Stock lights receive 12v DC or 12v AC current?

[Guest Andy G]

Hello Everyone!

This topic has been driving me crazy!  The local Yamaha dealer parts department says that the Banshees already have a rectifier to transform the voltage from 12v AC to 12v DC - which means that the stock headlights are fed 12v DC.  

But then I see multiple articles stating that the lights receive 12v AC.  Which one is it?  AC or DC?  

I purchased an LED bar (72watt / 12 inch) and need to determine if I need to add a rectifier before the lights to convert 12v AC to 12v DC???  
Or if I simply can plug and play w/o any conversion (if stock wiring does in fact provide 12v DC).  

Anyone have proof?  Even experiences with LED installation on banshees would be helpful & appreciated.  

Thanks in advance!

 

 

[hoppedupandcutdown]

12V AC current, but use DC bulbs, and is tested with DC volt meter. NO RECTIFIER.

 

[hoppedupandcutdown]

You can wire in your LED bar, some last, some do not. Best to use a rectifier, even better to do a dc conversion and run a battery.

[Guest Andy G]

Thanks for your reply.  

Just so that I have both your replies clear...

1) If you simply replace the bulbs, use DC bulbs and it will work.  No rectifier needed.  

2) If I install the LED bar, then I SHOULD use an LED rectifier

is that correct?  

If yes, then aren't LEDs designed to use DC voltage.  So wouldn't #1 above essentially be the same use case as #2 above?  Both needing rectifiers (because both would be using LEDs).  Or am I missing something?  

Also, any input on what the parts individual at my local Yamaha dealer was referring to when he said "the banshee has a regulator that also has a rectifier"? 

Thanks!

 

 

[hoppedupandcutdown]

They come with DC bulbs, they (the bulbs) don't care that the current feeding them is alternating.

[hoppedupandcutdown]

The Banshee has a 1 wire regulator, nothing close to a rectifier.

[hoppedupandcutdown]

The Banshee puts out AC voltage. The LED bar wired direct will turn off and on a bazillion times a second without a rectifier converting it to DC. Some light bars last for people, some do not.

[Keno]

Regular bulbs use a resistive tungsten wire that heats and glows. The resistive tungsten wire doesn't care which way the electrons flow and glows either way. ALL resistive filament bulbs can be used with AC or DC. Including house incandescent bulbs

 

LED stands for Light Emitting Diode. Diodes only allow current through in one direction. Without a rectifier or full wave diode bridge to the LED bar you are blocking half the AC wave form causing increased flicker, dimming, and possible death of the light due to every trough of the wave form being like hooking the light up to reverse polarity. (Most likely kill the input capacitors or led controller chip)

 

 

[Guest Andy G]

You guys are awesome!  I'm glad I posted this question on bansheehq.

My 12" light bar is 72 watts.  Which means that if I need to convert 12v ac to 12v dc using a rectifier, I'll need a rectifier to support a minimum of 6 amps (72 watts / 12 volts = 6 amps).  

I picked up a 100v / 8amp rectifier for $1 at a local electronics shop.  This should work for what I need.  

I watched a youtube video where the guy indicated that when you rectify 12v ac, it actually output about 17v DC (which is fine, because the light bar supports 10 - 30 volts DC).  Even with 17v DC, I only fall at 4.2AMPs (72 watts / 17 volts = 4.2 amps).  

Attached is a pic of the rectifier.  

Sound about right?  

 

 

[Keno]

That's what you need! Yeah, the peak will be around 17v DC but the average voltage will be 10-11v DC. You'll still have a little flicker at idle, but won't be as bad. If it bothers you, put about a 2200uF or larger 25v capacitor across the positive and negative of the light.

 

edit: should be 22,000uF and can actually be a little smaller.

 

 

[Guest Andy G]

Awesome!  That was going to be my next question (capacitor).  What equation was needed to determine the size of the capacitor - so that I know how u came up with 2200uf or larger 25v?

[Keno]

Well, actually I messed up. Forgot a 0.  Should be 22,000uF capacitor.  So max voltage is roughly 17v so add in a safety margin say 40-50% so 17*1.45=24.65v. This is the lowest voltage rated cap you should choose. Can be any voltage rating above 25.

A very rough estimation of capacitance needed is  capacitance=amperage/(frequency*voltage drop)

So a Banshee idles at about 1500 RPM. And Hertz is cycles per second. So a Banshee idles at 1500/60=25hz.  This is also the time it takes for the flywheel to complete 1 revolution meaning our AC Frequency at idle is 25hz (0 to 12v to 0 to -12 to 0).  Since we are putting the waveform through a Full Wave Rectifier the cycle frequency doubles. So after rectification we have a Frequency of 50 HZ due to the negative portion of the AC signal being flipped to the positive side.

I chose an arbitrary number of 5v voltage drop as 17-12=5

capacitance=5a/(50*5)=0.02F or 20,000uF

I went to mouser and looked for a cheap Capacitor and there Were some 25v 22,000uF caps for less than $4 so Decided that would work.

You can probably get by with a much smaller cap, as the light bar has its own capacitor built in and this formula isn't super accurate.

[Guest Andy G]

This world needs more people like you! You guys are freaking awesome!

[Guest Andy G]

Thought I'd provide an update with my results...  

I tried the capacitor at 22,000uF (25V), but it dims the light down to about 5%.  Almost to an OFF position.  Looks like 22,000uF is a bit too big.  

I installed a capacitor with 6,800uF (25V) and it brightens the lighting just a pinch during a low idle, so it cleans it up a bit.  

For those out there interested in what I paid:  

12" LED 72watt light 5D style lenses = $26 - Amazon (prime shipping)

DIY bracket - just a couple piece of square piping at 3" with some grinding = FREE

100v / 8A rectifier = $1 - local electronics shop

25V / 6,800uF capacitor = $5 - local electronics shop

Outdoor IP66 casing to hide wiring connections & rectifier = $6 - Amazon (prime shipping)

Total = $38 (installed myself)

 

 

 

[Keno]

Good to know you got it sorted out.  There must not be enough current at idle to charge the cap and run the light at idle.  BTW I did some testing on my "72w" light bar and it is actually a 25w FWIW.  So yah, 6800uf should be more than enough.