[greywolf]

When a relay is turned off, the magnetic field in the relay coil collapses and the collapsing field passing through nearby wires induces a small current in them. If your relays are mounted right next to each other, they may be cascading down as each is inducing a current in the other. Being mounted near the wire feeding the neutral light would excite it. Mine were mounted vertically, one on each side outboard of the headlights and induced current in the turn signal wires. The turn indicator dash lights would flash when the high beams are turned on or off. Based on other reports of the indicator lights flashing, I'd guess others commonly did the same thing.

 

[rtb]

The turn indicator dash lights flash when switching the high beam after I installed an EB Dual Headlight relay kit. I didn't know why until now. Thanks Greywolf.

 

[waynestronach]

When a relay is turned off, the magnetic field in the relay coil collapses and the collapsing field passing through nearby wires induces a small current in them.

The first part of this sentence is correct. The collapsing field causes a high voltage in the circuits the relay is connected to. The voltage across an inductor is L*di/dt, i.e. the inductance*the rate of change of current. When you turn the relay off di/dt is high and high voltages result.

The best way to stop this is to connect a diode across the relay coil. The diode is reverse biased normally (i.e. bar to +), but turns on when the relay is switched off. These diodes are generally refereed to as back-kick diodes and are common practice in the electrical industry. They are very cheap and easy to fit, so would highly recommend that you do this to your relay kit as the voltages produced may harm the bikes electronics or your light switch (as the switch is opened the high voltage may arc across the switch). You should fit these as close as possible to the relay, i.e. ideally on the relay base.

For more information google "inductive kickback" or look at sites like Inductors - Inductive Kickback

 

[realshelby]

I just stripped off a piece of aluminum foil from the hat I wear all the time and fitted it around the relays. Instant Shielding from unwanted currents and alien listening posts.....

 

[greywolf]

Jim Davis at Eastern Beaver is aware of kickback in the kit but has recommended not adding a diode. Nobody has reported any harm from it but Jim said diode installation can shorten the life of the relay contacts.

 

[waynestronach]

The diode goes across the coil so not sure how this affects contact life ? I have installed relays which operate every couple of seconds 24/7 and expect 10 years + life with diodes.

Sent from my Garmin-Asus A10 using Motorcycle App

 

[greywolf]

I don't know the underlying theory, just what Jim wrote. See the last post at High Beam And Blinkers Activate W/Clutch Sw. Movement
He said relay life, not contact life as I previously posted.

 

[waynestronach]

Thanks GW, there are two possible effects. The diode carries the coil current for a short period of time, and discharges the magnetic field into the coil, i.e. some additional heating (but not much different to leaving relay on).

The second theoretical effect is that the current discharging via the diode will slow the speed of the relay contacts opening. I say theoretical as in practice the current will discharge via the free wheeling diodes in the regulator, so speed of opening will be the same.

Its my view that its this current discharging back to the regulator which is causing the indicator LED's to flash, and while separating wiring will reduce effect, the best way to stop it is to fit freewheeling diodes.

In an industrial plant, where the control system operates pumps, motors and other equipment and where reliability is vital for safety, reliability and profits, it is standard practise to fit diodes to every relay/inductor switched with DC.

 

[itsak9]

I'll try using the engine cutoff switch and see if that makes any difference.
Once I get back home next week, I will also try and shield the relay.
Will report back with the results.
Thanks for all the info!

Ray B.

 

[waynestronach]

Jim Davis at Eastern Beaver is aware of kickback in the kit but has recommended not adding a diode. Nobody has reported any harm from it but Jim said diode installation can shorten the life of the relay contacts.

The thing that doesn't add here is that diodes and relays are very cheap components especially compared to the rest of the electronics on board the bike. Its my view that even if this does shorten the relay life, I rather replace a relay after 5 years than have any other part of the bikes electronics fail. Each time you open circuit the relay without a diode you generate 100s of volts. I will test this and report back.

Does this cause failures elsewhere, well frankly the jury is still out. The damage mode is soft, i.e. each time you operate the relay like this you cause a little bit of damage to the electronics. Over time this may result in failures. To see if this is occurring you would need to look at the rate of electronics failures on bikes with relay kits without diodes versus those with no relay kits or relay kits with diodes. Of course if no bike with a relay kit has ever had a failure in its electronics then you are right there's no harm in it. I think that most people don't have any idea why electronics fail or what factors have contributed to the failure.