Mag 4D Incan Mod plan- Please feedback!

[junglewarrior]

Maglite 4D - MR16 12v Upgrade

Hi all, i am going to attempt the following as my first flashlight mod;

I really want to try to do this mod using off the shelf kit from local DIY/Hardware stores, just to see if it is at all possible... So no battery adapters/custom built parts etc.

The Plan...

-mr16 lamp 12v (probably 20watt - nothing to powerful to start with) into maglite 4d.

http://www.lampspecs.co.uk/Light-Bu...Halogen-Spotlight-5K-Hour-20W-12-Deg-M268-ESX image for bulb type reference only - not my chosen lamp.

-Use a standard bi-pin bulb holder with wires.

http://www.ebulbshop.com/acatalog/MR16_LOW_VOLTAGE_GU5.3_BULB_HOLDER.html
or similar.

-Modify standard switch (cut down tower) and expose switch contacts.

-Solder bulb holder wires to switch contacts.

-Use an extra lens/'o'ring/improvise to secure lamp in bezel.

Using 1.5v D cells will give 6v - not enough voltage. So i'll use 5x 14500 batteries and run the lamp at 18.5v and overdrive it (quite a lot). I've read on here that people have taken these bulbs to over 20v and had no major issues. I'll use conduit/plastic tubing and a bit of ingenuity to make the size right.

Possible issues...

-Heat buildup in lamp. I will use a bulb with a metal reflector to send most heat outwards.

-Switch amps? I have no clue how to work out the ampage going through the switch. Up to 10a is OK (so i read...) - how much would the 14500's generate?

-Securing the lamp. I thought about using a wide, weak spring to go around the remaining switch tower and push up gently on the lamp from below? May add a degree of 'suspension/damping in case of dropping also.

So thats the plan - I cant wait to get stuck in. I plan on taking loads of photos so that if it works I can put up a mini how-to for a very low-cost mag upgrade.

Can you see any immediate problems with this build? Am I going wrong anywhere?

I will be putting the build together as soon as my new switch arrives on mon/tues so any advice will be greatly received!

Many thanks!

 

[lolzertank]

Forget about using 14500s. They can only generate 1A safely, which is not enough for a stock 20W bulb, let alone an overdriven one. IMR 26500 (C-size) cells are the best choice if you want to have 5 cells. I'm not sure if a 12V MR16 will survive the 21V starting voltage though.

The current through the switch is Power divided by Voltage. Pretty simple, right? A 12V 20W bulb, even overdriven by a ludicrous 300% to 80W is still within the 10A limit.

 

[junglewarrior]

Thanks for the quick reply!

I don't necessarily want to use 5 cells - it's the only way I could think of generating around 18v.

What battery configuration would you recommend for this set up? :-(

Power as in watts?
Please excuse the newbness. This last few weeks has already been a massive learning curve!

Thanks!

 

[UberLumens]

The 12V 6000 hour MR 16 love 21 volts and look nice no soft start nothing.

Cut and wired switch but used a refractory brick insulator and some ceramic wool to fill gaps, I made the bulb socket and insulator custom to save the switch from heat, the brick and wool are good to several thousand degrees.

put in 5 IMR26500 and let it rip, batteries were the most expensive part of the build

Buy a bulb for a few bucks and see how it fits, you shouldn't need the spring you mentioned

They dont like lower overdrive levels and look yellow and dull. 17-21 is very nice and white and bright

 

[junglewarrior]

Hi Uberlumens,

That build you done sounds exactly like the one I want to complete.

Have you got any pics of yours I could have a look at?

A refractory brick insulator and ceramic wool? Are these available from normal stores or are they a specialist material?

How did you make your bulb socket?

I'm going to order the batteries now.

Thanks for the advice so far!

MP

 

[alpg88]

i use 4x18650 in my 20w mr16 4dmag mod, i tried 5cells.brighter whiter beam, but light was too long, 4 cells ain't bad at all.
https://www.candlepowerforums.com/threads/276552

 

[UberLumens]

Sorry no pics at the moment ill snap some later

The brick and wool are not at all stores, you may have some luck going to a masony supply or fireplace shop to find the bricks.

refractory bricks are light easy to cut and insulate well at temps 4000f+.

Fireplace brick is much more difficult to cut and doesn't resist as much heat but is more durable. The ceramic wool you will most likely need to find online.

I have these around as a byproduct of my forges(one coal one gas) that were earlier projects(and work great!)

The socket i "extracted" from a lowes/homedepot spot lite(10bucks or so)


EDIT: you will need a battery sleeve, and for the tail cap just turn the spring over it will fit, bend contact for best placement on cells
Uberlumens

 

[alpg88]

A refractory brick insulator and ceramic wool?

what are those for????? i build about dozen of hotwires, from 20 to 150w, never used any of those, there is no need

 

[UberLumens]

Well two reasons,

One they are what i had to build the tower, and overbuilding wasnt a concern, underbuilding was, first light like this i made, didnt want it to melt anything, and it should be reliable for a long time.

Second if i want to put something hotter in there in the future no worries.(who knows what batteries and bulbs will be around the a year or so)

were they overkill, maybe, but it worked for me and i can run what ever i want until the mag head melts, my light tower and socket will still be fine.

(BUT, If you want, you can just cut tower, wire in socket and go. what ever floats your boat both will function)

 

[junglewarrior]

What size are the 18650's based on? Is it the CR123? I know I can fit 5 x 26500 as they are the same size as 'C'cells.

Could I fit 5 x 18650's? in a 4D Body?

Alpg88: Have you got any pics of the set-up behind the mr16?

Uberlumens I will look forward to seeing your pics if you get the chance.

At present I am thinking 5x18650's.

Have either of you got beamshots?

Sorry for all the questions! If you dont ask you dont know though eh?

Cheers!
MP

 

[donn_]

A D cell is 60mm long. An 18650 is 65mm long. Therefore, you can't get 5x 18650 in a 4D tube...without a hammer.

FiveMega used to sell extensions for Maglights. Others have had them made locally.

 

[junglewarrior]

Cheers Donn,

That scuppered my plan then!

26500's are back on the cards...

Am I best getting them from DX?

 

[UberLumens]

Here are some pics. If anyonce can help me thumbnail these i would appreciate it.

2d hand grooved/4d mr16

Bulb stays in socket, loosen head until contacts base when in use

socket with ceramic wool removed

socket with ceramic wool removed 2

Refractory brick towers, side wire version

battery holder with hinge

turn over spring, bend last coil for good cell contact

50w spot example

 

[MikeAusC]

The current through the switch is Power divided by Voltage. Pretty simple, right? A 12V 20W bulb, even overdriven by a ludicrous 300% to 80W is still within the 10A limit.

- this will give you the current through the switch once the filament has heated up. A cold Halogen bulb typically has one-tenth of its hot resistance - it's easy enough to measure if you know how to measure very low resistances.

So if a 12v 20w bulb draws 1.6 amps when hot, it will draw 16 amps at start at startup. Now you're going to overdrive it . . . .

 

[junglewarrior]

Wow that hotspot looks great!

I've been looking at battery options and for the time being i'm going to go with the 18650's as the 26500's are just too expensive for an untested mod.

Uberlumens - what bulb are you using there?

Alpg88: Do the 4x 18650's fit straight in with no length issues? Are you using protected cells?

Cheers!

 

[alpg88]

=Alpg88: Do the 4x 18650's fit straight in with no length issues? Are you using protected cells?

Cheers!

i use unprotected cells, 4th cell ends right where the thread starts,

 

[junglewarrior]

Now i've just picked up a bulb holder, already got a bulb just to try - a cheapie.

Batteries next 4 x 18650's from DX - best place to get them as I need a charger as well?

 

[alpg88]

just make sure you use some kind of soft start, or you will trip protection on cells everytime.

 

[junglewarrior]

Every time I think i've got all the kit I need there is always something else!

What kind of soft start switch did you use?

I'm really hoping for a low cost solution...

Cheers Alpg

 

[junglewarrior]

Would an LED mr16 equivalent require a soft start? As it draws less current it should run straight with no problems shouldn't it?

Hmmm...