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Thread: possible to change a 6v headlight to 7.2v?

  1. #1

    Default possible to change a 6v headlight to 7.2v?

    i have this

    http://www.flashlightreviews.com/rev...i_hlx-712l.htm

    i quite like it but it runs on 3v cells, and my 3v cell charger is very cheesy and i cant tell if the cells are fully charged?

    any way to make this light work with 3.7v cells ? (resistor) ?

    or any other thoughts?
    If and when the the big dookie hits the fan, and global chaos ensues, i want a couple of quality AA lights within reach.

  2. #2

    Default Re: possible to change a 6v headlight to 7.2v?

    I don't have that, but since the battery voltage is higher than the LED voltage, and it's regulated, it must have either a buck converter or a linear regulator.

    If it's a buck convertor, it should run fine on higher voltage -- the biggest risk is probably overvoltage on a cap or some such, but that's fairly unlikely.

    If it's a linear regulator, it's already burning off a ton of heat -- at >7V (2x IFRs at full charge), more power is burnt in the regulator than in the LED, and this only gets worse as you run higher. I wouldn't recommend running this on higher voltage cells.

    If you can measure the tailcap current, you can easily determine which type of driver you'll dealing with: a linear regulator will draw probably 350mA or so from the battery, and keep the same current draw all the way. A buck converter will start at 200mA or so with full batteries, and the current draw will increase as the voltage drops.


    As for other thoughts, you might look into an emitter swap for an SSC P4 -- Luxeons are pretty inefficient.

  3. #3

    Default Re: possible to change a 6v headlight to 7.2v?

    hmm, all sounds rather complicated. perhaps ill just put it up on the marketplace and get a zebralight?
    If and when the the big dookie hits the fan, and global chaos ensues, i want a couple of quality AA lights within reach.

  4. #4
    Flashaholic* uk_caver's Avatar
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    Default Re: possible to change a 6v headlight to 7.2v?

    I've looked around for internal pictures, of the light, but haven't yet found any.
    I'd have thought the regulator would likely be of buck design, and like Benson said, might well be capable of dealing with a little higher voltage, unless some components were just on the edge of their abilities with the normal cells.

    However, it should be remembered that regular Li-Ion cells are only nominally 3.7V. When fully charged, they're more like 4.2V, so you'd have a maximum input voltage of 8.4V for a pair.

    As for a Zebralight, it's a seriously different beam - good for some uses, but not for others.

  5. #5

    Default Re: possible to change a 6v headlight to 7.2v?

    Quote Originally Posted by waddup View Post
    i have this

    http://www.flashlightreviews.com/rev...i_hlx-712l.htm

    i quite like it but it runs on 3v cells, and my 3v cell charger is very cheesy and i cant tell if the cells are fully charged?

    any way to make this light work with 3.7v cells ? (resistor) ?

    or any other thoughts?
    That light does not have any external heat sink for the LED.
    You could try the 16340's but they may overheat the led.
    You could also upgrade the led. SCC P4 or P5 - this will not affect the beam shape much but put out much more light...but you still have a heat problem with that design...

    PS...I have a few lights similar to this one.

  6. #6
    Flashaholic* NoFair's Avatar
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    Default Re: possible to change a 6v headlight to 7.2v?

    I seem to remember people using this with rechargeables with no problems, but I'm getting old

    If you have a power supply you could see how much current it draws when increasing the voltage. If it draws less current it should be regulated, I'd try up to about 8V and see.

  7. #7
    Flashaholic*
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    Default Re: possible to change a 6v headlight to 7.2v?

    No need to change anything, it works fine on 2 x 3.7 rechargeables. At least mine does, but proceed at your own risk. I think the biggest issue is the low voltage shutoff probably won't kick in so there might be a chance of ruining the cells if you let it run down too low.

  8. #8

    Default Re: possible to change a 6v headlight to 7.2v?

    The 6v Fenix HP10 runs just fine off the Stenlight's 7.2v battery pack

  9. #9

    Default Re: possible to change a 6v headlight to 7.2v?

    Quote Originally Posted by vanoord View Post
    The 6v Fenix HP10 runs just fine off the Stenlight's 7.2v battery pack
    That's good to know...Thanks

    I would rather have 2 Lions over 4 bunnies any day...

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