Harbor Freight Free Flashlight Mod by Phistterbut_Inc

Last crawled date: 3 years ago

UPDATE 1: I've had the large face of LEDs on for a while and they get PRETTY DAMN HOT. I would increase the value of the current limiting resistor from the 1.5 ohm to a greater value.
UPDATE 2: Math shows that 2.5 ohms should be a good value for the resistor and should limit the current to each to around 50 mA. I said, SHOULD. Don't quote me on that, haven't replaced mine yet.
UPDATE 3: Seems that HF has changed up the flashlight a bit. In lieu of twenty some odd LEDs, the newest style has three front facing and one strip LED on top. This thing won't work for the updated version, sad day. They did however change the board a bit.
Update 4: Since they've changed the flashlight they give out for free, this thing is obsolete. I won't delete it in case anyone still has one but I recommend this mod for the new style
Now and then Harbor Freight sends me spam mail, tons and tons of spam. They send these coupons for a buy an item get a crap flashlight for free. Well, I got to looking at the thing and decided it's ugly and nearly useless as is. Rather than be both, I improved the use, but not the looks.
This design calls for an 18650 cell and a 5v battery charger circuit as pictured. I've got a ton of these boards and quite a few cells, so I tossed this together. It uses six screws from the original to hold it together and reuses the magnet (if you can call it that) at the bottom. Should be clear from the photos and board labels how to put it together.
Make sure the screws don't get cockeyed in their respective holes. Had that happen a couple times, but it's an easy fix.
Also, the value of the current limiting resistor should be 1.5 ohms, replace with an 1.5 ohm resistor if it's out of spec, or lower than 1.5 ohms.
Place a bit of tape over the positive terminal of the battery as to prevent shorts.
What's pictured was printed in PETG so don't complain when your PLA print breaks, just use stronger materials.
I tried to capture the difference in brightness between the stock one using 3 AAA batteries and the modded version, but that was quite a fools errand. This version is brighter and should last longer than the stock batteries.
Don't solder directly to the terminals of the battery, that will likely damage it.
These battery charging boards I bought don't allow any current to flow from the battery until they're plugged into a 5v micro-USB power source first. Something to keep in mind when you're wondering why it doesn't work. Keep the wire legs very short on the back and remove just enough material from the overhanging bit that keeps the board in place. Remove just enough to where the board will rest in place, then apply a small amount of CA glue to keep it there.