believe the other factor in the equation, resistence will drop as voltage rises across a filament, but probably negiligibly.

 

Actually, it's the other way around, the filament has a positive temperature coefficient. As the voltage rises so does the current which increases the temperature and thus the resistance (which of course reduces the current).

 

The difference can be quite significant, and this is why most lamps blow on switch on due to the rush of high current through the low resistance presented by the cold filament. Lighting operators in television and theatre often "preheat" the filaments at low levels to avoid the high current rush and the likelihood of a failed luminaire.

[dlaing]

Thanks Kiwi Dave, my brain wasn't working right. I was thinking of the current dropping as the resistance INCREASED.

 

Would the difference in resistance be significant between 12 and 14 volts?

[Kiwi Dave]

Would the difference in resistance be significant between 12 and 14 volts?

 

The only way to know would be to measure the current at the two voltages to calculate the resistance. I wouldn't expect too much of a change.

 

However the life of the bulb is significantly increased running at the lower voltage; not that this is an issue.

[docc]

The AMP connnector for the headlamp can be opened and the individual connectors fastened to the relays ( these are 30 amp), one each for the hi and low beam. They will fit in the headlamp shell but I padded them with a thin sheet of closed cell foam to avoid damaging the back of the reflector.

 

Now to run a 16 guage hot from the battery. I'm working on a junction block to get that stack of terminals off the battery. More on that tlater.

 

Here's a photo of the harness modification :

[Kiwi Dave]

I'd be curious to know whether the addition of the relays for the lighting circuits significantly increases the amount of light output from the headlight.

 

Any chance of measuring before and after, docc?

[docc]

The only meaningful measure I could think to use is ' voltage drop.' I guess I could point the thing at the garage door and do a 'before and after' like the link we saw. i'm not expecting a brighter light(would be nice though) just hoping to enhance reliability and preserve my switches.

 

Spaghetti in a bucket:

[docc]

And the changes under the seat : ( all soldered connections , heat shrink and a b'zillion zip-ties):

[docc]

Dave,

 

WOW! Those lights are bright! And the horns are loud , too. Of course doing this in the garage kind of skews the impressions.

 

The actual voltage drop at the headlight connector is half . But since the original voltage drop was 0.7 % this should add up to a whopping 1/2 watt increase in the lamp.

 

I really don't think the light's any brighter. But I did put a 5 amp fuse in the main block for the headlamp circuit ( it was a 15 amp) so I'm still hoping to save any relay or switch failure in the long run.

 

So far no smoke to try and get back in the wires.

[dlaing]

Smokin'!

Maybe if you ran the lighting through Nology plug wires they'd shine brighter

I like your junction boxes.

Are those standard radio shack issue?

If you hold the high beam flash on, (so that the low and high beams are both on and you are pushing maybe 9 amps)does it blow the 5 amp fuse?