Wuben        
Results 1 to 5 of 5

Thread: Question about H17F + primaries

  1. #1

    Default Question about H17F + primaries

    Sorry if this isn't the right place to ask but after some searching I didn't find the info I'm looking for.

    I have a light with the H17F (or H17Fx, I don't actually know) driver and its behavior with a primary battery isn't what I expected. Low mode is ~1 lumen, medium is ~20 at the most. According to what I've read about the driver, it sounds like a primary should at least power the light on low and medium. That would be sufficient in an emergency if I didn't have an 18350 handy.

    Here's what I don't understand: When testing a primary, the light doesn't come on at the low setting. From off, click and nothing happens. But click again and it lights up at the medium setting. It will try to sustain the next setting up but runs out of steam right away. That's fine, I'm only interested in knowing that it will function on low and medium, as that's enough in an emergency. The failure to illuminate at 1 lumen doesn't make sense to me. Could someone please help me understand why a primary isn't able to power this driver at what seems to be a very doable level? Tested several primaries, by the way, all new out of the package and from a couple of different (reputable) manufacturers. Same behavior with all of them.

  2. #2

    Default Re: Question about H17F + primaries

    I've not seen that behavior, pretty odd. Do you have an 18350 to narrow the variables?
    Maybe the CR123 isn't putting out enough amps to properly drive the circuit? That's the only thing that stands out initially for me
    Have torch, will travel.

  3. #3
    Flashaholic*
    Join Date
    Dec 2011
    Location
    NJ
    Posts
    1,650

    Default Re: Question about H17F + primaries

    What LED? Keep in mind that the 7135 regulators the driver uses add a tiny bit of voltage overhead and they are linear regulators so not enough voltage could very well be the issue.

  4. #4

    Default Re: Question about H17F + primaries

    It's in a triple with 3 x 219C emitters. When I use Keeppower 18350 rechargeables during normal use, the light works as expected.

    If too little voltage on low is the problem, I can try setting up a second mode group with a higher low. What do you think the max lumens are that this driver can support on a primary? Fifty? Eighty? If I could have a mode group with just 2 levels, both above a couple of lumens but below whatever is too much, that would be a reasonable workaround in an unexpected situation where I don't have an 18350 available.

    Thanks very much for the help.

  5. #5
    Flashaholic*
    Join Date
    Dec 2011
    Location
    NJ
    Posts
    1,650

    Default Re: Question about H17F + primaries

    Your best is to just carry a different light in a situation like that. What you are asking for is opposite to how it works. If you ask to run an LED harder two things happen at the same time: the voltage needed to run the LED increases and the voltage of the cell sags. In short, the harder you ask to run the LED the worse it actually gets for you.

    The only thing I can think of for extreme emergencies is to switch it to max as the FET (turbo) has a ton less voltage overhead and might run it brighter but unregulated CR123 is also a terrible idea so just use lithium ions for that driver.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •