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Thread: Requirements of cavers are different

  1. #1
    Flashaholic Tobias Bossert's Avatar
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    Default Requirements of cavers are different

    This thread is for caving LED lights, since the requirements of cavers seem to differ highly from most threads in CPF.

    Most CPF members seem interested in maximum peak light output out of a minimum space and weight. Many modifications of professional flashlights discussed here result in very high light flux with the price of short burn time. Almost all flashlights DIY mentioned in CPF are specialized on these requirements.

    My hobby is exploring large caves, where iím used to stay for two to five days continuously. Cavers used carbide lights so far. Now batteries and LEDs are advanced enough to be used as a primary light source. There are many headlamps on the market, professionally produced and acceptable in price. But most of them are far away from being optimized for caving needs!
    Cavers need three different lightning modes:
    • Spotlight with high flux in a narrow beam to be used for short time only (some minutes)
    • Working light for about 8 hours a day, LED without optics, aim is 100 lm constant
    • Reserve light for another 8 hours a day, LED without optic, 10 lm is strong enough
    All these requirements can be covered with single rechargeable LI-Ion cells and linear current regulators (like AMC 7135) dimmed by pulse width modulation (like PIC12F269): Very cheap professional multi level boards having a very good efficiency are available. Efficiency is good, because voltage level of rechargeable LI-Ion cells are a little bit higher than the voltage of white LED only. The same is true for three primary LI-Fe cells in series.

    I use a SSC P4 USVNI with a mobdar (Gaggione LL3) as short time spotlight with a single level 16mm board bearing two AMC7135. The working light is a SSC P4 S2SJ1H without optics with a three level 16mm board bearing one AMC7135 and a PIC12F269. Using one single rechargeable Li-Ion 18650 (2200mAh) this working light is constant 350mA over a period of about 6 hours under cave conditions. Two such cells in parallel hold all over one caving day generously. With three primary Li-Fe AA cells (2900mAh) in series it holds over one caving day only just.

    The problem seems to be solved so far, but...
    Many cavers donít like to use exotic cells for caving proprietarily. They prefer to use AA alkaline or NiMH as they are used with most other devices. Unfortunately voltage levels of alkaline and NiMH batteries mismatch to Vf of white LED.

    The average temperature in our alpine caves (Austria, Germany, Swizerland) is 0 to 5įC. Under such conditions 3 AA alkaline or normal NiMH cells fall short and 4 cells in series are needed at least. But with 4 cells efficiency of linear regulation is poor, because average input voltage is much too high. Additionally heating is inacceptable, especially when you newly enter the cave with fully charged or fresh batteries being still worm from outside.

    4 NiMH provide still sufficiently low voltage drop under cave temperatures to be discharged completely, but 4 alkaline drop below 3,6V long before being empty. Under cave conditions you will need 5 or 6 alkaline in series, otherwise you will have to replace them still half full. Therefore a step down converter is needed.

    For the spotlight no multilevel is required. Shoppe SOB750, Kai SKU2982 or DX SKU3256 / 4255 may be applicable for example.
    But as far as I can see, no multilevel low power step down converter board is on the market at the moment, serving for our work / reserve light reasonably. Iím not willing to develop a new board by my own, since few devices will be needed only.

    Does anyone know a multi level step down board with appropriate specifications?
    Vin = 3V to at least 9 V
    Iout = about 350mA switchable to about or even below 35mA with reasonable efficiency
    Vout = 3,0 to 3,5V
    Is there any other caver in CPF home building or modifying cavers LED-headlamps?

    Kind regards
    Tobias

  2. #2

    Default Re: Requirements of cavers are different

    Hi Tobias, welcome to CPF! Yes there are several cavers here (I'm not one myself), there is some discussion of caving lamps, and I think some modders have made their own (I haven't paid close attention though).

    I'm surprised you want 100 lumens as a regular light, as I thought cavers usually use much less than that. To get 100 lumens out the front of a light with today's best leds, you probably need around 2 watts of battery power. So 8 hrs/day*5 days*2 watts = 80 WH, which would be 18 or so of those expensive lithium AA's, or maybe 30 alkaline AA's. I hope you won't use so many disposable batteries, for environmental reasons among other things. And managing that many cells sounds like a nuisance anyway. You might consider D sized nimh cells (12000 mAH so you'd need around six of them) or a lithium ion pack. I don't know why lights like the Stenlight with external packs don't use camcorder batteries. A Sony NP-F970 pack is quite compact (has six 18650's inside), powerful (7.4 volts 6000 mAH= 44 WH, so you'd need just two of them) and relatively inexpensive (around 25 USD on ebay if you don't mind the no-brand ones).

    As for stepdown boards, the STFU board used in the Spy 005 might do what you need, but I'm not sure it has enough input voltage range. You could ask dat2zip (the designer) about it. You might also look at some of dat2zip's other threads in this section about boards that he's made or is making. I know he's looking for suggestions and your idea sounds like a good one.

  3. #3
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    Default Re: Requirements of cavers are different

    By coincidence, I've just got back from a trip down White Scar near Ingleton, UK. Not very long but it did involve some swimming while twisting our heads to keep them above water!

    Most of us were using Petzl Spelios:
    http://en.petzl.com/petzl/LampesProd...57&Produit=495

    However, Jimmy had a homemade lamp. I think he used a cheap LED array from the far east coupled with a Petzl waterproof 4xAA battery holder and his own PIC controller. As well as offering multiple power levels it could, at the flick of a switch, flash out the actual run time in morse code! This is very useful for estimating the remaining battery capacity.

  4. #4
    Flashaholic* TorchBoy's Avatar
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    Default Re: Requirements of cavers are different

    Yay, another caving thread.

    I went for a short caving trip (1 hr 45 min) while camping last week. One particular too-tight squeeze - which I decided was quite enough for one day just by itself - was followed soon after by a small drop where I found myself partly hanging by my helmet in a front-to-back wedging between two rock faces. Perhaps not unexpectedly that managed to kill my home-made light on the front of the helmet, so I had to resort to my home-made hand torch to get out.

    I haven't looked yet to see if the K2 LED was just shorted out or if a connection came loose. I wanted something brighter and more versatile anyway, so time for a redesign.
    No, a torch does not always mean flames.
    Ian.
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  5. #5
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    Default Re: Requirements of cavers are different

    Quote Originally Posted by paulr View Post
    for environmental reasons among other things.
    Oh please. For environmental reasons, please turn your computer off and recycle all your lights and batteries. And I hope you don't own a car or live in a house made of wood... I could go on.

  6. #6

    Default Re: Requirements of cavers are different

    Quote Originally Posted by KingGlamis View Post
    Oh please. For environmental reasons, please turn your computer off and recycle all your lights and batteries. And I hope you don't own a car or live in a house made of wood... I could go on.
    KG, I do recycle batteries, but re-using them over and over by recharging is even more effective since it means you're not buying as many in the first place. I live in a big apartment building, which means energy consumption per person something like 1/4 that of single family houses because of centralized heating and stuff like that. I haven't brought myself to get rid of my car (I really should), but it has 35k miles after 8+ years (1998 Civic DX) since I'm generally able to get around by public transit or walking (of course I'd really like a solar powered car like Darrell's). Spent batteries are a significant environmental problem and it's actually illegal in California to throw them away instead of recycling them.

    There is only one earth that we live on and if we mess it up too much, it can't take care of us any longer and we are done for.

  7. #7
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    Default Re: Requirements of cavers are different

    Quote Originally Posted by paulr View Post
    KG, I do recycle batteries, but re-using them over and over by recharging is even more effective since it means you're not buying as many in the first place. I live in a big apartment building, which means energy consumption per person something like 1/4 that of single family houses because of centralized heating and stuff like that. I haven't brought myself to get rid of my car (I really should), but it has 35k miles after 8+ years (1998 Civic DX) since I'm generally able to get around by public transit or walking (of course I'd really like a solar powered car like Darrell's). Spent batteries are a significant environmental problem and it's actually illegal in California to throw them away instead of recycling them.

    There is only one earth that we live on and if we mess it up too much, it can't take care of us any longer and we are done for.
    While I don't mean to offend you or derail this topic any further, I must respond. You, like it or not, are an environmental hypocrite. Which is OK with me, as I live in the real world, not the fake enviro wacko world. All enviro wackos are hypocrites. But again, that is another topic. Feel free to start a new topic stating why you think I am wrong and I will provide unending proof of why YOU are wrong.

  8. #8

    Default Re: Requirements of cavers are different

    KG, I assure you that I will give your opinions on those subjects all the consideration that they deserve.

  9. #9
    Flashaholic* TorchBoy's Avatar
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    Default Re: Requirements of cavers are different

    Hey, if you guys don't mind taking the greenie-bashing elsewhere... Back to caving?

    The use of carbide in caves in this country is deprecated (see #7) because of environmental reasons. LEDs are "cooler" anyway.

    Anyway, I've just taken a look inside my headlamp to see what went wrong. I was surprised to find a home-made driver circuit that predates the release of the various AMC7135 boards on DX and KD. Time to upgrade that, perhaps. As for what went wrong, the only obvious contender is a couple of resister leads that may have touched each other. It works fine now.

    But wait! I put the front cover back on and it stopped working again. One of the wires to the K2 itself has come adrift, pulling the track off the K2 board. Mutter.
    No, a torch does not always mean flames.
    Ian.
    LED Driver List - now database driven and with new search features.

  10. #10
    Flashaholic*
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    Default Re: Requirements of cavers are different

    Hi Tobias, welcome to CPF. Check out the "Headlamps" forum here for some other caving threads. There are a few members here who design and make headlamps specially for caving and/or diving. Barbarain is one.

    That 0 to +5 degree C range is difficult. I know when I'm winter camping that is a difficult range to be in because things are wetter than if the temp is a bit lower and the water is snow or ice that can be removed before it soaks into clothing and equipment.

    Paulr: cavers usually can get by with less than 100 lumens, but in BIG rooms it can be hard to get enough lumens. This also depends on the color / reflectivity of the rock/earth, and what you are looking for. I've also noticed that some people just need more lumens.

  11. #11
    Flashaholic* uk_caver's Avatar
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    Default Re: Requirements of cavers are different

    Personally, I haven't found the near-zero range to be too bad for alkaline batteries, at least when pulling modest currents out of them (<400mA out of 6Ah cells, typically nearer 100-200mA).

    When caving in Slovenia, where the mountain caves are often only just above freezing, 3-cell alkaline packs seem to work fine for running LED lights using linear regulators.
    Judging battery condition by comparing light levels (eg "Is there the proper visible difference between high and medium power?"), the batteries seem to last about as long as would be expected before their output falls below the level needed for full output.

  12. #12

    Default Re: Requirements of cavers are different

    The STFu board does meet your requirements. It is also very efficient. It is however not small.


    Cheers
    Dave

  13. #13
    Flashaholic* TorchBoy's Avatar
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    Default Re: Requirements of cavers are different

    Who's the CEO of the Stuff You board?
    No, a torch does not always mean flames.
    Ian.
    LED Driver List - now database driven and with new search features.

  14. #14
    Flashaholic Tobias Bossert's Avatar
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    Default Re: Requirements of cavers are different

    Quote Originally Posted by Data View Post
    The STFu board does meet your requirements. It is also very efficient. It is however not small.
    Cheers
    Dave

    Hello Dave,
    thanks for your hint to "STFu board". Mechanical size is no matter for me, since I plan to integrate the converter board into the battery housing worn in the chest pocket rather than into the LED-housings mounted on the helmet (two separate, one for beam and one for wide).
    On CPF I can find many posts mentioning this board in the context of a specific flashlight, it seemes to be a good solution, as far as I can see.
    I'm not able to find descriptions or specifications for this board and where to buy it separately.
    Can you give me the missing links please?
    Thanks
    Tobias

    I tried to send you an email directly to 'spy005@comcast.net', but it was returned by your spamfilter.
    My email is
    Tobias@Bossert-inet.de

  15. #15

    Default Re: Requirements of cavers are different

    Quote Originally Posted by Tobias Bossert View Post
    Hello Dave,
    thanks for your hint to "STFu board". Mechanical size is no matter for me, since I plan to integrate the converter board into the battery housing worn in the chest pocket rather than into the LED-housings mounted on the helmet (two separate, one for beam and one for wide).
    On CPF I can find many posts mentioning this board in the context of a specific flashlight, it seemes to be a good solution, as far as I can see.
    I'm not able to find descriptions or specifications for this board and where to buy it separately.
    Can you give me the missing links please?
    Thanks
    Tobias

    I tried to send you an email directly to 'spy005@comcast.net', but it was returned by your spamfilter.
    My email is
    Tobias@Bossert-inet.de
    I am sorry you can't email me to comcast. I do not know why. They are a pain sometimes but I have no choice.

    Tobias, the STFu was designed by dat2zip just for the SPY and I did the programming in it. It is too big to fit in a E2E-size light so we have not tried to offer it. It requires two primary CR-123 cells or anything with higher voltage. It's a high end board and priced at $75 without a switch. You could not use the switch we normally use anyway as it has no knob only a screwdriver slot. Any 7 (or more) position rotary switch would work just fine but you have to be handy with a soldering gun to run jumpers from the board to what ever switch you choose. This thread has more detailed info about the STFu.

    If you are interested let me know and I will talk to dat2zip about putting it in the shop.


    EDIT: more detail on STFu

    Cheers
    Dave
    Last edited by Data; 10-30-2007 at 10:04 AM.

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