Introducing the Sparck Moto FB-11

[firebane]

So its essentially a motogadget M-unit?

While simliar its not.

These guys have added things like relays. In case you didn't know when you run your headlights off a bikes strandard electrical system then can draw a lot of juice making it difficult for other components to work.

By adding a relay things like headlights won't draw as much off the main system any more.

[Tim]

Not to be argumentative, but I don't think relays can reduce the load of any particular light or horn or what have you.

They direct power to the fixture from the battery via the relay, keeping the amperage out of the switch, extending the life of your switch and reducing the gauge wires etc. you need in the switch.  This is how heated grips work, my high-draw Stebel horn, the starter motor on your bike (the solenoid is just a giant relay) etc.

Somehow magically I think the M-Unit can allow control of multiple things from a single switch or something like that.

Anyhow - I'm going to be signing up for one of the Sparck Moto units and wiring harness for my SR500 project I think!

[Sonreir]

The benefit of the relay is that it reduces the distance the current has to travel to activate the device.  As you may or may not know, longer wiring runs introduce additional resistance and more resistance means less amps.  Switches also add extra resistance, too.

By using a relay, you can feed power directly to the high current devices from the battery.  Lower resistance means more amps and so your headlight may be brighter, your horn may be louder, and your coils may have a fatter Sparck™. 

[Keiff Hardcore]

so if im getting this correctly you could have the entire harness centralized to the board?

I HIGHLY recommend you have an initial run as a group buy here on DTT. you can have a set number of units made right away and also lower costs for the group buy participants.

I have participated in SEVERAL group buys on other forums, and always liked the idea, as many people want the same product, and are much more willing to jump on board if they save $10-20 off retail on an item.

[Mydlyfkryzis]

If my CB360 had more than 1 spare watt, I'd consider it for that. But that board is exactly what my NH750 needs.  Between running likes, air horn, Lights on my panniers, I have a mess of extra wire. Been looking at the third party stuff, but never quite the right mix.

This looks like a better, more flexible arrangement. 

If it is half as good as your Reg/Rect than I will be waiting for the release.

[Tim]

Well I knew the length of the wire makes a difference, but I didn't think it would make that much of a difference on these short runs.  But I suppose every watt counts!

[Sonreir]

The switches have a much greater impact than the wires, in practice, but it all adds up.

Lets say you're running a headlight with a high beam resistance of 3.5Ω...  At 14V that works out to 4A, or 56W.

Same headlight, but now we add only .7Ω for resistance of wire and switches.  Our voltage regulator is still keeping us at a steady 14V, so when resistance increases, it's Amps and Wattage that drops.

I = V / R.

Down to 3.3A now and that puts us close to 47W.  Lost 10W due to resistance.

And I don't think that .7Ω number is unrealistic for a standard setup, either.  I just measured a few wires, connections, and switches.  The switches I have in stock are adding about .2Ω per switch and each crimped connection is adding about .03Ω.  When you consider that most stock setups take the flow of current through the ignition switch, fusebox (twice), and several connectors, a straight shot from a relay is looking better and better.

[eyhonda]

Nice intro, Matt!  Much cost savings can be realized by not populating the full board.   As an idea, you can offer different levels/versions off the same PCB.   If you only want one switched relay circuit, offer a version without the other two relays and fuse sockets inserted.   As a correction, there are five ground taps not four (unless one is used for the off board relay).    Some of the smaller singles may only need a fourth of the capability.   Granted it will still be the same size for a base version, but the price can be lower.   Maybe set up 3 or 4 levels of build, based on the number of switched relays.    But at first we really need to beta test these parts to check current handling and overall reliability.   The components are already automotive spec'd.   It is the board that I designed that needs to be field tested before production release.    It sounds like we have a few willing testers though!

Edit:
Just to add to Matt's response on current draw and voltage drops.   The worst voltage drops/high resistance points are those old bullet connectors.   Any place with a loose connector will have a big resistance that increases voltage drop with current.  Off the top of my head, the on board relays have a 150 ohm coil that only draws 80 ma thru your switch.   If your battery is at 14 v, add up all the voltage drops and you are likely to be in the 11 volt range to your headlight.  With a relay circuit, it will drop much much less.

[Sonreir]

As a correction, there are five ground taps not four (unless one is used for the off board relay).

Counting is hard... 

[Keiff Hardcore]

yes, all those little bastards add up.

i honestly dont get why there are so many dedicated grounds on bikes. it seams wasteful.

oh and it would be realy cool if you did a DIY kit that included wiring and maybe a few other bits so the entire conversion could be done with one purchase.