Article [13] ST1300 - Spoiler fitting

jfheath

John Heath
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This isn't a new idea and has been mentioned before in these forums. But when I needed it, I couldn't find what I was looking for in one place.

A (very expensive) addition to the Honda top box is the colour matched spoiler. It comes complete with a row of high intensity Red LEDs which are plumbed into the brake light circuit. High level brake lights are now a legal requirement for all new cars in the UK. They are a pretty good idea on the ST1300 too.

However, if you have ever followed another ST1300 in poor daylight, you soon realise how poor the rear lights are. This little modification converts the LED brake lights into a tail/stop light. It requires a few electronic components - 2 diodes (or rectifiers) and a resisitor, some wire and (optional) a couple of electrical connectors.

The idea is to feed the LEDs with two power inputs. One from the brake light circuit, another from the tail light circuit, but at a reduced voltage. The diodes are there to prevent the power from the brake light circuit flowing into the tail light circuit and vice versa.

It took a little experimenting to get a resistor of the right value. The tail light mustn't be too bright, or it won't be possible to tell when the brake light comes on. Too dim, and there is no point in having it !


Split View.jpg


A split image showing - left side showing the tail light, right side showing the brake light.


Tail Stop Diagram.jpg


Circuit diagram The 3 wires from the left are tapped into the 3 leads going to the tail stop light.
Green = Earth
Brown = Tail Light
Yellow / Green = Brake light

Please check the colours of the leads to your tail light rather than relying on the ones shown here.

The two wires on the right go to the LED brake light.



The two diodes are 1N5400 - more than big enough for the job
The resistor is 220 ohm, 7 watts. Again, I've gone for overkill.


Components.jpg


The photo above shows the components laid out on the circuit diagram.


Diode.jpg


The second photo of the diode shows the orientation - that grey stripe at the end is in the same location as indicated by the black bar on the diagram - in this case pointing to the right.


Note the white connector on the right is designed to fir into the connector provided with the Honda spoiler. Check that the colours of the wires match before connecting together.
The green connector on the left is optional. There is nothing to plug it into unless you put the female part in place yourself. The alternative is to hard wire it in place. I prefer to have connectors - it makes it easier to replace the module if necessary. In fact, in the event of failure, I have a simple lead which connects the green connector to the white to reinstate the LED as a standard brake light.

Wiring.jpg

A shot showing how I wired this up. The size of the resistor in its hard rectangular ceramic case makes a sturdy device to which the diodes can be secured. The diodes were taped to the resistor and the ensemble was then put into a length of 3.5cm wide heat shrink tubing and effectively shrink-wrapped - leaving two wires at one end, 3 wires at the other. This does not show green earth wire which simply passes from one side to the other. Neither does it show the connectors.

I didn't have the correct colour wire at hand. The orange lead is the one from the +ve tail light circuit (brown on the diagram). The yellow lead is the one from the +ve brake light circuit (yellow / green on the diagram). That dark grey looking lead on the right alongside the yellow is actually a shadow from the flash !



To get at the wiring for the tail stop light, remove the rear mudflap - 4 bolts. The rear light holders can be removed (best to undo both sides. The right lamp holder is connected to the wiring loom, the left is connected to the right. I found that there was more wiring to play with on the right hand bulb holder. Best to remove the bulbs (don't touch with fingers), otherwise you risk breaking them and kneeling on the broken glass. If you decide to cut and crimp on new connectors, make sure you have enough length of wire to operate the crimp pliers. You might need to work closer to the bulb holder than you would prefer.

NB - Make absolutely certain that you have the diodes facing in the correct direction - that grey band must face in the direction of the LED wire. Also make certain that the connector wires are in their correct place.

In the UK, Hitachi connectors can be found at SG Motorsports.
In USA this is one supplier mentioned in a different post http://www.electricalconnection.com/
Diodes and resistors bought over the internet from Maplins (UK)
 

sky.high

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Hey John, cannot seem to find 7w 220 ohm resistors on Aliexpress, 5w or 10w are available which one should I buy?
 

jfheath

John Heath
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I doubt that it really matters - but I never found out how much current the LED lights actually used. Probably much less than couple of 5w tail lamps - but since I didn't know I went for 7w. Again, unnecessarily erring on the safe side, I'd fit the 10w if I was doing this again and 5w and 10w were my only options, even though my suspicion is that it would use much less power than that.

So 5w is probably ok. 10w is definitely ok (because mine has been OK for years with a 7w resisitor ! The figure for the wattage of a resistor is an indication of the maximum power that the resistor can have passing through it. It needs to be a high enough to cope with the power - otherwise bits of it melt ! It's not like a headlight bulb where the wattage represents the amount of power that the bulb consumes.

220 ohms was the best compromise for me for getting a bright enough tail light, but dim enough for the brake light to be significantly brighter.

But that way (10w) you know that it can handle whatever power the tail light requires without the risk of overheating. The larger ceramic block gives a much more solid structure to support the wiring and diodes. Its important that those joints cannot move relative to each other. I used heat shrink tubing, but strapping it with tape to the body of the resistor will do the same job.
 
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sky.high

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Thanks again John, 10w it is, only a couple of months now before Aliexpress delivers and I can report back with results LOL
 

ST Gui

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I already have a abundance of brake light then I guess you can never have enough brake light!
+1 The thing about most motorcycles is the brake lights and tail lights share the same lens/lenes so the difference is the level of brightness. Those lenses are often lower than the following driver's line of sight or concentration.

After the development of the CyberLight and SF's trial of center high-mounted stop lights on taxis DOT required the CHMSL on passenger vehicles. That light was a dedicated brake light not a tail light aka running light. The mounting position and brake light only function as been shown to reduce rear-end collisions. Not guarantee they won't happen but a move to reduce them.

I've always wanted a Honda top box and only because of that slick spoiler LED. Going from dark to brakelight-bright has an edge IMNSHO over a tail light brake light combo. So if you chose to combine the functions on the LED you'll want to ensure there's adequate difference in brightness so that it not only acts as a brakelight but looks like one too.

Once you get it wired up as a combo you could add an LED flasher that flashes the brakelight momentarily then keeps it on steadily.

[edit] Ok I somehow completely missed John's that cover all the salient points and then some.
 
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jfheath

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That is an interesting and important perspective @ST Gui .

When I bought the spoiler, I wanted it primarily as a better rear light. I reckoned that the normal stop lights were bright enough, but having ridden behind many other ST1300s the tail light might as well not be on in some low light daytime conditions. Like car sidelights in fog. You see the car before you see the lights.

But those LEDs are very bright and would dazzle and distract if they were used unresisted as an extra tail light rather than a brake light.

I experimented with combinations of 100, 220, 370 resistors - I bought 2 of each and wired in various series / parallel combinations and checked in daylight from the end of the drive with the bike in the dark garage, and with the bike out in the daylight. Long bit of string on the front brake lever. Just visual assessment using the Goldilocks sample and eliminate process. Too bright, too dim, just right.

Then the ultimate scientific test of someone riding behind me and passing comment. "Yes, that'll do."

The Diode does drop the raw brightness of the stop light, you notice it if you have seen it operate as intended as just a brake light. But but it is plenty good enough even with the diodes 0.7v drop.

I did consider a relay circuit to get the full voltage through, but when I saw how effective it was with the diode / resistor solution, it simply wasn't worth the hassle.

My first attempt was with lower quality resistors that looked similar to the diodes. The resistors didn't fail or burn out, but it was impossible to join them together in a way that was robust. The wires broke off where they met the diode or resistor casing. That large ceramic rectangular block keeps everything nicely strapped together and has been on this bike for over 50,000 miles. I did make a spare but have never needed it.
 
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Andrew Shadow

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I've always wanted a Honda top box and only because of that slick spoiler LED. Going from dark to brakelight-bright has an edge IMNSHO over a tail light brake light combo.
Installing the below top case allowed me to solve both the issue of being more noticeable and having an extra dedictaed brake light, as well as giving me me a place to store my helmet.

There are three sets of LED's in this top case.
The lower level light assembly is actually a row of LED clusters. Each bright spot is actually a cluster of five small LED's. They are wired so that two LED's of each cluster illuminate when one wire is powered. The remaining three LED's of each cluster illuminate when a second wire is powered. You can connect them to 12V + in any way that you wish.

I wired them so that two LED's of each cluster are powered all the time as running lights. The other three LED's in each cluster are connected to the brake light circuit.

The top light is a dedicated LED brake light that comes on at full brightness only when the brakes are applied.
I installed a flasher unit that flashes the brake lights quickly initially, then the flashing slows to where the brake lights stay on.

This gives me a row of double LED clusters burning constantly as running lights up high on the bike. When I apply the brakes, the second row of three LED clusters and the upper dedicated brake light come on in a rapidly flashing pattern that slows to brake lights constantly burning. All of them up high and the full width of the bike. It seems to work very well. The row of running lights are not particularly noticeable during bright daylight, but I have been told that in lower light conditions and at night it is impossible not to see. I also have the Garry Rowe LED brake light mounted on the rear grab rail platform, also connected to the flasher. I have been told that the brake lights are very attention getting.

1638373174444.png
 

jfheath

John Heath
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Nice solution - and it gets around the weight limit issue. That Honda spoiler is very heavy and it then becomes part of the permitted load of the top box. Honda don't reveal what additional downforce is added by having the airflow spoiler on the back !!
 

sky.high

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Aliexpress delivered the components to wire my spoiler for both running light and brake light intensities as per @jfheath awesome detailed instructions and here's the result
Thanks John, you did it again!
 
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