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Thread: Help modding dive light

  1. #1

    Default Help modding dive light

    This is my first post on this cool site.
    I purchased a Tovatec Dive light with 3 "C" LED cell dive light a few years ago and now I want to mod it with 2 - 26650's.
    I soldered the new 12volt led in and tested the light buy jumpering the tail of the light with the battery and its real bright now, I estimate about 4000 LM.
    The problem I have is the tail cap switch ( which was push low, push high, push off) does not work.
    I get a real quick dim flash when I push the button, then nothing.
    I need some real help with this as I am at a loss.
    Thanks

  2. #2
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    Default Re: Help modding dive light

    Hi straycat, and welcome to the forum!

    I also love the 26650. Having built and modified several dive lights as well as many non-diving LED lights, I think I'm probably qualified to at least enter the conversation, and I'm only one of many.

    Switching from 3xC to 2x26650 should be more complicated than switching out the LED and batteries. 3xC would pretty much direct drive an older LED, meaning you might just have a FET driver. If you are going to mod lights then direct drive, FET drive, and drivers are concepts you should understand; there's a lot of info about that on this forum but it can be pretty hard to penetrate. We can discuss it here if you want to.

    2x26650 could work with a FET driver and 6V LED, but not with a 12V LED. Also, bypassing the driver might produce pretty impressive results, but again with a 6V LED, not a 12V LED.

    I really doubt that this light has a driver that can take 3xC and produce unimpressive output, then take 2x26650 and produce impressive output, so there are some mysteries here to resolve.

    First things first, are you sure you have a 12V LED? There are some LEDs that are 6 or 12V, depending on how you wire them, and there are some boards that can be switched from 6V to 12V configuration for these LEDs. It might help if you posted what LED and board you have.

    As far as why you only get a flash when you use the tailswitch, that could easily be the driver sensing an overload and shutting down to protect itself and everything else.

    If you're sensing a lot of equivocation here, that's intentional. We really need to get a better idea of what you have and what you have tested. It's not clear what you mean when you say 'jumpering the tail of the light with the battery', and that's pretty important.

    Let's keep the conversation going, and hopefully we can help you sort out what you need to do!

  3. #3

    Default Re: Help modding dive light

    I got the led from a buddy , he said he believed it was a 12 volt led That he took out of a Harbor freight led light. We tested this led in his light with his power supply ( before we removed it to be installed in the dive light) and it did not come on til 4.8 volts and was bright at 6 volts 1.2 amps all the way up to 12 volts 1.7 amps. So installed it in the dive light with the original driver from the dive light 3 x "C", but the tailcap switch would not work so we ran a wire from the negative of the last 26650 to the outside shell of the dive light and checked the brightness. It was good. We only ran it for 30 seconds, still wondering if the driver would toast.
    Dive switch does not work??

  4. #4

    Default Re: Help modding dive light

    Quote Originally Posted by straycat View Post
    I got the led from a buddy , he said he believed it was a 12 volt led That he took out of a Harbor freight led light. We tested this led in his light with his power supply ( before we removed it to be installed in the dive light) and it did not come on til 4.8 volts and was bright at 6 volts 1.2 amps all the way up to 12 volts 1.7 amps. So installed it in the dive light with the original driver from the dive light 3 x "C", but the tailcap switch would not work so we ran a wire from the negative of the last 26650 to the outside shell of the dive light and checked the brightness. It was good. We only ran it for 30 seconds, still wondering if the driver would toast.
    Dive switch does not work??
    First: Do you know that LEDs are polarized devices? They require that their power flow in one specific direction. They have a positive terminal and a negative terminal. Are you sure that you have everything wired up correctly? Also, are you certain that the 26650 cells were BOTH fully charged? The switch on the original 3xC cell light is likely using a resistor to make a low mode but there could be other components involved as well.

    Ultimately, a picture is worth a thousand words. If you could post some pictures to an external hosting site and then link them here, it would help.

  5. #5

    Default Re: Help modding dive light

    Battery's full charge, I believe its wired correctly as The light works when we ran a wire from the negative of the last 26650 to the outside shell of the dive light and checked the brightness. It was good I estimate 4000 LM.

    https://drive.google.com/file/d/1-f7CSMCW1IDoqHsdZ_9WiB5jXaT3-3Nn/view?usp=sharing, https://drive.google.com/file/d/19TM...ew?usp=sharing, https://drive.google.com/file/d/1C_0...ew?usp=sharing, https://drive.google.com/file/d/1HmV...ew?usp=sharing, https://drive.google.com/file/d/1gii...ew?usp=sharing

    https://drive.google.com/file/d/1-f7...ew?usp=sharing, https://drive.google.com/file/d/19TM...ew?usp=sharing, https://drive.google.com/file/d/1C_0...ew?usp=sharing, https://drive.google.com/file/d/1HmV...ew?usp=sharing, https://drive.google.com/file/d/1gii...ew?usp=sharing
    Last edited by straycat; 01-06-2021 at 03:13 PM. Reason: adding url for pictures

  6. #6
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    Default Re: Help modding dive light

    Your URLs require permission to view. I cannot see any of the pictures.

  7. #7

    Default Re: Help modding dive light

    I believe they are reviewing them now

  8. #8

    Default Re: Help modding dive light

    When I click on them they work???

  9. #9
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    Default Re: Help modding dive light

    That's because you have access. When I click on the link, a page comes up that says "you need access". There's a box to type a message (presumably to the granter of access, which I presume is you), and a button to click to request access. There's also a big lock symbol. It's a google drive permission issue, not with the forum.

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  11. #11
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    Default Re: Help modding dive light

    Okay, that works!

    In one of the pictures you posted the board says it should be a Cree XM-L LED on it. That's an older LED at this point, and typically runs 3.0-3.5V depending on how hard you push it. The datasheet says 2.9 typical at 700 mA, but I was seeing higher than that. It runs 3.3-3.5V at 3A.

    Is that the LED from the Tovatec or from the HFT light? If it's from the HFT, it's probably a knock-off.
    Last edited by DIWdiver; 01-12-2021 at 08:00 PM.

  12. #12

    Default Re: Help modding dive light

    Quote Originally Posted by DIWdiver View Post
    Okay, that works!

    In one of the pictures you posted the board says it should be a Cree XM-L LED on it. That's an older LED at this point, and typically runs 3.0-3.5V depending on how hard you push it. The datasheet says 2.9 typical at 700 mA, but I was seeing higher than that. It runs 3.3-3.5V at 3A.

    Is that the LED from the Tovatec or from the HFT light? If it's from the HFT, it's probably a knock-off.
    That LED is from the dive light and it burned out when I applied 8 volts to it

  13. #13

    Sigh Re: Help modding dive light

    Quote Originally Posted by straycat View Post
    That LED is from the dive light and it burned out when I applied 8 volts to it

    I guess this problem is too difficult to resolve??

  14. #14
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    Default Re: Help modding dive light

    Apparently there's nobody reading this who knows the innards of that particular light, and you haven't disassembled it far enough for us to see what we need to see. Or if you have, you haven't posted pictures.

    For example, does the tailcap hold nothing but a switch, or is there a driver in there, or maybe just a PTC self-resetting fuse? What does the inside of the head look like? How much room is there for a driver? What does the heatsinking look like? What size is the MCPCB (that's the board the LED is mounted on; I'm assuming it's aluminum, not fiberglass).

    Is there an IMG_1016? I think you double-posted IMG_1017.

    What is the model of the light? I thought I had that before, but I can't find it now.

    You might consider asking a moderator to move the thread to the Dive Lighting subforum of the Special Application Lighting forum. You are more likely to find someone there who is familiar with this particular light.

  15. #15

    Default Re: Help modding dive light

    Ok, Lets go a different direction. Original light was rated for 800 lumens Use 1× 26650 battery, original tailswitch (which still works ,low, high, off), a spacer for length rq’d to make up the difference between 3 “C” cells and 1 -26650 battery. What led would you use to increase the light output?

  16. #16
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    Default Re: Help modding dive light

    In general, you get more light by pushing higher current. If the light has a proper LED driver in it, that will supply (or at least attempt to) the same current no matter what LED you install.

    Newer LEDs might have a slightly higher output at the same current, but they run at lower voltage. That might extend your run time somewhat. Or not, depending on the driver. I don't think you are going to get a noticeable improvement in brightness by just changing the LED. For that you want a higher current driver.

  17. #17

    Default Re: Help modding dive light

    How do I know what the current capabilities are of my driver?

  18. #18
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    Default Re: Help modding dive light

    There are a couple of ways. All involve having either a digital multimeter (DMM) with DC current settings, or a power supply with a current reading. If you don't have a DMM, you can get one as cheap as $4 at Harbor Freight. At that price its only a little better than a toy, but it should get you close enough for what you need.

    Unfortunately, for all of these, you need a working LED, so you'll need to either fix yours or get a similar one. If the currents are up above a hundred milliAmps, you'll need the LED to be on an MCPCB, which you probably want anyway. If above a few hundred milliAmps, you'll need that MCPCB to be mounted on a heatsink. During the testing you'll need to pay attention to the current and the LED temperature to avoid frying the LED. If you start low and increase slowly, you can keep everything safe. If not... well, I have fried a $50 LED in about the time it takes to blink. It literally looked like a camera strobe.

    The way to stay safe is: start with the supply voltage below the LED voltage (or within the known safe voltages for your setup), increase slowly, monitor LED temps (I use a finger for this, no high-tech).

    1. Connect the meter in series between the back of the batteries and the spring on the tailcap. Obviously you have to remove the tailcap for this, and somehow make all the connections. This measures the battery current. It's also often referred to as the tailcap current, as it is the current that passes through the switching mechanism in the tailcap, which can easily be the limiting factor in a design. In this light the LED current would be the same as or a bit higher than the tailcap current.

    2. Place a power supply in place of the batteries. Same connection issues as above. Start with the voltage around 3V. Increase the voltage slowly to 4.5 volts. Stop if the current reaches 3A (max rating for the XML). If the current stops going up, you can stop there. This also measures the battery/tailcap current. But this test can also tell you what type of driver you have. If the current stops going up and remains constant, you have a linear driver. If the current actually starts coming down as the voltage goes up, you have a buck type switching driver. In either case, the peak current is probably very close to the LED current.

    3. Since you have already unsoldered the LED board, you probably won't mind actually putting the meter in series with the LED. This would measure the actual LED current. If you use batteries, you get the current at one particular battery voltage. Doing the test with the power supply instead can give you a lot more information. Or you can run the batteries down and get the same data. It just takes longer.

    Keep in mind that a DMM in current mode will introduce an additional resistance to the circuit. This can affect the behavior of the circuit. In some cases this is trivial, but given the high currents and low voltages we're talking about, it can be quite significant. We can talk more about this later if it comes up.

  19. #19

  20. #20

    Default Re: Help modding dive light

    Here's some pics of the internals of the dive light.
    After reviewing these can I use a brighter LED with 1×26650 with the existing light, driver and switch and about how much brighter will it be if I do this?
    This is the original LED that burned out with 2x26650's https://drive.google.com/file/d/1Rqb...ew?usp=sharing
    https://drive.google.com/file/d/1C9O...ew?usp=sharing

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  22. #22
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    Default Re: Help modding dive light

    Okay, now we're getting somewhere. I'm going to guess that the driver is a FET driver. I see no inductor or current sense resistor, and it's definitely not a '7135 driver (pinout is wrong). The part marked 11N06 looks like a PHT11N06 FET, and the part of the circuit that I can see is consistent with this. This is the part that might be mistaken for a '7135, but it's definitely not that.

    If correct, what this means is that the LED current is determined by all kinds of factors throughout the light. The voltage of the battery, Vf of the LED, resistance of everything in the circuit (battery, switch, wiring, LED, FET, connections) all factor into the current. And the current determines the brightness.

    Running a light like this on 2 LiIon Cells in series would be insane. If it didn't instantly fry the driver, it would cause currents massively higher than the light is designed for. It would be a race to see what component failed first. If the driver sensed the overvoltage and shut down (causing brief flash on the LED), and still survived the high voltage, then kudos to the designers for surviving a potentially catastrophic situation.

    In general I would say a FET driver designed for alkaline cells (high resistance) and older LEDs (higher Vf) is probably unsuitable for use with modern LiIon cells (low resistance) and LEDs (low Vf). Both of these upgrades could significantly increase LED current and lead to rapid overheating. However, if you have it working with a 26650 and what I'm guessing is an older LED, and it doesn't seem to be very bright, and especially if it doesn't seem to be getting hot very quickly, you could probably upgrade to a newer LED with lower Vf. This would increase current, light, and heat. It could be quite a dramatic increase, but it's hard to know for sure.

    The XML3 compared to the XML has about 0.2V lower Vf at various currents. Since small changes in Vf can result in large changes in current (which is the whole reason we shy away from FET drivers and tend toward CC drivers), this might be enough of an upgrade for you.

    That would be my first attempt - replace XML with XML3. If I could make some measurements, I might make a different recommendation, but with the information we have, that's what I would suggest.

  23. #23

    Default Re: Help modding dive light

    As I am new to this modding, where can I purchase one of the XML3 preferably MCPCB and exactly what is the part #.
    3,6,12,volt?
    My existing led MCPCB is 23.2 mm

  24. #24
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    Default Re: Help modding dive light

    The bare emitter you can get lots of places. I would probably go to Digikey, maybe Mouser.

    I'm no expert on buying emitters mounted on MCPCB, but there are a number of places that sell them - Mountain Electronics and LEDSupply come to mind.

  25. #25

    Default Re: Help modding dive light

    I purchase a XML3 on mcpcb.
    What voltage do I need and any other specs I should be concerned with?

  26. #26
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    Default Re: Help modding dive light

    I believe the XML3 only comes in 3V version. Make sure you get the color temp and bin that you want. Make sure the MCPCB will fit your light. I think that's about it.

  27. #27

    Default Re: Help modding dive light

    Whats a BIN?

  28. #28
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    Default Re: Help modding dive light

    After they build the LEDs, they test them and sort them into 'bins' (probably not literally) by luminous efficacy. Bins with the higher efficacy will be more expensive. It's usually not a dramatic difference, but it can be more than a little bit. Back in the day when I was building lights, the highest XML bin was U2. R2 was a pretty poor bin.

  29. #29

    Default Re: Help modding dive light

    So how do they grade the bins?
    I there any logic to it, like 1 is worst than 10 best ?
    From your comparison seems like U2 is very good so would U20 be really bad?
    Where's the R come in?

  30. #30
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    Default Re: Help modding dive light

    You have to read the datasheets to find out. There is some logic to it, but you have to know where to start, and what's actually available.

    Or, some vendors have enough specs on their websites that you can figure it out.

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