Upgrade a Maglite D with a 5x Cree XR-E R2 LED Drop-in Module

Hi all. This is my first mod of a flashlight and hopefully not last.

It was a group effort, my dad, my brother-in-law and yours truly. A nice Saturday evening of beer, chit chat and fun with flashlights. :)

We upgraded my dad's old Maglite 4D with a 5x XR-E R2 Drop-in Module from DX.

(Use this referral link to buy it, if you like my thread and want DX to give me some points.)

Since he didn't want to work with Li-Ion cells, we decided to keep his maglite on regular D cells. The drop-in I linked above works quite fine with 4 D cells.

We did not swap the stock switch, nor pretty much anything else. Most of the work was modding the maglite parts to make the drop-in fit.

If you are reading this you probably know how a stock Maglite D head looks like. Unscrew it and take out the stock reflector. Put the lens somewhere safe while working, you'll need to use them later.

Next, try to fit in the drop-in. You'll see that it doesn't fit. Either the drop-in or the stock maglite head needs to be modded. Wo chose to scrape off the excess material from the head. I somehow feel that shaving off the aluminum fins of the drop-in would do more harm to the drop-in than modding the head.

We used a drill bit that literally scrapes of stuff you put under it. Google says that's called deburring drill bit. My dad had one or two old ones, very similar to this one this one. His were VERY sharp and made of what looked like some very hard steel. Having the drill in the drill stand and holding (and moving) the mag head with the drill being in a fixed position is the way to go here.

Take care not to take off too much material off the head, rather scrape off little by little and check how the drop-in fits every few millimeters. Once you are satisfied the drop-in fits, leave the head and take care of the drop-in.

The original drop-in has two spring coils:

Next, unsolder both original coils.

Then solder a new positive contact that is thin enough to go into the stock Maglite bulb base/holder without coming to near the negative base contact. But be careful to make it thick and firm enough so it doesn't ever bend. I used a brass screw.

Assemble the new head, use your original lens, or swap with better lens.

This is the stock maglite bulb base. It moves up and down on it's own spring. Additionally, the center positive contact has it's own, separate spring. The positive contact is not visible on the picture, it's at the bottom of the threaded tube that you can see below. The screw I soldered to the positive contact of the drop-in will touch the positive contact of the base, but must NEVER touch the negative contact (threaded tube). That's why it has to be firm/rigid and not bendable. A really thick copper wire or a brass screw soldered to the drop-in center contact is perfect for this.

Next up, making the "adapter" for the negative contact. Stock maglite bulb base is too narrow for this dropin for my comfort. I never want it going near the center drop-in contact so I want to make it wider and at the same time keep it away from the positive contact.

Take some thick copper wire, a washer and make it! :)

Washer should be brass or copper so you can easily solder onto it. See below. Lacking a brass washer of the proper size we used a steel washer. Soldering was a bit problematic, but it turned out fine.

Inner diameter should be exactly the outer diameter of the maglite bulb holder tube, but without the threads, threads excluded. This washer must fit outside the bulb tube, but also must be stopped by the tube threads, not go over them. Outer diameter must be within few millimeters of the drop-in negative contacts, or roughly the diameter of the original large spring coil.

Take a piece of copper wire, roughly 2-3 millimeter thick and bend it into a ring shape.

Here is melting the solder so the copper wire will fall level with the washer. Here the washer is standing on another piece of metal, just so it doesn't stand on the wooden surface while I'm melting the solder with a gas torch.

Wire ring soldered to the washer.

Scrape off the solder dirt. Literally, it's dirt at this stage. You want this to be clean and corrosion free.

Put it onto the stock maglite bulb tube.

And carefully screw on the maglite head. Do NOT tighten too hard.

Here is the first problem we ran into. The maglite head doesn't screw far enough to cover the original head rubber o-ring. See picture.

Not to worry, we can modify the washer adapter. Grind off some material. Or use thinner wire to begin with. ;)

Unfortunately, while it helped, this still wasnt enough. Head still didn't comfortably cover the rubber o-ring.

I didn't want to grind off more material not to get too close to the center contact on the drop-in.

Not to worry, let's mod the stock bulb base.

Use whatever tool is at your disposal to cut off the plastic black tube that is around the brass maglite bulb tube. See pic. We used a miniature drill bit with a saw disc at it's top.

See the difference? The black part is much lower now. Try the mouseover on the pic above. Mouseover isn't perfect but you can clearly see the black tube is now shorter.

As you can see, the head now screws over the o-ring.

Unfortunately, after I got home I realized that I had no "money shot" of the drop-in through the lens. I'll have to correct that first opportunity I get!

Finally, here is a beamshot of the completed upgrade. I don't have the "before" beamshot, but trust me, it would be much less visible than that yellow streetlight in the distance.

This beamshot is some 12 meters away. About 40 feet. This wasn't in the absolute dark, you can see the yellow shadows from the streetlights across the street.

The funny thing is, his set of D batteries were more than a year old, cheapest supermarket non-alkaline version you can imagine. Used numerous times with the incan bulb. A year in the mag, inside the car. With temperatures from -10C in the winter to +60C in the summer sun.

Literally, there was no difference between the high and middle mode. :)

Which means, this was really poor amount of light compared to what a fresh set of batteries would give. The spot intensity was close to the intensity of my DRY NW at the same distance. Though DRY did cover almost the whole visible wall with the same intensity.

All this was measured by the very scientific "use your eyeballs" method.

After he gets some fresh batteries I expect I'll take more beamshots and post updates to this thread.

This covers most of the Mag LED upgrade. I hope you like it and at least someone finds it useful.

If there are any questions, I'd be happy to answer as best as I can.

Good modding!


Now, I have to add some comments, since I believe there is space for improvement here.

First thing that could be improved is the negative contact. With what I've shown above the head is screwed on the negative contact with almost zero spring. That means if the flashlight is dropped to a hard surface, or something hits it's head hard, it might (and probably will) break the drop-in base. I dislike that.

Next, the top of the head, the part that keeps the lens in place can't be screwed on all the way either. It can be screwed on sufficiently to cover the original o-ring, though. This is more a cosmetic thing, really.

Other than that I see no large objections. I hope to mod more Maglites like this. :)

Here is another attempt that we did of the negative contact adapter.

Unfortunately by the time we got this one together, it was already getting late. At the same time, while it looked much better, it proved not to have a reliable electrical contact, so we gave up for the evening. I expect the original ugly prototype will behave decently enough so we'll never get to finish this fancy version, but I might as well be wrong about that. :)

Here are some more pictures.

How we made the second adapter. Pictures are pretty self explanatory. A good hammer is needed (not shown in the pictures).

And here is the money shot I promised! :)

Next time, beamshot comparison against some other flashlights....


Great job! I did the DX XM-L drop-in into a 2D Mag (running (2) 18650's sleeved) and it was a bit of a bear to get right. I see your drop-in had a longer wide part to it - I didn't have to grind the inside of the head.

Would love to see it on good fresh alkalines! I wondered if that drop-in would work on alkalines even.


Fantastic! We need more modders to keep the hobby alive. Thanks for taking the time to make this thread and the photos with good detail!

Thanks guys!

It really was a pleasure. Modding, taking and editing pictures, putting together and editing the post all included. :)


I always love this kind of drop-in mod on Maglite!

My negative contact is much easier. https://budgetlightforum.com/t/-/2400

Thanks Viktor for documenting this thoroughly.

And special thanks for including your small mistakes! That helps us not to make the same mistakes if / when we decide to do the same / similar mod.

Keep up the good job!

Ps. I would have taken the cooling fins away instead of grinding the head. Cooling fins _inside_ the flashlight body just give more space for air (instead of aluminum) making the heat transfer worse.


I never understood how you made the negative contact. 8-|

Can you give me more details or a better explanation? Perhaps put it in your thread so whoever reads it can easily find it.



Sure, mistakes warn others of possible hiccups along the way and make you better prepared.

Since this won't be driven very hard for prolonged periods of time, I preferred to keep the drop-in cooling fins in their original state. But I do think the actual difference in heat transfer to the outside of the flashlight is negligible. Drop in has so little proper contact to the head that either way is good. I even think the better transfer to the air inside the head (and subsequently the outside of the head) is more important. Grinding the drop-in would make very small difference to what I did (in regard to air volume), but would reduce the drop-in heat radiation. All together I still think that keeping the fins on the drop-in was better to transfer heat.

Although, keep in mind that anodizing within the head is horrible for heat transfer. Whatever we are takling about here has several orders of magnitude less effect because of that anodizing.

Thanks for your comments. :)


Wow! Nice job and cool pics Viktor!

I've added more pics to post #2.

Making of adapter 2 and the promised Money Shot.



One of the best photographed mod ever. Good job! :slight_smile:

Wow! Makes my mag-mod look even more like a hack job. I noted the same thing you did about the end of the head not threading on completely; I painstakingly filed (by hand) the lip from the edge of the drop-in down to allow the reflector to recess completely into the head of the flashlight and the ring to be fully secured. That would probably change the fit of your other components though. In my mods, I completely remove the bulb post and add the JST connectors from DX to make as much room as possible inside the head. It also allows my mods to be removeable and modular...

Put heat shrink tubing around that postive post!

I think there's definitely room for improvement on that negative contact. JST connectors aren't a bad idea either. How do you put the head after connecting the JST?

How do you prevent whoever touches it from trying to unscrew the head and break the wires and contacts inside?

If you put the lens lid last when assembling and take it off first when disassembling, it's all good, but anyone who's ever held a maglite in their hand would first try to unscrew the whole head. Including me.

Yep, crew tried to unscrew my 3C mag mod first time they held it! I'm thinking of using loctite thread locker on mine. Can always unscrew the bezel to get the assembly back out.


Thanx for this guide. I’ve just finished modifying my 4D using a 6x Cree Q5 also from DX and the outcome was fine. The drop in also costs $3.10 cheaper.

Here’s the picture of my modified 4D:


Here’s my Mag4D 6xQ5 with some of my lights (BC40, K40, SRK & Terminator)


Here are their beams aimed at the ceiling. The 6xQ5 on the Mag4D is not bad at all: