Modding My Lawnmower Headlights to two XM-Ls (& misc info)

I would like to replace the headlights on my small lawn tractor with 2 XM-L's. I'm not sure which way to go for parts - ready made drop-in or a complete D.I.Y. build. I want really floody light (I have no need to spot things out at 1000' while riding my mower!). I have thought about using two CPU heatsinks (I have access to many used/spare PC parts) and mounting the emitted to the flat end (where the CPU would have been) and then somehow mount the driver. This idea really doesn't enclose things much. I then don't know which driver would be well suited to give me 2.5A to 3A out from a a 12v input (which I guess can range from 11.8v up to 14.4v?). For hookup, I was just going to use the existing headlight leads, but add a momentary switch on the dashboard to select modes. I'd prefer 2 modes - low & high, but single or the typical Chinese 5 modes would be ok. Of course I'd like to keep this budget too!

Any ideas? Any ready made drop-in I could utilize? This 3 XM-L at DX is very pricey and seems to have heat issues. It doesn't seem floody either. Perhaps if I did use it I'd just mount one module in the center of my headlight lens (the current lens goes across the entire front end). This drop-in is rated up to 22v input.

What about using those 12v XM-L emitters found at GoodLuckBuy? Can I wire these direct drive? How much current would they drive at in direct drive? Would I risk burning them out with too much current? Do I need a resistor in-line? What size resistor?

Mower front looks like this:

Thanks for the help.


I ordered a set of LED backup bulbs from DX and installed on my mower. They aren’t really any brighter, but they are a much cooler tint than the incan so at least they look brighter. I’ve thought about using P60 drop-ins on PC heatsinks like you are thinking, and then wiring the emitters with a generic 18V drop-in, but have never pursued it. I’m curious on how you plan to do this…

I use these with a resistor to have two mode lighting on my solar hog lights. Or you could use a pot instead of a resistor for unlimited control. These are heavy duty controllers. Ledsupply can answer any question just call or email. Their customer service is the best.

These are sealed and bullet proof. I wouldn’t waste my time with a jinky modded flashlight controller for outside/outdoor use.

You definitively DON’T want to use them in direct-drive, and I wouldn’t use them w/ 12V input at all.

Just use either or (first one has hi/lo/strobe, 2nd one is hi/med/lo) with two XM-L’s you have wired in series.

After you take this apart, you will have all the parts you need.
3 LED that runs on 12V, heatsink and an easy way to mount

I will show pictures later

EDIT: here it is

The best would be 3 XM-L in series, with a driver. One XM-L would be less efficient (probably does not matter).
About those 12V leds: I have one, my led is about 1A at 12V. You could connect it to 14.5V with some 2.5 ohm resistor for 1A, then 2.5W on the resistor, efficiency 83%, not bad. A driver will be better. There will be little current from 12V (probably does not matter, you don’t need light with engine not running).

Hi vieplis, did you really measure 1A WITH 2.5ohm resistor? That would mean a Vf of exactly 12V.

I read from other thread mentioning a 1.3A pull from 11.8V battery, meaning it's Vf is actually somewhat lower.

The problem with flashlight control modules is in the reliable factor. The Buckdrive is a 24/7/365 device that can take shock and variable voltage that your mower genarator/alternator will produce. Running two XM-L emitters in series @ 2.1A should produce adequate lightning with minimal heatsink issues. Read the pdf file for more info. I have used this controller on my 12 volt 48 watt solar panel hog light setup that runs two 3up XR-C (6 leds total) every night for over the last year.

This single mode driver will deliver about 2.5 amps to an XML from a 12 volt supply. They are super cheap and that’s about 800 lumen which wills seam extremely bright compared to an incandescent. Just solder some long leads onto it and glue it with Fujik into the housing.

Thanks for the responses. Thanks for that link Erik! Any suggestions on using a reflector or not? If so, what? I'm looking for floody light, so should I use a P60 OP reflector? Remember, this is behind the current headlight plastic lens.


plenty of cheap HID kits on Ebay

If I do end up doing this build, I'll be sure to post before and after "beamshots"! I intend on snipping the 12 volt leads in such a way that I can always splice the old bulb holders back in place should I have a need to.

By the way, last season I replaced the stock bulbs with these PIAA 27 watt Xtreme white ones. They did make quite a difference, but I'm looking for a lot more light! It's still so darn hard to see anything right at dusk!


EDIT - Added missing link.

For a "reflector", how about using these 60 degree optics from I.O.S.? (Seems I.O.S. keeps adding a lot of nice products, especially the "D.I.Y." products). I want the larger angle optics for a wider beam, right?

My other option would be a C8 reflector with these wide angle lenses (of which I have one). Problem there is how to mount them.


what I’d do is:

run 3 XM-L in series at 1A (or 1.5A max), bolt them onto the biggest CPU heatsink you can find and use 20mm elliptical optics. That’ll get you 7-900lm OTF and give you a manageable 10W of heat to dissipate within the confines of the existing headlight. The ellipticals should give you a wide beam that throws far enough for you to avoid the dog/ garden gnome/ etc but without wasting a whole load of light by throwing it up into the sky.

I’d go with a single mode driver and wire it into the existing switch set up. Buy several and rubber mount it where it’s easy to replace if a voltage spike kills it :slight_smile:

What i did was also from automitive batt (dunno if it make sense for your case).

Previously, i use car batt, wire out to my flashlight (tf-3t6) to be use as floody light for house in plantation. So far over 20 time, each time bout 9hours run.
**Buy a flashlight, remove the head (drivers+xml intact), connect + and - into it…

(Of course i do not know if that will be bang for buck in your case, i do it cos i do the easiest way w/o buying seperate & hv to solder them back)

Or, if u feel u need some light that shine towards your back, you can also direct run 12v wires to power SD 01 - 12v MR16 3w led (same as the light posted by dchomak), its only 270 lumen ber bulb. i am also powering 10 piece of them using 12v car batt only, no alternator, each run 10 hours, quite ok.

Hope it helps…

Could you just bike mout and wire too the dropin and body with a toggle switch where the tailcap was? Or drill a whole in the body and run the negative to the tailcap and positive to the dropin spring? Would the tailcap handle the amps?

Sorry to go way off topic, but that looks like a cheap and cheery maglite mod waiting to happen. Could you measure the diameter of the heatsink at its widest, and the depth of the heatsink and that plate together?

Thanks in advance!

50mm x 23mm

To measure I went over to my spare parts box and a there is a Mag reflector and this light sitting right next to each other!

Here is another, cheaper option

6000K Pure White

Thanks, dchomak! Worst case, the mag head needs a little trim at the bottom, it seems.

I’ve been staring at one of OldLumens’ 1d beauties for the last couple of days, and one of those might be just the thing. (Not that I’m too cheap to buy a ‘proper’ heatsink or nothing, but this is the land of budget, right? And if we’re going for full disclosure, it does hurt just a little to think about spending $15 on a spun hunk of aluminum.)