Re: [ST] headlight relay

[Frederic.Nizery@xxxxxxxxxx]

Hello all,

As the thread seems to be a long term one I finally have something to add.

I added whatever auto relayS to my sprint (2001) and to the one of my 
bro in law (2000)
two years ago w/ no adverse effect. I took whatever I found in an 
autoshop providing
that the contact numbers matches. The auto relays are obviously 
standardized and each
pin has a number corresponding to its feature.

The diode in a relay is for protecting the driving transistor from 
counter voltage impulse
when switched off. Yes there is a driving transistor. It's in the ECU. 
Most common
schematics for driving relays includes already the said diode. It's most 
of the time even included
in the transistor itself.

I don't want to offend whoever but I can't see how a diode in such an 
assembly could overheat unless
there is a deffect in which case it's more likely to burn a fuse.

For protecting against spark we put a capacotor in parallel. But in this 
range of use the contacts are supposed to be
hard enought to stand the spark caused by the air being a little ionized 
when the contact opens up.

If a relay overheat either the contacts offer to much resistance given 
the current crossing it, or the driving voltage
is too hight regarding the nominal voltage and the driving solenoid is 
getting hot.

For the first possibility aparently on the bike it was spoken about, 
there is one relay instead of two, that is 110w instead of
55w that is close to 10 A. Remember that when the engine is reving, the 
voltage is more 14v than 12v which is making us
a 10.5A roughly. If the relay is of poor building, could be the cause.

Regarding the second possibility, it's very unlikly that the founded 
relay has a nominal voltage of 6 volts but never know.

Whatever, get gently the cap off the relay and put it back on the bike. 
Then check by yourself what is hot, solenoid or contact.

Hope this clarify.

Fred 02 ST BRG
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