Free Lumens (Kind of)

I recently flashed a modern OS on to my soda-can quad light, the BLF Q8. The refreshed interface on the light brought my interests back to it and had me wondering… what else could I do with this light? After doing some reading around on various forums, I found out that the Q8’s output could receive a significant increase in output with a few fairly simple mods! One mod is what is call a “spring bypass”. The Q8 uses gold plated steel springs, and while they’re okay, they’re not the best springs you can use, as they create some resistance between the batteries and the light. A spring bypass is basically soldering in a better conductor between the top and bottom of the spring so that is exactly what I decided to do. I already had everything I needed for this one, a soldering iron, solder, and some wire.  I used 18 gauge copper wire and made the connections. It wasn’t difficult, but my soldering iron is really showing its age and I need to upgrade to a better one sometime soon.  Here’s what my tail PCB looked like after modding:

And don’t worry, I smoothed out that spiky looking solder at the top of the spring in the front after I took the picture 🙂

The next mod wasn’t as free, but it only cost me a few bucks, so it was well worth it. In addition to bypassing the springs, it is recommended you replace the screws that attach the tail PCB to the flashlight body. The factory screws are just steel (I think?). Replacing them with brass screws actually makes a better connection between the light and the PCB and can actually give you a +8% output boost all on their own. This one was simple since I already had the PCB out I just reinstalled with the brass screws I ordered online.

Here is the modded PCB installed with brass screws, featuring a bonus cat.

I built a lumen test box a while ago and calibrated my phone’s lux sensor based off a light with various known lumen output levels, so while I’m sure my rigged up box is not 100% accurate, I believe it to be within a few percent of accurate which is good enough for me. I had previously measured this light right at its factory output rating of 5,000 lumens. After finishing my mods, here was my new result:

Bam! Right where I should be with these mods! A 30% increase in lumens for some soldering and some new screws. Needless to say I’m very happy with the results, and my big lumen light just got even bigger.