I got loads of old sub-c batts lying around, so I’m thinking of wiring up three cells in series, to DD an XML, which will be glued to an old athlon XP heatsink, with AA thermak adhesive. the idea is to make a beefier ‘solar light’ than those run of the mill 5mm led /nimh AA jobs you buy at walmart.
got plenty of old 4.5v solar cells, and a fair number of photocells lying around, so parts are easy. the led wont be powered during charging, so no need for a resistor on the solar panel, but I’m not 100% certain if 3 1.3ah sub c cells (3.6v) would run an xml very long. Its obviously not going to put out enough juice to warrant the extra cost of a driver (I have a few XML’s lying around already, so we’re literally talking zero-cost here except for solder/flux, and electricity to run the iron.
the heatsink is from an old athlonxp, 2100+ computer cpu.
wondering what everyone’s opinions would be on such a build. (I’ll post pics when its done).
You could parallel a few sets of cells if the charge current is kept low. (1/10C) 7135’s don’t require extra parts so you could use them to limit current and extend runtime.
Are your sub-c’s ni-cad’s. Ni-cd’s can dump a whole lot of current. Direct drive would probably fry the emitters. You may want to get some 7135 chips. They are cheap from Fasttech and ebay. Each chip will supply 350 mA. Wire in parallel to increase current to level you want. Here’s a thread on wiring 7135’s:
ok thanks for the info, and yes they’re ni-cd. going to use two 7135’s with each light to drive the xml’s at 1050ma. nice even light while still maintaining runtime., and 5 banks of 3 cells each, for a total of 6500mah.I know that’s pitifully driven, but for what I need it works. It should last several hours, and turn off at daylight thanks to the photocell I’m including. the solar panels will recharge the batts, and it should work well. With this heatsink I could drive the emitters at full 3000ma, but that would defeat the purpose of this build as runtime would be short.
still at 1050ma, a single XMl T6 puts out way more light than those standard 5mm leds used in most solar lights. these suckers should adaquately light up my yard for late night barbecue cookouts, without costing a dime on the electric bill, as they’re solar-charged. If it works out well, I may revisit the build later, and add a ramping driver that starts at 350ma, and winds up to around 1.5A as it gets darker out, then steps down again as it starts to get daylight, but for now, I’ll be using the photocell solely to switch the lights on and off, and they’l be driven at a constant current of 1050ma.
I got some laptop 18650’s I could use too, but right now I’ve got a mountain of old sub-c powertool batteries to recycle/repurpose, so I’ll be using those first.
I considered using XP-e for the lower power drain, but I already have several t6 XMl emitters left over from upgrades so I’ll make do with those.