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  1. #1
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    minewt something or other XM-L upgrade

    I didn't actually mean to do this yesterday as I ended up using one of the LEDs for my next build, but I wanted to see if it worked or not (and apologies to BikerNY if I jumped his gun with beamshots).

    anyway, a friend that I ride with had a minewt something or other that had an intermittent connection problem. I said I'd give fixing it a go and, while I was at it, did he want the LED upgrading? Obviously, he said yes.

    funnily enough, I've upgraded the LED, but gave up trying to find all of the breaks in the wire going to the battery (fixed 4 of the buggers) so it still doesn't work properly, just long enough to get beamshots. He'll have to wait until an extension cable arrives at the LBS for me to hack up.

    Right, first up, original beamshot. It's crap, sorry. It started to rain and keeping the damn thing on for 2s was trying at best.



    here's the P4 and doodad board, unceremoniously chopped off the battery lead



    XM-L T6, wired up. Yellow (voltage sensing?) wire chopped off flush to the end of the cable. LED star had to be filed down slightly to fit and the 2 neutral cut outs (the bits between the + and - traces) dremelled out a bit to line up the the doodad board screw holes.



    if you take out the plastic rings on the screws, they're just long enough (one on the right was a longer screw I had laying around), otherwise you won't get the star sitting flat

    unfortunately, +ve wire routing required some hacking of the reflector, plus some filing to fit over the XM-L (I was so glad it worked, didn't fancy trying to put it back to its original state..)





    it was a complete and utter arseache getting the reflector to stay put AND the cover glass not falling out of the other half of the light body, so I 5min epoxied the reflector in place





    I also put a thin bead of silicone around the O-ring and squashed the cover glass onto it (it was really starting to pee me off, it's like it's spring loaded or something). No pic of that though. Actually, no pic of it reassembled - it looks just like it did, obviously. Fitted together perfectly fine, perhaps a smidge of space between the cover glass and lip of the reflector.

    test shot (2s, little sunshine symbol, garden shed is actually small, not a barn far away)



    again, minewt P4 (not directly comparable, rain etc)



    minewt XM-L @1A



    commuter light (XM-L T6 + Regina), ~300mA (L3, when L5 = 1.2A)



    commuter light 1.2A



    I think the upgrade was worthwhile. From ~175-200lm to ~300lm theoretical. Spot is a bit wider than stock (similar to a Regina I think, but with a sharper spill cut off) but overall a lot brighter.

    Now I just have to replace that blasted battery lead

  2. #2
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    very nice!

    it's so hard to believe that just a few years ago the P4 was at the top of its class....and we all got excited when it was released. haha
    I WANT TO BUY YOUR MAGICSHINE LIGHTS! Working or not.

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    If you spun the star 60 degrees, you would have had two terminals close to the bottom. I don't know if that would have made things easier or not.

  4. #4
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    Quote Originally Posted by BKruahnndon
    very nice!

    it's so hard to believe that just a few years ago the P4 was at the top of its class....and we all got excited when it was released. haha
    thanks! I think I would have been pretty happy with one of these minewts a couple of years ago and blown away by the XM-L version. They're really rather tidy little lights, flaky cables and connectors aside.

  5. #5
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    Quote Originally Posted by MrLee
    If you spun the star 60 degrees, you would have had two terminals close to the bottom. I don't know if that would have made things easier or not.
    thanks for the idea MrLee. I thought about that, but I didn't know if grinding out an indent (is that the right word?) on a +ve or -ve trace to fit the screws would have been an issue. I was kinda worried about causing a short. Any body have any views on that?

    I'll no doubt have a bunch of people lining up for the upgrade (LBS was a stockist until recently) so I'll give it a go next time as it'll definitely save time and effort.

  6. #6
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    Nice improvement there and the beam looks surprisingly good for having to be hacked to fit. I really like the mini-nwets design (style-wise), but not so much the LED's anymore. This mod really puts a new life back in them.

  7. #7
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    thanks I think a Regina might fit in there, so I'll give that a go next time - the reflector shape looks similar, but the Regina seems to give a tighter hotspot AND more spill.

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    Quote Originally Posted by mattthemuppet
    thanks for the idea MrLee. I thought about that, but I didn't know if grinding out an indent (is that the right word?) on a +ve or -ve trace to fit the screws would have been an issue. I was kinda worried about causing a short. Any body have any views on that?
    I think the traces on those stars are as below, don't think it would have been an issue for you -



    60 degree rotation would have given you -


  9. #9
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    thanks MrLee, I'll give it a go with the next one

  10. #10
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    a quick heads up and request for advice

    so, I fitted the new cable last night (hacked up extension cable) and...

    it still powers off after 2s. My guess is that the yellow wire is used for voltage/ connection monitoring and when there's a break in it (original problem) or it's not connected (now), the driver thinks something's wrong and switches the light off.

    any ideas? I haven't opened the battery up to check out the driver yet, do you think there's a way to circumvent whatever that yellow wire does?

    options
    a) put it back to what it was (PITA as I've trimmed the reflector, plus it would be an admission of DEFEAT!). Cost: free, much cursing

    b) see if I can jam the original LED board behind the XM-L so I can connect the yellow wire. Cost: free, much cursing + fiddly soldering

    c) open up the battery pack and randomly jab the soldering iron at the driver. Cost: free, much cursing and I'll probably completely screw the light

    d) open up the battery pack and replace the driver with an Lflex (I think the switch is a momentary switch). Could even make a new battery pack with a 2 cell holder and the other half of the extension cord (hopefully charging would still work). Cost: $30, less cursing + better light.

    thoughts?

  11. #11
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    it works!

    Right, had a bit of a fiddle.

    First, disassembled the battery pack (massive driver BTW) and disconnected the yellow voltage monitoring wire from the 2S battery. Light then didn't work at all. Reconnected everything, reset the driver with the charger and now it's back to working for 2s.

    Next, I decided to see if the LED board could be flipped over and stuffed underneath the XM-L. After some v. careful drilling I enlarged the screw holes so that they slipped over the screw posts and the board fit beneath the level of the heatsink post.

    Wired up the LED board as before, but on the backside (components facing towards the back of the light), then ran 2 wires from the LED pads to the XM-L - BINGO, worked perfectly. Then cut down the XM-L so that it cleared the wires going to and from the LED board, soldered in a bypass for a trace I nicked when drilling out the holes, and ground some material out from the housing around the heatsink post, and it all fit perfectly.

    Now I just have to trim the reflector to fit around the wires and it'll be done, phew!

    Pictures to follow.

  12. #12
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    so, scratch the above pictures, look at these instead!

    hacked up XM-L star sitting over the inverted LED board


    and a poorly taken closeup, where you might just be able to pick out where the cable ends are soldered onto the old LED board.


    bit of a faff all told, but the next one should be easier

    Should be around 380lm theoretical, give or take, so double or more of the original (depending on whether it was the 150 or 200).

  13. #13
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    done 3 of these now, tried something different with the 3rd one so that a) I didn't have to find some longer screws and b) the voltage warning lights were still visible

    driver board, note bits at top


    top bit of driver board cut up and soldered to + and - pads of LED, plus the yellow wire (voltage sensing). 1:nil in Matt vs. The Mozzies


    all together again. 2:nil in Matt vs. The Mozzies (although I think it went 2:1 a little later)


    considerably quicker and easier to do and, although the reflector needed trimming to allow the hacked up board to fit, I could still use 2 of the locator pegs on the reflector. Everything, including the status LEDs worked perfectly (phew!).

  14. #14
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    Nice work, that is tight quarters to fit all that stuff in there. This is the type of thing I really hate soldering, takes a steady hand and loads of patience getting the wires to lay where they need to be. Was looking at the board and I know it was mentioned before that a clean cut will not expose the conductor, but I'd try sealing the cut edge with some nail polish or something just to be safe (don't see anything on this one that looks like it would short, but the thought gives me the willys thinking about having to rebuild it.

    Also, I think you could ditch the board all together if all you need is to fix the sense wire. It looks like the 2 resistors that you connect the yellow wire to are the same, so the voltage on the yellow wire should be 1/2 the voltage though the LED, it is called a voltage divider:

    http://www.doctronics.co.uk/voltage.htm

    Looking at the board the resistor voltage divider is in parallel with the LED. I guess that the yellow wire normally connects to the back of the board where the "R4" is located (at the middle of the divider.

    The resistors they use are 1.3kOhm (132 if I am reading it correctly - tiny):
    http://www.hobby-hour.com/electronics/smdcalc.php

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    thanks Huffy. It wasn't too bad other than trying to get that sense wire soldered between the 2 resistors. I did mean to coat the solder joins and edges of that board with liquid tape, I just forgot . It's actually easy to take apart, so if my friend has issues it won't take long.

    you're right, there is a track directly from the yellow wire to the centre of those 2 resistors. I initially thought about just cutting that bit out, which would be a lot easier to fit, but I didn't know if the other resistors were just for the stat LEDs or also had some role in the voltage sensing. Plus, I figured that keeping those LEDs would be kinda cool if I could manage it.

    I have some other non-stat LED minewts that I might be upgrading so I'll see if I have any resistors of those values to do away with the board entirely - it'll certainly make my life easier

  16. #16
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    Nice work Matt.
    How does it cope with the heat? I ask because it doesn't appear as though the star is mounted to a heatsink

  17. #17
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    thanks emu! The original design has the P4 or other LED sitting on a post that protrudes through that green doughnut shaped board (one of the reasons why NR are only just changing the LEDs in the MiNewts) . Now the XM-L is sitting on the same post with thermal paste, though you have to be careful with adjusting the screws either side to make sure it sits flat.

    Current should be the same, although it will probably run cooler/longer due to the lower Vf of the XM-L.

  18. #18
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    Matt, this is a fantastic thread. Thank you for taking the time to post up the information. I have an older MiNewt.X2 I'd like to attempt to upgrade.

    Is the best way still to hack up the driver board and mount it over the XML star? Or, has someone come up with a better approach?

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    thanks marpilli, this is a blast from the past! I actually have a couple to do at some point, so I have a few things to try. One is to try and cut out the sense resistor and tiny LED from each side of the board, then wire them back together with some thin gauge wire so that I have more space and freedom to position them. Second is to try Huffy's suggestion of simply wiring up 2 1.3kOhm resistors between the yellow sense wire and the +/-ve LED pads. This would be ideal for lights without the battery warning LEDs in the light head.

    I might also try and see if a Regina reflector will fit in there as the XM-L has a much wider beam than the original LED and might be too wide for some.

  20. #20
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    Is there any particular XM-L manufacturer/part number you'd recommend? I know my way around a soldering iron, can read basic schematics, and have a functional understanding of electronics. But, I've never done any work with lights before.

    Also, in post #13 (photos 2 & 3) it looks like you're a mosquito collector? On the vice...

    EDIT: I get it now. Mozzies = mosquitoes.

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    me and mozzies are not the best of friends

    For LEDs, you pick the bin (brightness range) and tint (greeny white all the way through to pinky white). The brightest XM-Ls are U2 bin and they tend to come in 1A or 1D tints, which are cool white. Personally, I prefer neutral white (3C is what I've used) which only come in T6 bins, so search for XM-L T6 3C.

    You can get them cheap from China (as low as $4 now), but there's no guarantee of what bin or tint you'll get, irrespective of what they're selling them as. I've also had some QC issues with LEDs from CNQualitygoods and Intl.Outdoors, so I wouldn't recommend them either. I'd go with Illumination Supply - I've had good service from them before and they're highly recommended. Oh, and you'll need a 20mm star and file down the corners to make it fit.

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    So much to learn... Any XM-L bin would work? It sounds like voltage isn't a consideration?

    Thank you for your help.

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    yep, pretty much any LED on a 20mm star would work (XP-G2 would be interesting) as LEDs are all constant current devices. The minewt driver puts out 1A, so scanning Cree's data sheets (or using its LED comparison thingy) should give you an idea about relative light output. The main difference between them at that current is beam pattern (bigger LED die = floodier beam) and to a lesser extent, voltage (which determines runtime). It's only as current rises a lot above 1A that the differences between LED families becomes more noticeable.

    The ones I've done for friends cam out really well, with much broader less spotty beams. They all use them as bar lights. If you want yours for a helmet light, the smaller die XP-G2 might be a better thrower.

    I'd still recommend a neutral white (<5000K) tint though, the definition and contrast is waaay better.

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    I definitely want to use it as a bar (wide beam) light. Do you have any experience opening the battery pack on this model? I was trying to find a non-destructive way to look inside.

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    I've opened one up very destructively (plastic dremel cutting wheel), although you may have some more success freezing it then trying to crack the plastic weld with some leverage. I have one to do sometime over the next few weeks, so I'll give it a go too.

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    I got it open. I put the battery pack in my vice and (very) slowly increased pressure until I heard the plastic pop. It broke loose on one end and I was able to open it up enough to gently pry the rest open. There's plenty of tab left for me tor re-glue it later.

    I really wanted to see if there would be enough room for me to put in a new driver along with a couple of upgraded cells. It appears that is the case. I'd have to figure out how to rig up a weather resistant push button (the existing is a SMT on the driver/charger board) and a dedicated port for charging.

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    neat, it'll be interesting to see what you come up with!

    The switch problem can be solved with a panel mount waterproof switch - judco do a bunch of different ones that you can buy rubber boots for and there are also a range of MOM switches with STAT LEDs for a bit more. What driver are you planning on using?

    If you're going to use an Lflex or a AMC7135 based board (like the Kaidomain V2 one) you can wire the cells in parallel (currently in series) and use an NR plug soldered to a simple 18650 charger from DX/ KD. I think I might have one somewhere from a light I fixed - let me know and I'll have a look around for it.

  28. #28
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    oh, forgot to say, I wouldn't go higher than 1.5-2A as the housings on those things are pretty tiny. If you go the AMC route, a KD V2 4xAMC7135 would put out 1.1A, so a 6x board (~1.8A) would probably be just about ideal. Medium on those boards with an XM-L would correspond to high on your current set up. High would be ~3x the light.

    those drivers are cheap as chips too, about $5. Gives you more money to spend on some quality Panasonic cells

  29. #29
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    Excellent information, thank you. I've been spending a lot of time reading through this forum and other lighting related websites....

    It looks like the existing battery pack has two CGR18650CG (MH12210) 2200mAh unprotected cells in series as you stated. Is it safe to re-use these cells?

    I also have six Sanyo 2600mAh (red packaging / green insulator ring) unprotected cells I salvaged from an almost new laptop battery pack. I wasn't sure if I would use these as replacements for the 2200mAh (in the event I re-used the existing driver) or not.

    I want to keep the cost as low as possible on this retrofit. I haven't bought anything and am still "planning my attack". If my planned cost exceed 75% of a new knock-off light then I'll consider throwing my money the other direction...

    I went by my favorite electronic parts shop yesterday and noted several switches that had boot options available for them. I'll do some internet spelunking next.

    What's an "NR plug"?

    I think I will go ahead and order the XM-L 20mm stars. I plan on buying three of them (one for this project and two for my Cateye Doubleshot which will go onto the operating table next). I've been looking around and can only find the cool and warm varieties of the T6 and the cool variety of the U2. Do you know of anyone currently offering a 20mm star neutral white T6?

  30. #30
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    as long as the original cells still have most of their capacity, you can re-use them. Or, if the Sanyo cells have a higher measured capacity (not starting capacity) then use those for a bit more run time.

    NR plug = NiteRider plug, the plug at the end of the light cable or charger cable that plugs into the battery. It's a proprietary 3 pin plug that you have to get from NiteRider.

    Chinaqualitygoods and Intl.Outdoors offer NW T6, but I wasn't impressed with the quality from either. Illumination supply has a NW T5. Just search around, you may find others. I

    I did a Doubleshot a while back - just heat the head up very hot by leaving it switched on before trying to remove the faceplate screws or the ones holding down the LEDs, otherwise one or more of them will strip. You can also play with the trimpot (little white screw) in the driver to get a bit more current out of it. I managed to increase it from 700 to 900mA, which helps.

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    I may just go ahead and order three 6500k XM-L T6 stars. If I want to change the color I can always do that later. Gotta start somewhere, right?

    I like the simplicity of the 6xAMC7135. Would it require any type of heat-sink if I were running one of the XM-L T6 with a 1S2P battery pack?

    I have been looking over the documentation for the lflex driver, also. It would be nice to control everything from the momentary switch (not requiring another switch to kill battery power to the driver to turn off the light). If I were to use an lflex driving an XM-L T6 with a 1S2P battery pack @ 2000mAh, how hot would that thing get?

    Thank you for the tip on the Cateye. I'll make sure I warm it up good before trying to disassemble.

    EDIT: I remember reading the post about the trim pot on the Cateye. The existing NiMH battery pack is on its last leg. I'm not going to invest in a new NiMH battery pack. If I upgrade it to Li-ION I'll replace the driver and LEDs at the same time. Just do it up right.

  32. #32
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    sure, it's not like they're expensive either. Try LED DNA, they had some for a good price and the 2 I bought from there were fine. You can get them even cheaper elsewhere if you look around (I remember Dinodirect selling them for ~$4!).

    Easiest way to work out heat in the lflex is Vbatt-Vf x current. So on a fresh charge, the battery will sag to ~3.8V under load and the LED will be between 3 and 3.2V. So between 1.2 and 1.6W. No idea if it would be happy with dissipating that without a heatpath for extended periods though, ask George. The AMC boards don't really need heatsinking as each chip only dissipates a small amount of heat (instead of 1 chip with all the heat on the Lflex).

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    OK, I'm stressing out a bit now. I'm exploring my charger options and I'm feeling a bit overwhelmed.

    I plan on building a 1S2P pack for this light and a 2S2P pack for the other light in the near future. Can you recommend a decent smart charger that would handle both the 3.7 and 7.4 (2P) packs?

    EDIT: After some more research I think I'll just use individual cells and holders. That way I can charge each cell separately and (re)use them for other stuff also...
    Last edited by marpilli; 10-16-2012 at 10:47 PM.

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    that's one option. The other is to have both packs wired 1P and wire the LEDs in the Doubleshot in parallel (1 3A driver = 1.5A per LED). Then buy a 2 bay 18650 (independent channels) from DX and wire the appropriate plug for each pack to the terminals, so you can charge both packs at once. That'll also allow you to use a simple AMC driver for the doubleshot (they don't like voltages above 6V).

    Actually, you can do both if you want. That way you can charge/ use the cells individually or charge them as a pack, which, believe me, is much more convenient

    Holders you can get off Digikey, they're pretty cheap.

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    Hey, I'm liking that idea. Just to ensure I understand (hope my terminology is correct)...

    I could build my two packs:
    * One 1S2P for my MiNewt
    * One 1S4P for my Cateye

    Buy one of the DX dual (independent) channel chargers and add appropriate connectors to charge the packs.

    Use one of the 3000ma drivers in the Cateye but wire the XM-Ls in parallel.

    Correct?

  36. #36
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    yep, pretty much

    here are some pics of a DX charger I modified for my brother



  37. #37
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    Good deal. I think I have enough information and I'm headed down the rabbit hole.

    I put in an order with KD last night, a small order with DX this morning, and will be making a small purchase via eBay tonight. Once that stuff arrives, I'll pick up the remaining bits from the local electronics shop.

    Thank you very much for your help on this.

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    you're welcome! I'm looking forward to the results already

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    I received my KD order yesterday (drivers and XMLs). Still waiting on the DX order (charger and explosion bag ).

    The drivers are so much smaller than I expected. I'll need to sharpen the tip of one of my pencil irons so I won't butcher this thing when I get to hooking it up.

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