Headlight relay question

[BerndM]

I want to make an electrical change to my 2013 DCT headlight function, and I need your collective input.
I would like to add a relay to the bike so that the headlight does not come on as soon as you turn on the key, but only after the bike has started!
I find it absolutely asinine that Honda would put a whopping 55 watt load on the poor battery in addition to the starting draw.
What I need to locate, is a connector or wire somewhere on the bike that ONLY becomes "hot" after the bike is running.
There must be something like that somewhere, I hope.
Thanks for your thoughts!

 

[zirconx]

One of my past bikes did this (Kawasaki Concours I think) and I thought it was a great idea. I've often thought about doing this on my other bikes.

One way I thought of would be to tie a relay into the oil light. When the oil light is on, it powers a normally closed relay, so it turns the headlight off. Might need 2 relays, one for high beam and one for low, unless you tap into the source wire that feeds both. Or if there is a single ground wire from the bulb (and no chassis ground) you could use a single relay there.

Another way, and the way that some bikes actually do this, is to power a relay directly off the AC coming off the stator. I'm not sure if they use a diode in this circuit or if the AC will just keep the relay energized, I think it will.

Another way I thought of would be to trip a latching relay when you press the starter button. This assumes that the bike already turns the headlight off during cranking, I'm not sure if it does.

 

[BerndM]

Hey zirconx

Thanks for your quick response.

My last 3 bikes, all BMW's, kept the headlights OFF until after the bike was running. To me this is ultimately logical.

BTW...I just went out and checked my bike based on your response. The headlight does NOT turn off during cranking. Neither the low OR high beams!!
If the headlight currently (pun intended ) uses a relay, then my focus will be narrowed to finding a new circuit, connector or wire onto which to attach the relay's trigger wire.
It would be that simple, if such a circuit exists.

 

[zirconx]

I'm sure it's on a relay, but I doubt it's by itself. Have you looked in the fusebox, is there a relay in there labeled headlight?

 

[showkey]

That is interesting..........the NC does not turn the headlight off during cranking.........many other Honda's do.

BUT not sure it really matters all that much in the long run. ??????

 

[670cc]

That is interesting..........the NC does not turn the headlight off during cranking.........many other Honda's do.

BUT not sure it really matters all that much in the long run. ??????

Apparently Honda is OK with it.

 

[Brillot2000]

I want to make an electrical change to my 2013 DCT headlight function, and I need your collective input.
I would like to add a relay to the bike so that the headlight does not come on as soon as you turn on the key, but only after the bike has started!
I find it absolutely asinine that Honda would put a whopping 55 watt load on the poor battery in addition to the starting draw.
What I need to locate, is a connector or wire somewhere on the bike that ONLY becomes "hot" after the bike is running.
There must be something like that somewhere, I hope.
Thanks for your thoughts!

Let me look into this in the next couple of days. As I have a DCT model and I am an Electro-Mechanical Engineer. I will study a few items and get back to you if it will be possible without heavy modifications and "Hacking Up" the wiring harness. "Hack Jobs" can cause additional unforeseen issues. Hold off on doing anything for now.

I suggest that you also look into a LED H4 Bulb Conversion, like I did. It only draws a little over 2 Amps in either "Low or High" beams. That's anywhere between 25-30 Watts depending on the voltage and current at any given time. I'd receommend going with one that looks like configuration shown in the images below. Try this website LED H4 Headlight Bulb. It will certainly will help with your current draw concerns.

 

[dduelin]

It's a choice of course to wire up a relay but in the long run having the headlight on when cranking does not seem to cause starting or reliability issues. Honda has a pretty good reputation for figuring stuff like this out.

 

[Brillot2000]

It's a choice of course to wire up a relay but in the long run having the headlight on when cranking does not seem to cause starting or reliability issues. Honda has a pretty good reputation for figuring stuff like this out.

Lightening the load sounds like be the "Best Option" here then. I have both the LED H4 Bulb and LED Driving Lights. The current draw is far less than the stock incandescent H4 55/60 Watt bulb. Some one might want to consider this conversion as an option, if they have any concerns regarding the subject.

A 12 Volt air compressor draws far more than the headlight does for sure.

 

[itlives]

Lightening the load sounds like be the "Best Option" here then. I have both the LED H4 Bulb and LED Driving Lights. The current draw is far less than the stock incandescent H4 55/60 Watt bulb. Some one might want to consider this conversion as an option, if they have any concerns regarding the subject.

A 12 Volt air compressor draws far more than the headlight does for sure.

Do you remember the stock number on that headlight you have? I went to the site - there's more choices than a simpleton (like me) needs. Am I right in thinking that you only have one brightness on these ? Or, do they have hi/lo beams?
Thanks for the link BTW!

 

[casualmatt]

Would the simplest answer be to wire in a on/off toggle switch to the negative wire coming from your headlamp? That would cut off both high and low beams in theory. I haven't looked at the wiring schematics for the NC so not sure. Also it would be a manual toggle, not an automatic system as you described.

 

[Brillot2000]

Do you remember the stock number on that headlight you have? I went to the site - there's more choices than a simpleton (like me) needs. Am I right in thinking that you only have one brightness on these ? Or, do they have hi/lo beams?
Thanks for the link BTW!

I bought mine off of eBay and the vendor offered me different unit because he was out of stock of the one that I placed the order for. The unit that he send was much better than the one in the eBay listing. Therefore I do not have a stock number to share with you all.

Yes, there's both a "Low & High Beam". No worries regarding that...

The website has the same unit that I got, based on the images and the light temperature (5,000° Kelvin). Refer to the Light Temperature Chart.

Visit this webpage Headlights LED Bulbs | Autolumination and scroll down about half-way to the bottom of the page until you see what's shown in the image below. This units light temperature is 6,000°, which is more desirable in my option. You will need to select either "H4 or 9003" for the bulb type.

 

[itlives]

Thanks Brilliant2000!

 

[Brillot2000]

Thanks Brilliant2000!

THX!!!

There is some work required with the installation though, such as removing all the plastic. This is a "MUST" if you want to have a proper installation. The "GOOD NEWS" is that LEDs are "Maintenance Free" and will virtually "LAST FOREVER". The inventment of the time to due a proper installation is well placed. I receommend using cable ties to secure the ballast and all the cables for LED Bulb Assembly.

Here's my album of the installation, Brillot2000 LED H4 Bulbs Installation. Do not be discouraged, it will be "Totally Worth It". Many people threat about taking off all the plastic to do any work on the bike. All can I say is that those people are "Wimps and Cry Babies"...

 

[itlives]

Many people threat about taking off all the plastic to do any work on the bike. All can I say is that those people are "Wimps and Cry Babies"...

I'm the kind that looks for a reason to take stuff apart. With my NC, I did wait until the shop manual came in. I don't like breaking plastic! The fake air scoop is ridiculously easy to get off!

 

[BerndM]

Would the simplest answer be to wire in a on/off toggle switch to the negative wire coming from your headlamp? That would cut off both high and low beams in theory. I haven't looked at the wiring schematics for the NC so not sure. Also it would be a manual toggle, not an automatic system as you described.

I did actually consider that but I don't want to do that because I would probably forget to turn it back on, in the daytime, and end up with a ticket.
Another reason for thinking about a relay is that there are times when you want to do something to the bike that requires the key to be on, but engine NOT running. In that situation, having the silly headlight on would be a major negative.

 

[Brillot2000]

I did actually consider that but I don't want to do that because I would probably forget to turn it back on, in the daytime, and end up with a ticket.
Another reason for thinking about a relay is that there are times when you want to do something to the bike that requires the key to be on, but engine NOT running. In that situation, having the silly headlight on would be a major negative.

I found a solution last night after reveiwing the wiring diagrams.

In a "Nutshell" here's the run down:

Install a relay to break the connection to the headlight supply wire to the left switch assembly when the starter button is "Pressed". It would have to be accomplished by installing a relay using the Common Contact (30) and "Normally Closed" (N.C. - 87a) contact between the "Blue/White" wire from the fuse box to the Headlight Selector Switch.





The coil of the relay (86) would have to connected to the "Yellow/Red" wire leading to the start solenoid and then to ground (85). This would insure that the headlight is "OFF" when the starter button is "Pressed" and Headlight selector switch is in either position.

However implimenting it might a little tricky though. Please standby...

 

[670cc]

I found a solution last night after reveiwing the wiring diagrams.

In a "Nutshell" here's the run down:

Install a relay to break the connection to the headlight supply wire to the left switch assembly when the starter button is "Pressed". It would have to be accomplished by installing a relay using the Common Contact (30) and "Normally Closed" (N.C. - 87a) contact between the "Blue/White" wire from the fuse box to the Headlight Selector Switch.

View attachment 19665

View attachment 19664

The coil of the relay (86) would have to connected to the "Yellow/Red" wire leading to the start solenoid and then to ground (85). This would insure that the headlight is "OFF" when the starter button is "Pressed" and Headlight selector switch is in either position.

However implimenting it might a little tricky though. Please standby...

There is a potential weakness in that plan.

You are requiring that the relay coil be energized to switch off the headlight. The battery voltage during engine starting will be lower than 12 bolts due to the load of the starter. With a healthy battery, the relay will still probably pick up and cut out the headlight. Now when the battery is weak, and you need the mod the most, what if the voltage drop is so much that the relay coil cannot pull the contacts and the headlight stays on? In the the situation that you are trying to prevent, that design may actually fail.

I'm not saying this idea has no merit, but here is my thinking. After years go by my battery gets weak. One day my starter cranks too slow and it won't start the engine. I reach inside the fairing and pull off the headlight connector. Maybe that gets it started one more time. Then I go but a new battery ASAP. Now I'm good for 6-8 more years.

 

[showkey]

Ok.......fun engineering exercise..........BUT..........

Why are we looking for a solution to problem.........when there is no problem.
The NC has plenty of excess power to handle heated grips, heated clothing, GPS, radio, cell phones and small aux lights.

Adding any switches, relays or any thing else just adds complexity with little or no value.
Even the headlight LED bulbs can cause issues because the headlight lens reflector demands the bulb filament to be a precise location..........some LED bulbs do not provide that location or precision.

Any device that could cause the headlight to go out while under way or makes the rider take some action to turn it on is a bad idea. There was a reason for the regulation outlawing headlight on/off switches in the US.

 

[Brillot2000]

There is a potential weakness in that plan.

You are requiring that the relay coil be energized to switch off the headlight. The battery voltage during engine starting will be lower than 12 bolts due to the load of the starter. With a healthy battery, the relay will still probably pick up and cut out the headlight. Now when the battery is weak, and you need the mod the most, what if the voltage drop is so much that the relay coil cannot pull the contacts and the headlight stays on? In the the situation that you are trying to prevent, that design may actually fail.

I'm not saying this idea has no merit, but here is my thinking. After years go by my battery gets weak. One day my stsrter cranks too slow and it won't start the engine. I reach inside the fairing and pull off the headlight connector. Maybe that gets it started one more time. Then I go but a new battery ASAP. Now I'm good for 6-8 more years.

Someone asked for a solution and I supplied them with one. I spend about 15 minutes in finding this solution. I did not do any Validation or Reliability Testing on this concept though. If I have an annual budget of $1.2M, then we are on our way to "Kick-Off" this project then.

Your comments about battery voltage are validate ones. The battery voltage would typically drop to about 10 volts when the engine is crancking, which should be enough to keep the relay latched during the cranking of the starter motor.