Bottomfeeder

I was wondering if anyone has tried one of the new LED substitutes for their MR16 series halogen bulbs in their DIY bike lights. Some of them are interesting - featuring up to 3 3 watt emitters. Of course they are more expensive than the halogens. But if they put out enough light, the burn times should be WAY longer for a given battery. Any real world experience with these?

DanO

ovrrdrive

Sounds interesting... Where did you see those?

Giro

I only got one response to a thread I posted a while back. Links for some of the sources still valid:
LED Liquidators
SuperBrightLEDs
Some also show up on eBay. Try searching LED MR16.

Not quite as high an output as the original poster mentions and heat could be a problem for the LED's themselves.

Just found another possibility at EliteLED.com at LINK
LED Type: CREE XLamp XR-E LED (3 pcs)
Bubl Base: MR16
Life time: 20,000 Hours
Color: White (6000K)
View Angle: 15 Deg
Light output: 240 Lumens
Operating Voltage: 12 V AC / DC
Power Consumption: 3.6 Watt
Product Diameter: 1.96" or 50 mm
Product Length: 1.9" or 48 mm

ovrrdrive

Wow, 240 lumens at 3.6 watts...

I see a bank of 3 or 4 of them being a definite possibility and using the same power consumption as a 20 watter. Phillips lists their halogen MR16 as having 240 lumens also. I bet the perceived difference in output is due to the difference in color of light.

I'm definitely going to pursue this option once I get a good battery solution. Though of course, at $35 each I'll have to be selective. Ouch.

Bottomfeeder

One thing I did notice while reading some of these links is that there is a 14 volt limit. So they may not tolerate over-volting as well as the halogens. That in itself might be a deal breaker for me, since I just dropped a C-note on a 14.4 volt battery and charger.

DanO

jeff-o

That data must be incorrect. Those emitters draw about 700-800mA each at 3.5V. I assume they're connected in series to run from 12V, so that's about 9 watts. I'm also puzzled by the output, three XR-Es should produce more than 240 lumens together...

skingry

They are only running at ~1W each. The bulbs aren't that great. I bought one and was unimpressed (from a cycling standpoint).

If I were using the bulbs for product display, they'd be ok.

ovrrdrive

I noticed the same thing too. Looks like a buck or puck thing will be needed to run these off of a strong 14.4V battery setup. At $35 each for the lights the buck will be the cheap part.




You bought one of the ones using the 3 XRE's and was unimpressed or just one using 3 LED's?

It stands to reason that the one using the XR-E bulbs would be fairly bright, but real world always speaks louder that specs.

jeff-o

Ah, well that would explain it. Why would they under-power it??? Heat issues?

kk4df

A simple 7812 voltage regulator (plus 2 small capacitors and a heat sink) would do fine with your 14.4 volt battery (max 12 watts output). I use a 7805 5-volt regulator to recharge my Garmin 305 from my 14.4 volt battery.

Bottomfeeder

I figured there existed circuitry which would interface between the 14.4 volt battery and the 12 volt bulb... Then again, I'm pattin' myself on the back for managing to solder a halogen bulb socket to a manufacturer supplied lead off the battery.

DanO

Cody Broken

Please help the electronically impaired understand:
So this an LED substitution/upgrade to MR-16 halogen light?
You pull out the halogen bulb and reflector and install the LED in its place?
You retain your housing and mounting set-up?
And you get longer run-times and you are happy?

side note: skingry, I enjoy your avatar. I know it's not in the dictionary, but "Asshat" is one of my all-time favorite words.

Portis

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skingry

Probably not the XR-E's, as I bought it a year ago. I think mine has Luxeon LED's.

Still, there isn't enough metal to properly wick away the heat generated by the XR-E running full bore (700mA or 1000mA). Running at 350mA puts each of the LED's at ~100lm for cool white, so the 240lm rating is about spot on (making each LED running at about 1W). Not bad for three watts... but doing the math:

80 Lumens/Watt
6 Lumens/Dollar (assuming the bulb is $40 shipped... remember this is just for the bulb, to get a truely accurate figure you would have to factor in the cost of a battery and charger)

You would stand to have a much more efficient system from an overvolted halogen (both in lm/W and lm/$).

ovrrdrive

The price is definitely a drawback for sure...

By the time you get a decent battery, mounts holders and wires, fixture and lamp you'll have just about as much in it as a store bought 200lm light.

But then of course comes the ability to add another lamp and double the lumens later on...