I've taken these apart before. Contrary to popular belief, the ones I looked at did not contain a capacitor. In fact all the cheap supercapacitors I've seen have pretty high internal resistances which presents a problem, also really a supercapacitor isn't a great size. 3 LEDs @ 4.5V 20mA each would drain a 1F from 2.5V to 1v in 19 sec even with 100% efficient DC/DC conversion. I saw a rechargeable lithium ion coin cell in there. The specs showed it had only tens of mAH capacity too. The idea of "cranking for x seconds provides y minutes of light" only is correct in that the LED will be pretty dim for a lot of that time.
Anyhow I was wondering about how we could make the beefiest crank light with a top-of-the-line emitter in there and a larger lithium batt. The light I looked at had plenty of extra room inside! Of course the problem of "significant cranking required" is still there. And with a big lithium cell that could get wall-charged and run for hours and hours why you'd ever need to crank it for just a few minutes of extra light. But it'd be fun. Lithiums last a long time when stored mostly discharged, so actually yeah it could standby for years in a camper and get cranked up for like 10 min and run an emitter for a long time.
My question is this- does anyone know which cranks have the best current capabilities? IIRC the one I looked at was in the tens of mA when I shorted a current meter across the terminals and cranked it. So that's like a peak current capability! I'd be willing to use a crank which required more work to turn if it produced more output. That one didn't resist my cranking very hard anyways and I was expending more energy just moving my hands in that swirling motion than actually putting into the batt.
Oh and a better step-up converter too, we wanna get a decent amount of white light here of a single lithium cell. In half the cases I like the idea of just getting full power for as long as I can and letting it just shutoff instead of fading to like 1/4 intensity for 4x as long. A protected cell will already handle that shutoff, right?
Anyhow I was wondering about how we could make the beefiest crank light with a top-of-the-line emitter in there and a larger lithium batt. The light I looked at had plenty of extra room inside! Of course the problem of "significant cranking required" is still there. And with a big lithium cell that could get wall-charged and run for hours and hours why you'd ever need to crank it for just a few minutes of extra light. But it'd be fun. Lithiums last a long time when stored mostly discharged, so actually yeah it could standby for years in a camper and get cranked up for like 10 min and run an emitter for a long time.
My question is this- does anyone know which cranks have the best current capabilities? IIRC the one I looked at was in the tens of mA when I shorted a current meter across the terminals and cranked it. So that's like a peak current capability! I'd be willing to use a crank which required more work to turn if it produced more output. That one didn't resist my cranking very hard anyways and I was expending more energy just moving my hands in that swirling motion than actually putting into the batt.
Oh and a better step-up converter too, we wanna get a decent amount of white light here of a single lithium cell. In half the cases I like the idea of just getting full power for as long as I can and letting it just shutoff instead of fading to like 1/4 intensity for 4x as long. A protected cell will already handle that shutoff, right?
