Well I went and made another one. With this one I was shooting for efficiency and run time. So far so good. I started with a 2s2p 4x18650 protected battery box and I'm running 2300mAh Sanyo "used" unprotected batteries. So good cells but not expensive ones. ($2 each). This time I didn't use a driver at all and simply wired the box to 3T6 emitters with a switch in between. It's fairly bright, good enough to read by or play cards with and it light up most of a room half way decent. The emitters are mounted on a copper pipe inside a quart mason jar that was lightly dusted with white spray paint. A hole was drilled through the lid for the wires and the lid is sitting on the top of the box so it's very compact. I turned this on yesterday at noon and it's now just past 6am and it's still going and has not dimmed at all. There seems to be zero heat. The jar is cold as are the batteries. So it's been on for over 18 hours so far. Any guesses as to how long this will run? The protection on the battery pack cuts off at 2.40volts. Don't worry I won't let it get close to that low. Right now the batteries have lost less than .3volts. The two wires are for draining the capacitor on the protection in the box. The protection pops on each time the batteries are removed. Can someone tell me what to wire into those two so it will drain the capacitor without me having to do it with a battery? Would I just use a resistor and if so what kind would work? Oh and the emitters are only on one side of the copper pipe so I can turn it one way or the other to adjust the brightness and so the emitters are not stabbing you in the eye. I could have just sprayed the jar more but I think I got it about right. It's actually even nice to carry around outside. Just enough light to easily walk with and it keeps it bright enough to see all around for maybe 20 feet or so.
Funny how my mind didn’t even go there and I was deployed twice. I don’t think of the US as a war zone. I guess I should? but it’s just too far removed from the area I live in. Around here we are more worried about terrorist squirrels knocking out our power grid and ATF means just that. Alcohol, Tobacco and Firearms.
ATF parties are common around these parts. (skeet shooting parties, bring the family, pot luck lunch but the keg doesn’t get tapped until after the shooting when the kids have been taken home) Although I don’t drink or smoke tobacco I do stick around for the bonfire to play guitar with my buddies.
I work in a Federal building in downtown DC so I am always on the look out! If someone even writes me a hand written letter, it arrives all yellow and crinkly from being irradiated.
neat light, I especially like the careful use of black electrician’s tape, an essential part of any light build The 3 LEDs are in series, right? So they’ll each be at around 2.5v-ish, in which case they should be drawing a few hundred mA at most and that battery will last for 10s of hours. In fact, it’ll last longer the more the battery discharges as the decreased voltage will decrease the current drawn. If you want a rough guestimate, just check out Match’s (or Cree’s) mA vs. V curves to figure out current draw.
…but I suppose we could drop the ‘n’ and use them for white lighting as well… :bigsmile:
The 3 LEDs are in series, right? So they’ll each be at around 2.5v-ish, in which case they should be drawing a few hundred mA at most and that battery will last for 10s of hours. In fact, it’ll last longer the more the battery discharges as the decreased voltage will decrease the current drawn. If you want a rough guestimate, just check out Match’s (or Cree’s) mA vs. V curves to figure out current draw.