With this light I wanted a powerful all-around light that I could carry on my belt with a mid-sized beam, similar beam as my 7xXPL convoy L2 mod. I had been planning to do this mod in a C8 but was considering ways to make it more powerful. So I started looking at the few 2 cell side-by-side format hosts available. The Spark SP2 is the most compact and best looking of this format, IMO. For a lot of pictures of how this light looks stock see here. Big thanks to djburkes for hooking me up with this particular host. :+1:
It has 4 dedomed XPL V6 1A emitters in 2s2p format powered by 2 18650 cells in series. The optics are narrow TIRs from LEDDNA. I estimate it pulls around 12A from fresh 30Q cells. It does right around 6000 lumens at 15s and 100Kcd at 30s, measured at 6m. The driver is a FET-only with TK’s e-switch ramping FW flashed. I piggy-backed a 5V regulator to get low standby drain.
This light comes stock with the cells in parallel. The design of the stock carrier also made me nervous with the positive and negative springs so close together, so I decided to just re-make the entire carrier and contact design. I made the carrier out of PVC sheet and rod that I had bought for a previous project. I think PVC is a versatile material to make things with; it is a thermoplastic so it can be worked and shaped easily when it’s heated past its softening point. It can also be strongly bonded to itself by solvent welding which is what I did here to bond the rods to the pieces of sheet.
The battery positive connects to the copper disk at the center and makes contact with the 17mm FET driver positive. The outer copper ring is battery negative and makes contact with the copper pieces glued to the driver board. This design separates the positive and negative more safely, and I can easily lock the light out by unscrewing by a fraction of a turn.
This light was actually a big motivator for my 7xC8 thrower. This light nearly has the output and throw of my 7xXPL L2 mod (about two thirds of) in a more compact package. I figured if I’m going to have a big light like the L2 I might as well make it really big, thus the idea for the 7xC8 light was born and I re-used the LEDs from the L2 build. I plan to put a modded H2-C driver in the L2 with XHP35 in single cell configuration.
But this quad is very over-powered. On full power the light heated up from around 30C to 60C in 1.5 minutes. I’ve got the ramping FW set up with a reference blink at 25% power which gives about 1 hour run time and is probably near thermally sustainable.
2s gives more output. Of course 1s2p would still be powerful, but I wanted to maximise performance. And I got the satisfaction of designing and making a new carrier and contact system.
This build brings up a question I’ve had and am facing now myself. When making copper contacts such like the ones in this build, is it best to leave it bare copper or coat it with solder or some other solution? Just wondering what will keep best electrical connection over time. I don’t want to pick up my light after a few months of no use and find it finicky and flickering. Anyone have some insight?
I made a couple small modifications and measured the current draw.
I measured the current draw by turning on the light on high for 1 min with fully charged cells then using my hobby charger to measure the charge put back into the cells. With 30Qs the current was 11.4A, and with Sanyo GAs the current was 10.6A. The output with the GAs was roughly 94% of the output with the 30Qs.
I added a plastic cylinder piece to better separate the positive and negative contacts on the cell carrier. I also added some PVC buttresses to the bottom of the carrier as the PVC is a bit thin and flexes some from the cell springs. This is only a problem with the carrier outside of the light; inside the light with the head properly tightened the stress is taken off of the cell carrier.
I also added a belt clip using a method I’ve used for several of my lights that didn’t come with one. It is a convoy clip-on belt clip with the “arms” broken off. Then the clip is lashed to the flashlight body with spectra/dyneema fishing line and strategically reinforced with epoxy. The attachment is very solid.
