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Motorcycle headlights

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Spider Tu Sefen

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Hi spec - as it happens I have just purchased a motorbike 2nd hand - a Husqvarna WR300 (enduro bike with factory lights/indicators but no starter motor or battery) ; and i want to add a rectifier to run a (new) LED headlight, and LED park light and also i want to add a USB charger for my GPS to run the bike in the desert where it cooler at night. Looking at the schematic where do you suggest to best add 1 or more rectifiers to provide DC for these 3 items. The bike has to be kick started/running outdoors (noisy +smoke) for electrics to function as it has no battery. It took me a while to realise this bike had lights functioning on AC (makes sense now i know but not what all my previous 9 motorbikes had) - :( only after i blew the first USB - then i searched further and found the WR300 schematic below) - i had already put in a temporary LED headlight and LED park light bulb - they worked fine (less amps) but not sure how long they will run on AC?



(from the above) Is the Yellow wire "Y" outputting DC into the dashboard as is? might be enough for USB 1 amp (edit - i don't think it is as the dashboard probably has a built-in rectifier)
Where is the best place to splice in a rectifier for headlight beam/dip/park? thanks ....
 
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cowboybob

Well-Known Member
Most Helpful Member
Welcome to ETO, Spider Tu Sefen.
... It took me a while to realise lights it was AC - :( after i blew the first USB - then i searched further and found the schematic) - i put in a temporary LED headlight and LED park light bulb - they work fine (less amps) but not sure how long they will run on AC?...
It would appear that the Yellow wire, that feeds the lights, is DC, As evidenced by:
... i put in a temporary LED headlight and LED park light bulb - they work fine (less amps)... .
Yet:
... but not sure how long they will run on AC? ..
They wont.

So, thus far, I see no need for the modification (extra rectifer ckt).
 

crutschow

Well-Known Member
Most Helpful Member
It would appear that the Yellow wire, that feeds the lights, is DC, As evidenced by:
i put in a temporary LED headlight and LED park light bulb - they work fine
A LED will work on AC since it acts as a rectifier, but the reverse voltage rating is likely being stressed.
If you add a 5A Schottky diode is series with the each LED it will prevent the reverse voltage from damaging it.

A multimeter measurement can determine whether the voltage is AC or DC.

You could add a bridge rectifier and capacitor filter to provide power for your GPS.
Be aware that you can't ground the output of the bridge as that will short it, so both the positive and negative output must float (not connected to chassis).
Be sure and measure the output voltage of the bridge to make sure it's not too high.
If so may need to add a 12V regulator, such as a 7812.
 
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Spider Tu Sefen

New Member
whilst waiting for the 5 amp diodes to arrive - i used 4 x 1 amp diodes and a 3300uF 25v cap i had lying around - to build an inline (on the wires) rectifier. Works extremely well - instead of the park LED pulsing and blinking badly at idle (10.2v) the parking LED is now steady and solid at idle and all RPM's - so WR300 AC front headlight system and USB charger is on it's way to being defeated and turned to DC. haha - cheap and easy
 
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