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Thread: Hotwire Dive Light (Underwater Kinetics)

  1. #1
    Flashaholic* Timson's Avatar
    Join Date
    Mar 2004
    Leeds - England

    Default Hotwire Dive Light (Underwater Kinetics)

    I have an 'Underwater Kinetics' D400R dive light (Older version of current D4R)

    The light has always proved to be very reliable and bright.

    As standard it no slouch - running an 18W lamp from a 4.8v 4000mah 4D NiCd battery pack.

    The light holds it's own very well against what most people bring diving...but when I took it on my last diving holiday to the Red sea where there was lots of the latest trick gear being used - it started to look a little bit sickly compared to the big 'Kowalski's' and the like.

    Couldn't have that....Decided that my humble UK-D400R should be the subject of my next mod....A real 'sleeper' that would surprise the hell out of the 'big guns'.

    The light has a bi-pin high temp socket as standard that takes the regular size Bi-Pin WA Lamps.
    I had a few extra WA1185's lying around and thought - What the hell...

    My concern was 'heat'.....that the reflector might not be up to the job as it is plastic.
    I emailed the manufacturers with my question and they informed me that the reflector was the same as the one that they use in their 30W version - so should be fine

    Now my problem was how to power it.

    I only had limited space. The existing 4D battery pack is arranged in a square 'brick' configuration.

    To cut a long story short I ended up running 16 x 2500Mah AA cells (2 parallel packs of 8 cells - for WA1185 spec voltage of 9,6v).

    The result was brilliant...A massive leap in performance.

    The only niggle in my mind was that the WA1185 was actually capable of so much more....but I couldn't figure how to get the required voltage / capacity into the light for a properly overdriven 1185.....UNTIL NOW

    I knew that I could squeeze in 9 x sub C cells into the light body - but knew that these high performance cells would instaflash the poor 1185 - even after days off the charger. (My cells settled to 12.6v after about 5 days!)
    Enter the Hotdriver to save the day.

    My Sub-C cells are high performance model car racing cells which have undergone a process by the maufacturer that they call 'Zapping' which is a controlled charge /discharge process designed to reduce internal resistance and raise their voltage.
    The cells are 4300Mah and are spec'd to hold over 1.2v per cell at 30A discharge!

    After clarifying a couple of things regarding the wiring of the driver - I integrated the hotdriver into the light, mounting it onto the circuit board behind the reflector...

    The hotdriver is an HP version, set at 11.1v - To really make that lamp fly.

    Shot of Hotdriver on flashlight circuit board.

    Circuit board and reflector re-united and hooked up to the battery pack

    Had a bit of a pannic with my battery pack.
    These high performance cells are just a tad bigger than the old cells I measured up - and don't fit how I intended.
    Fortunately the pack will 'just' squeeze into the body on its side.
    The un-asthetic black thing on the battery pack is a strip of motorcycle innertube which serves to make the pack a nice fit without rattles.

    Everything re-assembled and the light looks completely standard.
    A2 included for scale

    The results are AWESOME....
    Soooo much whiter and brighter. (I've never seen a whiter incan light)

    Did a comparison with my dads much newer (and standard) D4 18W lamp...and it just absolutely blows it away.

    Tried and tried to do good comparative beam shots in the garden, but couldn't get them to turn out right.....Then got completely hampered by rain.

    Took these shots indoors - which whilst not great - give a fair indication as to the relative performance difference....
    They don't really do it justice - but hey - the camera's old - and I don't know what I'm doing with it!....Wish you could see this thing outside as I can.

    Std 18W D4

    UK 400R (WA1185 - Appx 37W)

    The reflector in this model is heavily 'stippled' and is a flooder.
    I have a much smoother narrow beam reflector on order from my local dive shop...Can't wait to see how that turns out.

    I am slightly concerned about generated heat....Especially at the lens (which is plastic) - but hopefully as this lamp is really only used underwater, then the constant cooling on the lens should keep things OK.

    This really is an easy and satisfying mod....
    I'm sure there are quite a few of you out there who dive and probably own one of these lamps that may be interested in doing the same thing...Go on you know you want to.

    Last edited by Timson; 11-11-2006 at 04:41 AM.
    M3-CB, C3-HAIII, A2-RD, Fenix L1P, Fenix P1D-CE, Tri-Star Phaser, Inova T3, Mag85, SNII Clone, DD LuxIII Mag,

    , Hot-Diver

  2. #2
    Flashaholic* missionaryman's Avatar
    Join Date
    Oct 2005
    Sydney, Australia

    Default Re: Hotwire Dive Light (Underwater Kinetics)

    wow Tim excellent work - the smooth reflector in that large diameter will throw a pencil beam. Great job incorporating the hotdriver and nice to see an original mod
    "Let your light shine" - it's the one commandment we all obey...

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