Glad to hear I’m not complete barking up the wrong tree here, will be giving this a go as soon as the parts arrive.
What’s the general consensus on here about flashlights that use external power packs for big lumen output, is it considered cheating?
On the 7135s that’s a very clear way of explaining how they work and confirms what I’ve been seeing in terms of heat dissipation and efficiency. Will be interesting to see how they handle what i’ve got planned. I suspect I’ll have to stack them vertically inside a heatsink tube or brass pill that can suck the heat off directly. Actually I’m excited I can do something else with these drivers, still have 40 of the little 0.380A fellas in a drawer and they need a home.
Today I was playing around with making a flexi-cord from various power cords I had lying around. Trying out various thicknesses and materials. Ultimately I want to have a spiral wound flexi-cord to connect the flashlight to the lipo pack and at 15Amps it needs to be pretty substantial to not suck up all my precious volts before they even get to the regulators!
Made them all “spirally” by winding tightly around a dowel and heating them as much as I dared with a heat gun then let cool. Works ok and they stay wound, but the materials found here are not quite as keen to return to their fully wound state as I’d like.
I found that even for a relatively short reach of around 45cm (in it’s semi wound state, quite a lot longer unwound) the resistance losses really add up quickly. My best result of the day was with a shaver power cord that has what looks like 18awg copper core wires inside. Best result, as in it didn’t weigh half a tonne because of excess plastic coating (white cable) or heat really quickly and drop almost 1.7v under the test load (thinner black cable). That said it still dropped just over 0.8v on my test rig at 15A which I hope will come down once everything is soldered tight and the excess cable trimmed. It’s certainly something I’ll need to keep an eye on as it will have a fairly big effect on the whole power setup and I don’t think I can go much thicker on the cord without making it too heavy and cumbersome. Obviously there’s no point in having a stout battery pack that doesn’t sag when you lose all the benefits getting that power to where it’s needed!
The winner
The test arena
The rejects
Should probably start a new thread for the BTU planning and tinkering…
Cheers