• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

Aux Lighting Help

NavyCWO

New member
I have two LED lights I want to add to my '93 R100RT to increase my visibility.
I also have a stock BMW rocker switch on the panel for energizing them.

I mounted the lights on the "crash" bar and hooked them up to the coil so they would only operate when the
ignition is on so I couldn't run down the battery if I neglected to turn them off after a ride. Lights work great;
but if I turn them on when the bike is running, it dies as soon as I turn the aux lights on. I must have it hooked
up to the wrong terminal. I would appreciate any suggestions or guidence!

Thanks!
 
I'd look for a different switched circuit to use; a light circuit, perhaps the high beam. Is there a relay in the circuit? If not, then I suggest adding one as a way to control when there is power to the lites.
 
+1 on the above; but I would run the Aux lights through a relay. The switches and circuits are not designed for the high amperage that the aux lights require. One uses a light circuit for a "trigger" for the relay with the actual power to the lights from the relay coming from a heavy duty wire, fused, often directly from the battery.............
As an aside, your electrical system should be able to carry this load; but with much more, like heated clothing, etc you might want to check out boosting the output of the electrics........Rick at "motorad electric" can easily help you with both subjects.......the relay, wiring, and more power availability...........God bless........Dennis
 
Thanks guys! I'm going to use a relay to run the power. Guess I unintentionally ended up grounding
out the coil when I switched on the lights! OOPS!
 
Glad you found out.......but sorry it was the HARD way. Please make sure you "fuse" that circuit............God bless .........Dennis
 
Yes, you grounded the coil through the lights, making the ingnition (points or trigger) invisible to the coil.

If the LED's are to be on all of the time, use the parking light circuit in the headlight.

If you want them only with high beam, go to the white wire at the headlight.

If you want them only with low beam, go to the yellow wire at the headlight.

And in all three cases, put a switch between the source and the LED units for "off".
 
Paul:

I think I'll use the parking light source as I do not want to forget and leave them on when I park the bike.
I have a switch so this should work. I'll take the tank off tomorrow and play with it. Thanks!
 
FWIW
LED lights do not really require a relay unless they are one of the rare ones that draw 30W or more. Most are 10-15 W lamps meaning a pair draws about 2A. You can power direct from a battery terminal (or any circuit that will provide an extra 2A without blowing a fuse) with an inline switch without using a relay in these cases because you will not overload the switch.
LEDs also have voltage compensation so will put out full power even if voltage is a bit low, another reason a relay is not required.

Nothing wrong with using a relay if you wish- if you hook the trigger to a switched source like the parking lights it will ensure you don't leave the lights on which the battery arrangement would allow.
When using relays on bikes it is wise to use sealed ones so water doesn't kill it early. A little extra effort put into soldered and crimped connections, plus a bit of loom to protect goes a long way in ensuring long term reliability.
 
Why not investigate a Fuzeblock for adding additional electrical farkles? Very easy to install, can add up to six circuits and you select whether a particular add-on is on all the time or switched. Has a built-in 30amp relay, and comes with an assortment of fuses. That way, only one thing needs to be wired directly to the battery (the Fuzeblock). Battery terminal bolts are only so long, and you soon run out of room to add more connectors, and you risk having your battery connection become loose, and theres not a lot of clearance even if you can add longer bolts. Add-ons can add up quickly between lights, heated clothing, heated seats or grips, extra power plugs for GPS or smartphone hookups and charging, and you can wire a battery tender pigtail right to the Fuzeblock.
 
CWO, you've been provided some good info here, but it is a bit like the guy who asks the time and we tell him how to build a watch.
 
Back
Top