Headlight relays - back EMF diode required? - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
General V-Strom Discussion Talk about all things V-Strom not limited to just one of the above models

 2Likes
  • 1 Post By greywolf
  • 1 Post By ScottTheFalcon
 
LinkBack Thread Tools Display Modes
post #1 of 10 Old 09-10-2017, 04:09 AM Thread Starter
Stromthusiast!
 
ScottTheFalcon's Avatar
 
Join Date: Feb 2017
Location: Brisbane, AU
Posts: 121
Headlight relays - back EMF diode required?

Sorry to talk techie but...

I finally wired in my headlight relays today. I didn't use the Eastern Beaver setup because my setup (dash, DRL, spots, aux powerlet, USB chargers, voltmeter, battery tether switch, separate fuses for each headlight/beam) is a little complicated so I put it all onto a PCB mounted in a little sealed box under the front side cowling.

But, I notice a very small flash in both indicators (on the instrument panel) when I switch between hi and lo beam. My relays switch off and on when toggling between beams.

I'm a teensy bit worried I should have put diodes back across the relays to dissipate the back EMF when the relay coil collapses. Does anyone know if the Eastern Beaver relays, or other, use diodes for that purpose?
ScottTheFalcon is offline  
Sponsored Links
Advertisement
 
post #2 of 10 Old 09-10-2017, 05:40 AM
Super Moderator
 
p38arover's Avatar
 
Join Date: Jan 2009
Location: Western Sydney, NSW, Australia
Posts: 4,541
Some automotive relays have diodes already fitted inside, others have resistors across the coil.

An internet search on the relay part number should help determine what yours have - otherwise a check with an ohmmeter might tell you (no guarantee on that).

The problem with diodes is that it requires the installer to wire the relay according to the pin numbering correctly. The relays effectively become polarity conscious.

Personally, I'd add the diode. I don't know how effective a resistor is at suppressing the back EMF.

Ron B. VK2OTC
2007 Yamaha XJR1300

RIP Bucko
1979-2008 - Riding on forever
p38arover is offline  
post #3 of 10 Old 09-10-2017, 05:46 AM Thread Starter
Stromthusiast!
 
ScottTheFalcon's Avatar
 
Join Date: Feb 2017
Location: Brisbane, AU
Posts: 121
Yeah my relay's don't have diodes inbuilt - I checked because I've done the PCB layout differently (current flow direction through the coil) between hi and lo beam as it's pretty tight in the small space I allowed myself.

I'm not looking forward to removing the relay box to add diodes, but I think I'm going to have to. I don't like seeing other things being affected...
ScottTheFalcon is offline  
 
post #4 of 10 Old 09-10-2017, 06:03 AM
Super Moderator
 
p38arover's Avatar
 
Join Date: Jan 2009
Location: Western Sydney, NSW, Australia
Posts: 4,541
Scott, I just found this: Relays

Scroll down and read the bit on suppression and how the diode can affect relay speed. I learned a bit tonight - and I am/was an electronics tech.

Ron B. VK2OTC
2007 Yamaha XJR1300

RIP Bucko
1979-2008 - Riding on forever
p38arover is offline  
post #5 of 10 Old 09-10-2017, 11:06 AM
FORUM GODFATHER.....R.I.P. PAT
 
greywolf's Avatar
 
Join Date: Jan 2006
Location: Evanston IL USA
Posts: 38,049
Garage
There has not been a single report of a problem being created by the induced current from the relays throwing. Adding a diode can result in shorter relay contact life according to Jim Davis at Eastern Beaver. I think you have a solution in search of a problem. Every time time this is discussed, a lot of theory is put forth but there is no practical problem in using ordinary relays to power the headlights.

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
See https://www.stromtrooper.com/general-...nicknames.html

Please vote in the poll on what Strom(s) you have at https://www.stromtrooper.com/informat...-you-have.html
greywolf is offline  
post #6 of 10 Old 09-10-2017, 05:14 PM Thread Starter
Stromthusiast!
 
ScottTheFalcon's Avatar
 
Join Date: Feb 2017
Location: Brisbane, AU
Posts: 121
Quote:
Originally Posted by p38arover View Post
Scott, I just found this: Relays
Indeed an interesting read, regardless of whether or not I have a problem, thanks for that!

Quote:
Originally Posted by greywolf View Post
There has not been a single report of a problem being created by the induced current from the relays throwing. Adding a diode can result in shorter relay contact life according to Jim Davis at Eastern Beaver. I think you have a solution in search of a problem. Every time time this is discussed, a lot of theory is put forth but there is no practical problem in using ordinary relays to power the headlights.
The "read" above does indeed go into the "shorter relay life with a diode" and the reasons for. I'm not looking for trouble - or additional effort I was concerned about the flash from indicators on my instrument pod when either of my relays switches off. At this point I'll assume it's from the energy of the collapsing coil - the induced energy transferring over through all those wires running together in the left side switch harness. I'm just trying to prevent switch problems (and add features) rather than create different problems

I was wondering if this flash is seen by anyone else who uses relays for their lights. I've used beefy 40A relays because this circuit also powers my "accessory" circuit. I think Eastern Beaver uses 20A which of course is perfect for the intended use.

Last edited by ScottTheFalcon; 09-10-2017 at 05:33 PM.
ScottTheFalcon is offline  
post #7 of 10 Old 09-10-2017, 05:24 PM
FORUM GODFATHER.....R.I.P. PAT
 
greywolf's Avatar
 
Join Date: Jan 2006
Location: Evanston IL USA
Posts: 38,049
Garage
Everybody using unmuffled headlight relays mounted near the turn signal wires will get a flash on the LED indicators when they change beams. It's the nature of the setup. When I had LED turn signal lights, they would flash too. Again, there is absolutely nothing to worry about. The induced current is much too small to hurt anything. There has not been a single report of a problem.
p38arover likes this.

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
See https://www.stromtrooper.com/general-...nicknames.html

Please vote in the poll on what Strom(s) you have at https://www.stromtrooper.com/informat...-you-have.html
greywolf is offline  
post #8 of 10 Old 09-10-2017, 06:21 PM Thread Starter
Stromthusiast!
 
ScottTheFalcon's Avatar
 
Join Date: Feb 2017
Location: Brisbane, AU
Posts: 121
Oh good - so I won't climb in and remove my relay box, and get all "cat scratched" up again - good news



And before anyone mentions it - the fuses and relays are very easy to get at to replace, but the box mounting, well...

Lrobby99 likes this.
ScottTheFalcon is offline  
post #9 of 10 Old 09-11-2017, 05:03 PM
Stromthusiast!
 
Join Date: Aug 2007
Location: Omaha, NE
Posts: 7,543
I wonder

Would a capacitor across the terminals allow the transient to go to ground? Probably less likely to present problems down the road than a series diode. A zener diode across the terminals would also clamp the voltage. Depending on the resistance of the coil, a series resistor would also help limit current.

Or you could just leave well enough alone. LED's can take a pretty high current transient, so long as the duration is short. The failure mode seems to be thermal.
Jimding is offline  
post #10 of 10 Old 09-11-2017, 05:05 PM
FORUM GODFATHER.....R.I.P. PAT
 
greywolf's Avatar
 
Join Date: Jan 2006
Location: Evanston IL USA
Posts: 38,049
Garage
Much ado about nothing.

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
See https://www.stromtrooper.com/general-...nicknames.html

Please vote in the poll on what Strom(s) you have at https://www.stromtrooper.com/informat...-you-have.html
greywolf is offline  
Sponsored Links
Advertisement
 
Reply

Tags
headlight relay

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome