Harbor Freight Free Flashlight Mod

thingiverse

UPDATE 1: The large face of LEDs has been on for quite some time now and they're getting remarkably hot. To mitigate this issue, I would strongly suggest increasing the value of the current limiting resistor from its current 1.5 ohm setting to a higher rating. UPDATE 2: A mathematical analysis reveals that using a 2.5 ohm resistor should effectively limit the current to each LED to approximately 50 mA. However, I must emphasize that this is merely an estimate and hasn't been put into practice yet. UPDATE 3: It appears that Harbor Freight has made some significant changes to their flashlight design. Instead of featuring twenty or so LEDs on the front, the newer model boasts three front-facing LEDs along with a single strip LED on top. Unfortunately, this modification renders my original design obsolete. UPDATE 4: Given that Harbor Freight now provides a free flashlight with their purchase offers, this particular mod is no longer relevant. I've kept it up in case anyone still owns an older version of the flashlight, and I highly recommend checking out [this alternative mod for the new style](https://www.thingiverse.com/thing:3776638). Harbor Freight occasionally sends me unsolicited promotional emails, often accompanied by coupons for purchasing items with a free, low-quality flashlight as a bonus. Recently, I decided to examine one of these flashlights more closely and was underwhelmed by its aesthetic appeal and functionality. Rather than leave it in its current state, I opted to improve its usability, even if not its looks. This redesign requires an 18650 cell and a 5v battery charger circuit, as shown in the accompanying diagram. Given my abundance of these boards and cells, I put this project together fairly quickly. It makes use of six screws from the original design to hold it together and reuses the magnet at the bottom (if you can even call it that). The assembly process should be clear from the photos and board labels. Please ensure that the screws don't become misaligned in their respective holes, as I've encountered this issue a couple of times. However, it's an easy problem to rectify. Additionally, please note that the value of the current limiting resistor should be set at 1.5 ohms, so replace it with a 1.5 ohm resistor if necessary or lower than 1.5 ohms. To prevent any potential shorts, place a small piece of tape over the positive terminal of the battery. The model I printed was made from PETG, so don't expect your PLA print to withstand the same level of stress. Consider using stronger materials for better results. In an attempt to showcase the difference in brightness between the stock and modded versions, I took several photos, but this proved to be a difficult task. The modified version is indeed brighter and should last longer than the stock batteries. To avoid damaging the battery, do not solder directly to its terminals. The battery charging boards I purchased have a unique feature - they don't allow any current flow from the battery until they're plugged into a 5v micro-USB power source first. Keep this in mind when you're wondering why your setup isn't functioning as expected. When attaching the wire legs on the back, keep them very short and remove just enough material from the overhanging bit that keeps the board in place. Remove only what's necessary to allow the board to rest comfortably in its designated spot, then apply a small amount of CA glue to secure it firmly in position.