# Upgrading Maglite 3D and 4D to Terralux Ministar31m-ex using 1/2 D cell



## Webster (Jan 27, 2012)

Hello folks, been reading CPF for a while here and there as I've always loved flashlights.&nbsp;&nbsp;&nbsp; However,&nbsp;I dont do many mods to my lights but I'm finally getting around to modding a 3D and 4D Maglite.&nbsp;&nbsp;&nbsp; Main driver for this project is that my Stanley HID runtime just isnt enough when walking around my property.<br><br>I'm aware of all of the AA packs and adapters, but after doing some consideration of both output and runtime, I'm thinking of getting a Magcharger pack made by Powerizer for the 3D.&nbsp;&nbsp;&nbsp; That seems like a simple choice and Terralux themselves have tested&nbsp;it and liked the output when I talked to them on&nbsp;the phone. &nbsp;&nbsp;&nbsp;&nbsp; For the 4D I calculated that seven 1/2 D cell batteries could just barely fit.&nbsp;&nbsp;&nbsp;&nbsp;Four standard&nbsp;D cell are 246mm and&nbsp;seven 1/2 D cell add up to 252mm.&nbsp;&nbsp; I added a 7mm spacer to my 4D and it fit so I'm thinking the seven 1/2 D cells will work.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;I'm aware of the downsides of D batteries for chargers but I already have one, and was thinking of picking up a Magcharger spare charger that can handle up to six 1/2 D cells,&nbsp;so theoretically I could charge the&nbsp;1/2 D cells in that stacked.&nbsp;<br><br>Has anyone here tried this approach?&nbsp;&nbsp; Am I missing something important?&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Last but not least, I'm assuming the Powerizer 1/2 D cells available at 3500 mAh are the same cells they use in their Magcharger 3500 mAh pack.&nbsp;&nbsp;&nbsp; Comments?<br><br>Appreciate the feedback.&nbsp;&nbsp;&nbsp;&nbsp; As an aside, Terralux&nbsp;said the Ministar can handle up to 14V on the phone.&nbsp;&nbsp; Assuming I was talking to someone who knew what they were talking about, that leaves many other options with series/parallel and 3.6V&nbsp;battery packs, but just trying to keep it simple.&nbsp;


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## Stephen Wallace (Jan 27, 2012)

Webster said:


> Hello folks, been reading CPF for a while here and there as I've always loved flashlights. However, I dont do many mods to my lights but I'm finally getting around to modding a 3D and 4D Maglite. Main driver for this project is that my Stanley HID runtime just isnt enough when walking around my property. I'm aware of all of the AA packs and adapters, but after doing some consideration of both output and runtime, I'm thinking of getting a Magcharger pack made by Powerizer for the 3D. That seems like a simple choice and Terralux themselves have tested it and liked the output when I talked to them on the phone. For the 4D I calculated that seven 1/2 D cell batteries could just barely fit. Four standard D cell are 246mm and seven 1/2 D cell add up to 252mm. I added a 7mm spacer to my 4D and it fit so I'm thinking the seven 1/2 D cells will work. I'm aware of the downsides of D batteries for chargers but I already have one, and was thinking of picking up a Magcharger spare charger that can handle up to six 1/2 D cells, so theoretically I could charge the 1/2 D cells in that stacked. Has anyone here tried this approach? Am I missing something important? Last but not least, I'm assuming the Powerizer 1/2 D cells available at 3500 mAh are the same cells they use in their Magcharger 3500 mAh pack. Comments? Appreciate the feedback. As an aside, Terralux said the Ministar can handle up to 14V on the phone. Assuming I was talking to someone who knew what they were talking about, that leaves many other options with series/parallel and 3.6V battery packs, but just trying to keep it simple.



Hopefully that will be easier for people to read.


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## moodysj (Jan 27, 2012)

yes, thanks!


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## Webster (Jan 27, 2012)

Sorry about that getting messed up, not sure what happened, looks like the browser refreshed. Anyway, hopefully someone has some comments on the 1/2 D option. I talked to Battery Junction today and they could not confirm if the Powerizer 6V pack used the same 1/2 D powerizer cells they sell. Typical customer care stuff. I must say though, Terralux has great customer care, very easy to get a technical sales or tech person on phone


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## fivemega (Jan 27, 2012)

*1/2D cells are not efficient even 3500mAh versions.

Charging above pack (7 serial connected 1/2D cells @ 3500mAh) with stock MC charger will take 24 hours.

You can simply use 3 protected 18650 (3100) in 3D M*g and get (11.1 volt @ 3100mAh) over 34 Wh versa NiMH 1/2D (8.4 volt @ 3500mAh)29Wh

Much smaller in length, much lighter in weight, low self discharge, longer run time and quicker recharge.*


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## Webster (Jan 27, 2012)

Thanks Fivemega, that a good suggestion but I don't have an Li-Ion chargers yet. I've considered the other battery packs I can build. I'm trying to capitalize on existing infrastructure around the house. 
I have a Nicad/NIMH charger already and can get the Magcharger ones for almost nothing. Not so concerned about weight and charge times, more concerned about fit (my calculation says yes, but I could be off a mm or two) and also curious if the 1/2D 6V packs are built from the same 1/2 D cells. This would allow me to purchase a Magcharger 6V pack then add on 2 cells. These components are also very cheap on Craigslist. 
Nonetheless, it isn't so much money either, just trying to recycle parts too. Regardless, I think your suggestion is excellent and I'm not ruling it out. If I were to go Li-Ion I'd probably build three 3.7Vin parallel pack and then put 3 of those packs in series. I haven't measured to see if they fit like the three AA to D but I think they would.


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## DecentMan4you (Jan 29, 2012)

*Re1 Upgrading Maglite 3D and 4D to Terralux Ministar31m-ex using 1/2 D cell*



fivemega said:


> *1/2D cells are not efficient even 3500mAh versions.
> 
> Charging above pack (7 serial connected 1/2D cells @ 3500mAh) with stock MC charger will take 24 hours.
> 
> ...



How do you make the 18650 fit in place of the D cells? 
Is there a adapter that can be bought to put the 18650 inside of to prevent rattling and also to hold straight inside of the battery tube of the common D cell flashlight?

I am considering purchasing one of these http://www.ebay.com/itm/330677549829?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 *TERRALUX POLICE 4 to 6 D CELL MAGLITE FLASHLIGHT LED BULB 1000 LUMEN TLE 310MEX

**CHOOSE SINGLE MODE or MULTI MODE with 1000 LUMENS*



and am curious of how to utilise 18650 batteries now that I have seen and read this thread.


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## fivemega (Jan 29, 2012)

*Re: Re1 Upgrading Maglite 3D and 4D to Terralux Ministar31m-ex using 1/2 D cell*



DecentMan4you said:


> How do you make the 18650 fit in place of the D cells?



*Use a PVC pipe with 3/4" inside diameter and about 1-1/4" outside diameter and 7" long. You may have to combine 2 different PVC pipes.

Another choice for even longer run time is using 2P/2S M*g 2.5D with 7.4 volt @ 6200mAh and over 45Wh*


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## RichM (Jan 31, 2012)

*Re: Re1 Upgrading Maglite 3D and 4D to Terralux Ministar31m-ex using 1/2 D cell*



DecentMan4you said:


> How do you make the 18650 fit in place of the D cells?



For 2x18650 in a 2D light I use 3/4" PVC with half of a coupling on each end to center it in the flashlight.

I make a series of them end-to-end and then saw through the couplings. I can make quite a few in a short time. A tiny amount of adhesive before sawing to keep the coupling on. (I mount a fine tooth blade backwards on the saw for a clean cut.)

Overall length (not all that critical):
2D (2x18650) = 5" (127mm)
3D (3x18650) = 7 1/4 " (184mm)


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## Webster (Feb 3, 2012)

I have this Ministar 31m-EX up and running at 6V and it is wicked bright and has a much better spot beam unlike the older 300 model but also has floodlight spill. It also has a smoother round pattern shined close up on walls. Overall I'm quite impressed with just 4 D alkalines. I'll probably purchase another since I have so many maglites.

Has anyone calculated the light output versus voltage or power consumption on this unit? I would imagine there is much more output to go but it is impressive now. There are surely diminishing returns at some point but maybe worth investing more...?? I'll be testing it at 7.2 and 8.4V NiMH soon and check the power consumption and compare light output.

I have a Stanley HID and while this is not as bright it is just as useful for things close range, say less than 100 feet. Very blinding white light, would disorient an intruder for sure. Pleasing color at least to me. 

I see now there are Li-Ion D cells out there, I think even protected. If so that may be a great upgrade for the 3D mag, has anyone tried these?


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## needforspeed (Feb 3, 2012)

2 cell D maglight with a tle 310m-ex and a pair of Novae 32650 Lion's works great. I did have to widen the tail cap a bit with a dremmel to fit the battery inside and move the spring to the bottom of the cap, but 20 mins of work makes for a cool light in my opinion.


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## Webster (Feb 3, 2012)

Needforspeed, that sounds like a nice setup. I havent had time to investigate all of the options on 32600 and 32650 but what stopped you from using the 32600 size since they are almost identical to D? Perhaps I'm missing something on which Li polymers and which are available protected at this time. Just casually looked at it. Regardless, I can comfortably say that the 310m-EX is a cost effective upgrade for a insanely bright flashlight, especially for those who have buckets of maglites around.........I'm noticing dozens of $5 and $10 5 and 6 cell mags on Craigslist too.


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## needforspeed (Feb 5, 2012)

32650's were on the shelf and needed a home LOL. When i do it again 32600 will be the way to go.


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## Stephen Wallace (Feb 5, 2012)

If we are talking about protected LiCo cells, the bare cells may be 32600 in size, but the added length of the protection circuit takes the cell to 32650 anyway.


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## Webster (Feb 6, 2012)

Thanks Stephen, that is a good information. I'll admit I havent paid enough attention to the normal development cycle of new cell sizes. I suppose they put new ones out unprotected, then slowly add protection and target certain sizes as energy density improves.

Nonetheless, this unit is very impressive at 6V. So much so that my neighbor went and ordered one for his Magcharger.


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