Investigating 15£ auxiliary lights & calling electrics gurus

[Lemonwizard]

I figured since these were so cheap and from wish (notorious lack of quality control) checking out what's inside might be a good idea and potentially interesting.

I haven't tested the illumination itself yet, only looked at the components. Material seems decent and sturdy enough to withstand a low speed crash, but you can tell that these are cheaply made; the threads by which the compartments are held together are very rough and the black paint is chipped in some places. I guess this doesn't matter though as long as the LEDs work and no wires are burning up.

Here my questions for the gurus:

• Is a relay necessary? If I understood it correctly, the relay controls the main circuit (battery>switch>lights) via a small circuit that gets its power from a switched source. Are there any drawbacks to not using a relay other than my battery being sucked dry if I forgot to turn off the lights or if someone thought it would be a swell idea to fiddle around with the buttons on a parked motorcycle?
• Each light has a wattage of 15W. (2x15)/12 = 2.5 Ampere. What fuse should I get for this? 3 Amps? 4? 5?
• I read somewhere that it's important to not skimp on the wire size (diameter) for safety reasons and also because you will potentially end up with a brighter light if you use a bigger wire as more current can flow through it. The wires coming from the lights (about 40cm in length) are very thin as you can see. I can't completely replace these wires as they're glued to the board, but would it be beneficial to shorten them as much as possible so that the thicker wire is closer to the lights? The splice would be inside the plastic casing of the lights, so waterproof and instead of 40 cm (16 in) of thin wire there'd only be 2 cm. (barely 1 in)
• Lastly, the switch doesn't look waterproof at all. Does anyone here have a switch like this in use? Any good or bad experiences?

Thanks 

[Rixington43]

- A relay isn't 'needed', plenty of people attach lights, heated grips, heated clothing etc directly to the battery. It's only the risk of leaving them on or some helpful person turning them on whilst you're away from the bike (These days I do find it prudent to cater for the existence of truly awful human beings though sadly). Adding a switched relay with multiple outputs might make adding more accessories in future easier though if you think you might want to do that.
- 3 Amp should be fine, 0.5A on 2.5A is considerable headroom in % terms.
- I would leave the wire as it is, my GCSE electronics is a little hazy but whatever the thinnest wire is in the system will always be the bottleneck and so shortening it will just concentrate the bottleneck, think filament in a light bulb.
- Can't comment on the switch I'm afraid as mine is quite different.

[UK_Vstrom650]

I have the same switch and have used it in all weather for years without any issues. I tend just to leave them on all the time, but on the few occasions I have turned them off the switch has worked fine turning them back on. Just make sure you angle the lights down so you don't blind oncoming drivers.

I use a switched relay and definitely recommend it rather than wiring to the battery, as it adds the extra protection against leaving on/someone fiddling with it.

[kwackboy]

Personally I wouldn't use a relay, they're only 15w.
Wiring them directly to an ignition live with an in-line fuse, this will be safe enough and you won't forget to turn them off ... ! 

 

[Lemonwizard]

No relay, no potential battery vampirism and even safe? Lovely.

What kind of method would you recommend for tapping into the ignition live?
And is there any particular circuit that might be best suited for this?

[kwackboy]

The Brake light circuit  ... 

Tap into the live side , Orange wire I think ?

[SimonW]

Buy something like this and you don't need to chop the cable (not sure if this is the right connector or not, but it looks pretty close).

[kwackboy]

Sorry I should have mentioned that the rear brake switch is easiest, the plug is under your tank mount, in front of your battery and the connector should be two wire and white in colour.   

[Keith60]

If God says he wouldn’t use a relay, I wouldn’t!  God has spoken!!!   OK it’s Kwackboy, but when it comes to bikes he’s the next best thing!!!

[Lemonwizard]

My thoughts exactly

            

[UK_Vstrom650]

Whilst you don't need a relay, using something like Bigpie's excellent aux relay kit means you have a switched connection & room to add additional electrical accessories as plug and play items.

[Lemonwizard]

Figured I'd give an update since I like thorough threads.
I suppose these aux lights can be summed up with the proverb "you get what you pay for".

Pros:

• very cheap (even including costs for additional items needed for proper installation)
• looks adventure-y

Cons:

• depending on your crash bar's shape you might have to buy additional mounting brackets (I had to)
• the wiring can be easy and fast, but if you want it done nice and proper you'll have to tinker around a lot and buy addition items like a relay, shrinking tube, fuse...
• the lights and metal cages are sturdy enough, but compared to more expensive sets actually rather flimsy
• very prone to rust (not on the inside though I hope)
• the switch is of pretty low quality. I've barely used the lights yet, but the switch already has some sort of loose connection resulting in unsynchronised left and right lights
• the luminosity is alright, not very bright but certainly a good addition. I suppose an optimist would list this as a pro.

Conclusion:
If you're all about that adv look, these cheap lights will do the job. They'll also provide some extra visibility at night.

However, I think high quality and more expensive aux lights are a much better choice.
Easier installation (possibly even plug-and-play), looks even better, less to no rust, much brighter, probably no headaches later down the line, customer support... 9 times more expensive but worth it!