Maglite Mini 2AA Mod Questions

Reziarfg

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Hello everyone! This is my first post here and I am excited to get into the swing of things. I sure hope this is going in the right place.

After picking up a couple lights I've become emboldened to try a bit of modding. And ambitiously enough I'm going to attempt an incandescent Maglite Mini mod.
Mostly just for fun, and because the host is lying around.
I've done a lot of scouring around here in past posts and it seems like:

  • There don't seem to be any parts lists
  • Most interest in Maglite mods dwindled away in the early-mid 2000s?
I've got a bit of background in the electrical know-how as well as a Hakko 888D. This is hopefully just a sanity check and fishing for advice.

So, originally, I was thinking to keep the light engine all in the head but I couldn't really think of a good way to keep things in place so I've shifted gears to a possibly more consistent battery-tube build.

So without further ado, here is what I am thinking:

PartDetailCost
ReflectorMcR-18 Reflector$17
Glass20mm AR$2.45
HeatsinkOFC Copper Heatsink$28
Driver14mm FET?$11.45
EmitterXHP50.2 on 10mm sinkpad$12
SwitchKroll Tailcap$4
Power2x14500 protected 750 mah cells$16
Thermal CompoundArctic Silver or similar$6
Total---~$97

















I think I have it mostly sorted out but the driver in particular I'm unsure about. Can an XHP50.2 handle that?

The heatsink came from this post and seems like a good solution for the "pill retention problem"
And here is the build process from that same thread:

pURLgw4.jpg
 

Jeepster04

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Excited to see what becomes of this. I've got several old mini mags that I would like to mod.
 

pc_light

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Welcome to CPF Reziarfg, that's going to be some hot-rod.

If you haven't planned to already you'll need to include an isolating/insulating LED spacer, I only mention it because it's not listed on your bill of materials. Between the aluminum McR and the short lead distances of the 10mm mcpcb you'll probably need one.

The batteries you've choosen will probably self-limit the current going through your mod, because with high-drain batteries I could see the Kroll switch getting overwhelmed.

My last AA mini-mag mod was nothing so ambitious just XP-L driven 1A with a NiteIze tailswitch added recently. It's still running great though.

Looking forward to seeing the results.
 

Reziarfg

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My last AA mini-mag mod was nothing so ambitious just XP-L driven 1A with a NiteIze tailswitch added recently. It's still running great though.

How do you like that tail switch? It was one of the first I came across and I almost went for that one instead. But some report it's a bit mushy.

My biggest fear to be honest is that the LED won't handle the 8.4V from the FET driver very well. But I can't find a buck driver in 14mm.
 

pc_light

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The Niteize switch works fine but it is also probably not able to take high current. Despite the unusual shape the Kroll is fine, my comment only pertains to your mod powered with 2xhigh drain cells, shouldn't be a problem as is.

Hmm, forgot about possible over-voltage with emitter. Battery sag and the innate resistance (including the switch) might reduce enough to be ok. It could also be that Mtn somehow reduces the voltage (divider?) as part of the Zener mod in order to protect the MCU as well, you would need to ask Richard at Mtn.

I know this completely changes your hot-rod-mod but there is a recently released 3V XHP50.2 that is receiving good reviews. Running 2x1.7V cells or a single 4.2V cell with dummy spacer might be an option.
 
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Icarus

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I like your attempt to mod the MiniMag (I've done several myself) but none of the switches I'm aware off will be up to the job for this mod. In best case they can withstand 1.5A. I would avoid the Kroll switch because it's unreliable even at low currents.
 

light-modder

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I did a mule xhp50 mod for a little while. Used two IMR 14500s but the fet drivers weren't out yet so I had a few 7135 chips added though I don't remember how many. It got hot and fast but was pretty cool.
 

Reziarfg

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In best case they can withstand 1.5A. I would avoid the Kroll switch because it's unreliable even at low currents.

Hmm. I didn't know that. Is there an alternative? The build process for that ofc heatsink says a switch is required and shows a kroll one I believe. What are the alternatives if leaving it twisty doesn't suffice?

EDIT: Looks like the requirement for a tail switch is due to this mod defeating the twisty power-on configuration of the original light. Now I have to find a tailcap that can support a 2S 8.4V light? I don't even know where to start with that.
 
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Icarus

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As far as I know there isn't a high current tailcap switch for the MiniMag AA readily available. I'm using a switch like this one but it's also only for use with low current mods. For high current mods you should put the driver in the head and switch the light on/off by turning the head down/up. The driver should then make contact with the top of the body (negative contact) and the top of the battery (positive contact).

The heatsink you are using is ok but then you need a tailcap switch to turn the light on/off and since there isn't a high current switch readily available you will be limited to a low current mod or have to make your own switch which I think has no one done before. :shrug:
 

Icarus

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FYI the switch in my link can be found on ebay. Unfortunately they are only available in black. They are the best alternative for the Kroll switch. Nite Ize is selling an upgrade kit for the MiniMag AA which also contains a tailcap switch. However this switch is not as good as the one in my link.
 
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bykfixer

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The Nite Ize clicky is glitchy. Sometimes it doesn't work proper even on a stock minimag. Flickering or finicky turn on have been my experience.

Agreed the most reliable would be cut/restore the circuit at the front end.
 

Reziarfg

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The heatsink you are using is ok but then you need a tailcap switch to turn the light on/off and since there isn't a high current switch readily available

Thanks for the insight. Looks like I may have to fall back on a lower current build. Unless, is it possible to use the tail switch with a simple spring bypass? Would that be all I'd need to do?
What bothers me is it's so hard to do the math for these. I don't know what current it can or needs to handle.

EDIT: Also if the batteries are protected and shut down at 3A would that be a problem? What stops the LED from pulling more than that?
 
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Icarus

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Thanks for the insight. Looks like I may have to fall back on a lower current build. Unless, is it possible to use the tail switch with a simple spring bypass? Would that be all I'd need to do?
What bothers me is it's so hard to do the math for these. I don't know what current it can or needs to handle.

EDIT: Also if the batteries are protected and shut down at 3A would that be a problem? What stops the LED from pulling more than that?

I couldn't find which Vf your LED has but since you are using 2 li-ion cells in series I assume you choose the 6V version. Then the driver probably has the Zener mod and the 6V LVP?

The spring bypass for the switch will help but time will tell if this is enough for the switch to survive. All depends on the current that goes through it. The XHP50.2 @ 6V is rated for 3A max but since you are using protected cells the protection circuit might kick in earlier. Try it, it needed you can still use high drain IMR cells.
 

Icarus

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EDIT: Also if the batteries are protected and shut down at 3A would that be a problem? What stops the LED from pulling more than that?

Ths software in the driver limits the current (by PWM).
 

Reziarfg

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I couldn't find which Vf your LED has but since you are using 2 li-ion cells in series I assume you choose the 6V version. Then the driver probably has the Zener mod and the 6V LVP?

The spring bypass for the switch will help but time will tell if this is enough for the switch to survive. All depends on the current that goes through it. The XHP50.2 @ 6V is rated for 3A max but since you are using protected cells the protection circuit might kick in earlier. Try it, it needed you can still use high drain IMR cells.

Thank you. You've been super helpful.
To be honest I got impatient and just bought both the protected cells that should do well up to 3A and another set of unprotected IMR 6.5A cells.
At worst this will just be an excuse to pull the trigger on a 14500 Zebralight or something. :shrug::twothumbs
 

yazkaz

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@Reziarfg
Glad I found this thread. Were you the guy who bought one of those OFC heatsinks?

Anyway your proposed MagAA setup poses a problem. Why? Because the MagAA is supposed to be of a simple, everyday setup which doesn't require complicated battery setup. In other words, you want to stick to 2xAA instead of 2x3.7V (2x14500) whenever permitted.

Also for such a MagAA mod you want to limit the drive current to up to 1A, or less -- depending on your preference in output or runtime. And the overall heatsinking is also a problem since this is to be a makeshift LED setup but not a native one. The OFC sink does help a bit, but still the MagAA host is a relatively small one so overrunning the light module would still render the host to be quite warm (if not hot) -- especially if you drive the LED at more than 1A.

Here are my proposed components:
Optic: a shallow (ie. short) reflector or colliminator optic is needed. Otherwise, with the head assy it won't be able to screw down completely onto the body, due to lack of threads. And lack of threads means the head would wiggle very badly.

As for the choice of McR18, you'll need to shorten it from both sides to cap the total height to less than 10mm;

Lens: 20mm is too narrow. For the MagAA chassis you'll need 22.5-22.61mm in diameter. Thickness will need to be around 1mm, or no more than 1.5mm. Too thick of the lens and youj'll have problem screweing in the bezel ring effectively;

Driver: Sandwich Shoppe 0.55" driver for sure, especially the Nexgen boost drivers. My personal choice would be NG1000. Anything below 917mA would yield a very low output IMO;

LED: XHP50/2?? No freaking way! It's going to be VERY hot and is thus not suitable for MagAA use, even with the right battery combo. For such LED usage you'll need a Mag C/D mod setup which is a completely different story. For MagAA usage you want to stick to Cree XPG2/3 or even Nichia 319a/b. A ~8mm MCPCB is needed for these emitters.

Also you'll need an emitter with the right Vf. XPG2/3 and 319a/b have low Vfs of around 3V at 1000mA, suitable for most 2xAA combos (NimH, L91 single-use Lithium etc.)

Thermal cpd: You need thermal epoxy (a+b). Everything needs to be stuck together for the heatsinking system to take effect. Just thermal paste (Arctic Silver 5, Ceramique 2) is not enough.

Hope that helps...
 
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Reziarfg

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Oh boy there's a lot to unpack here.
Firstly, thanks so much yazkaz. Yes that was me!

And yes I've conceded that I won't be able to put together a ridiculous hot-rod as I had hoped initially.

For the McR-18 reflector I noticed it was a bit too long when I purchased it which is fine. I'll take care of that with a bit of filing.

What I ended up going with is actually a Nichia 219C D240 on a 10mm sinkpad. I'm hoping I didn't make a mistake here since you indicate 8mm. Is it going to be impossible for this one to fit? 10mm seems to be the smallest available sinkpad I could find.

I'm wondering if I made a mistake with the driver though since I did see the .55" sandwich shoppe one but ended up going for a 14mm (.55") FET from mtn-electronics. I think it'll be compatible? No zener mod, so the voltage input should be right.

I have AA NimH in case I need to, but I was hoping to actually get away with a 1x14500 and x1AA dummy though I don't know if that would work. Hoping it does.

I also had ordered RTV black silicone sealant which I'd heard was suitable for these sorts of things. Correct me if I'm wrong.

Looks like I may have to purchase a larger diameter lens though. Thanks for that
:)


As a sidenote, I did still pick up an XHP50.2 which I may try to configure into a mule fully enclosed in the head with a larger chunk of copper in a completely separate mini maglite.
 

yazkaz

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Oh boy there's a lot to unpack here.
Firstly, thanks so much yazkaz. Yes that was me!

And yes I've conceded that I won't be able to put together a ridiculous hot-rod as I had hoped initially.

For the McR-18 reflector I noticed it was a bit too long when I purchased it which is fine. I'll take care of that with a bit of filing.

What I ended up going with is actually a Nichia 219C D240 on a 10mm sinkpad. I'm hoping I didn't make a mistake here since you indicate 8mm. Is it going to be impossible for this one to fit? 10mm seems to be the smallest available sinkpad I could find.

I'm wondering if I made a mistake with the driver though since I did see the .55" sandwich shoppe one but ended up going for a 14mm (.55") FET from mtn-electronics. I think it'll be compatible? No zener mod, so the voltage input should be right.

I have AA NimH in case I need to, but I was hoping to actually get away with a 1x14500 and x1AA dummy though I don't know if that would work. Hoping it does.

I also had ordered RTV black silicone sealant which I'd heard was suitable for these sorts of things. Correct me if I'm wrong.

Looks like I may have to purchase a larger diameter lens though. Thanks for that
:)


As a sidenote, I did still pick up an XHP50.2 which I may try to configure into a mule fully enclosed in the head with a larger chunk of copper in a completely separate mini maglite.
I'll try to keep it short here.

McR18 -- Precision machining is needed, but another issue is how to do the machining effectively such that no metallic dust would get into the reflector's parabolic surface, or risk permanent damage to it. I've been there before so I'd rather stick to my Khatod optics;

Battery -- if you want to use 1x14500 with dummy contact spacer then you'll need the GD1000 buck/boost driver. With the NG1000, your LED's Vf is probably too low such that the driver may exceed the +0.7V overvoltage tolerance too easily, thus destroying it;

Driver -- No comment on anything beyond the SS. But the SS drivers have detailed specs listed so you'll have a good idea what they can achieve, and vice versa;

LED -- Definitely no XHP50/2. AFAIK it's Vf is actually around 6V (can someone here confirm?). And underdriving an LED means you're not utilizing the LED efficiently;

Sinkpad -- You'll have to measure the diameter of the collar on the copper hearsink. An MCPCB at less than the measured diameter should do. Do remember that the light module is to be transferable from one host to another, so it needs to be readily removable.

So I may not be all correct regarding the above, if I ever make a mistake please correct me. Thx...
 

Reziarfg

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Thanks again, yazkaz.
I am definitely NOT planning on putting the XHP50.2 into there. I am aware it is a 6V LED and was planning on a 2S 14500 build but I'll have to find something suitable to put it in. I take your experience on this very seriously and of course will not attempt such a thing. Since you've discouraged it so strongly.

Looks like I'll need to be picking up an NG1000 at Sandwich Shoppe after all.

I hope this is the right one. It would be nice to use a single 14500 with a spacer if possible though. I was having a hard time figuring out the GD Buck/Boost at SS though. Can I just choose the blank and put in two 0.10 resistors for 1A output? I think that's all that's necessary. It looks like that would allow either 2AA or 1x14500 and the spacer which would be a very nice option to have.

Thanks again so much for the insight. I know I am being very ambitious for a first build here.
 

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