This is really two stories married together.
- Last winter I embarked on a quest to replace my entire lighting system using the DC-DC Converter P/N #VKP60MT312. Related thread here and here.
- The single-most issue with using the converter was finding a heat sink.
- Sourcing the Cree Ultrafire HP-LED was fraught with angst as the original supplier DealExtreme kept stalling on delivery. Fed up I cancelled the order after waiting 3 months. Related thread here.
- After many weeks I secured a like-replacement Cree UniqueFire from DinoDirect which arrived promptly and without issue.
- Mounting hardware for the flashlights was ordered off of eBay; I chose two models though the winner of the evaluation was obvious upon arrival. Related thread here.
- Small items used for assembly were 125V/10A SPST Rocker switches purchased from Radio Shack, and pieces cut from a square-foot x 1/16th-inch thick sheet of neoprene rubber which I had on hand.
I bought Qty-3 of the UniqueFire X8 Cree XP-G R5 300L HP-LED Flashlights from DinoDirect for just over $100. It comes fully assembled sans battery and charger. Workmanship on the flashlight was very good and without obvious flaws.
In the image below Ã¢â‚¬â€œ the reflector in the upper-right was the only item that DealExtreme shipped to me: It wouldnÃ¢â‚¬â„¢t fit the UniqueFire light nor could be adapted. You can wager DealExtreme will not be receiving a Hexmas card from me.
To convert the flashlight from AAA battery to electric, I took a length of square balsa rod which was purchased from a hobby store, removed the end-cap of the flashlight, inserted the wood all the way into the battery tube, marked the end, and then cut off the rest. The image below shows a completed modification at the top, and one in progress below.
Note: Balsa is a light and very soft wood whereas Pine, Acrylic, or Nylon rod would make for stronger alternatives. Time will tell if the balsa holds up.
I used a 7/32-inch drill bit to make the hole into the side of the battery holder as indicated below. Using 18-AWG speaker wire, I crafted the pseudo-battery using the cut balsa as the placibo & where each end of the wire has a nice large blob of solder for a contact, depressing it into the soft ends. The wire is secured by a few wraps of electrical tape. Note that the Negative end is wrapped to a diameter that nearly equals the battery, and in fact is a snug fit within the holder. Some experimentation is required to produce the right fitting.
Contrary to natural thinking I reversed the mounting hardware so that it Ã¢â‚¬Å“pointedÃ¢â‚¬Â backward on the handlebar. With the image below, Ã¢â‚¬Å“frontÃ¢â‚¬Â would be on the left. Reason being is that when the head-piece of the light is attached, the whole assembly is nearly balanced over the handlebar Ã¢â‚¬â€œ which is very important considering the weakness of the attachments. I cut out a piece of neoprene to wrap around the entire battery tube; this did a much better job of creating an even fit across the length of the fixture. When this is assembled, rotate the unit so the the wires drape out the bottom directly and insert into the fixture with the clamping fastener for the light removed. This will allows the wires to slip into the slot snugly just right of the handlebar fastener. The head-piece is screwed on last.
Small notes: All the fastening hardware that came with these mounts are shite; best to replace it all with Allen-head screws to prevent tampering or dropping out due to vibration. Also the rubber provided was not large enough to enable a secure clamp therefore I built up the size around the tube by cutting two strips of neoprene rubber ~ Â¾-in x 4 inch that I wrapped tightly around the handlebar and secured with electrical tape where the flashlights would eventually go.
Mods to the DC-Converter:
I bought the heat sink off of eBay for $1.00 each Ã¢â‚¬â€œ thatÃ¢â‚¬â„¢s right! It cost more to ship it to me. The heat sink is really low profile Ã¢â‚¬â€œ lower than I anticipated. But itÃ¢â‚¬â„¢s better than a poke in the eye. It even came with mounting screws! However - without nutsÃ¢â‚¬Â¦ itÃ¢â‚¬â„¢s kinda futile but whatever; they went into the parts bin. The holes did not match up closely with the DC-Converter and had to modify them with a drill which was cumbersome Ã¢â‚¬Â¦ meh; part of the job. Fasteners that work: 4-40 x Â¾-inch or M3-20mm will do in conjunction with aircraft nuts and no washers. My local Ace Hardware has a better selection than the Home Despot.
The backside of the heat sink had this graphite-like slippery yet delicate material. I did not use any compound between the surfaces during the joining.
I decided to keep the default voltage at 3.3V without trimming or other adjustment, however I did add a small 470ÂµF 35V electrolytic capacitor on the output side to assuage the ripple and buffer the load. In the image below the Secondary ON/OFF shorted to Ground for constant operation. Again 18-AWG Radio Shack speaker wire was used. The rest of the unused pins were covered by a short snippet of heat shrink tubing, and then plastered all down with electrical tape.
I took three photos Ã¢â‚¬â€œ none represent what I actually saw however the image below is likely the closest. The wall is 6-feet away. The lights are very bright and I did my best to avoid looking directly at the reflections. I was hoping for better spread; instead there is a strong center annulus enveloped by a profoundly weak flood. It is what it is Ã¢â‚¬â€œ though I expected better. Methinks this is all a function of the reflector, thus the hunt continues. However Ã¢â‚¬â€œ it is a much brighter and whiter light than the two 10W halogens they replaced.
I had secured the heat sink to the Converter with zinc-plated screws. Afterwards the modified regions of the heat sink where I filed and drilled were given a quick dash of hi-temp engine paint, then cured it on top of an oil space heater. While sorting out the wiring and doodads I left the whole assembly turned on for 3 full hours. On a 40-Ah battery it registered about a 0.1 Ah drop/hour. The little heat sink was toasty enough to keep biscuits quite warm, and perhaps would make for a perfect bum-warmer if one could figure out an arrangement below the seat. However it never did get too hot to touch in a static room-temp environment Ã¢â‚¬â€œ though I wouldnÃ¢â‚¬â„¢t want it to get any warmer. Come summer I should source a larger heat sink. On the flip-side and to my complete surprise the Cree flashlights barely registered any warming.
The image below displays the DC-Converter mounted on the neck of the handlebar for best exposure.
Top-down view of the assembly almost directly over handlebar post. (Apologies for the glare of the CA). The heat sink is the squarish shape on the left of the post. Two toggle switches are on the right above the obscured controller. I kept the old battery-powered headlamp in the center as a backup. The flashlights can be turned-on or have their mode set individually though I prefer to have a master headlight switch (upper/closest to the CA). The lower one is the Power Switch to the DC-Converter, and is useful for arresting the 0.5W patristic drain even when there is no load.
Flashy Taillight mod:
I use a pair of Planet Bike Super-Flash blinkies for tail lights when riding day or night. The 3.3V out from the Converter goes to a pair of 18-AWG Trailer Connectors: One serves the Cree flashlights, and the other connects to the Super-Flash blinkies in the rear. Modifying the blinkies was pretty straight-forward: Remove the AAA batteries, bend out the contacts, and solder the pre-tinned wire ends. I then notched the sides of the casing. As an afterthought I applied Urethane sealant to the wire and slots to repel moisture. Two views below show the completed assembly.
The blinkies are connected directly to the output of the Converter which is controlled by the Power Switch. When turned on, they are at least as bright and strong as a brand new fresh pack of batteries Ã¢â‚¬â€œ and probably more so being very highly visible; an unexpected though most-welcomed benefit!
All the little details took time; I spent maybe one short day including running about getting the missing pieces together. BTW - the 18-AWG wire never gets warm, though I will probably use the heat sink to warm my hands come winter. Now that I have a LiPo-enabled Auxiliary electrical circuit maybe itÃ¢â‚¬â„¢s time to consider other niceties such as running lights or turn signals. Then again there is that unused plasma cannon sitting in the corner collecting dust: Might be time to clear the roads of obnoxious verminÃ¢â‚¬Â¦