Own The Night With This Ludicrously Bright DIY Flashlight

big LED flashlight

If you’re a flashlight person, you know that there’s little you would do to get the brightest, most powerful, most ridiculous flashlight possible. You might even decide to build yourself a ludicrously powerful flashlight, like [Maciej Nowak] did.

If you choose the DIY route, be warned that it’s probably not going to be a simple process, at least if you follow [Maciej]’s lead. His flashlight is machined out of aluminum rounds, all turned down on the lathe to form the head of the flashlight. The head is made from three parts, each of which acts as a heat sink for the five 20-Watt CREE XHP70 LED modules. The LEDs are mounted with care to thermal considerations, and wired in series to DC-DC converter that provides the necessary 30 V using a battery pack made from four 21700 Li-ion cells. The electronics, which also includes a BMS for charging the battery and a MOSFET switching module, form a tidy package that fits into the aluminum handle.

The video below shows that the flashlight is remarkably bright, with a nice, even field with no hotspots. Given the 45-minute useful life and the three-hour recharge time, it might have been nice to make it so anywhere from one to five of the LEDs could be turned on at once. Some interesting effects might be had from switching the LEDs on sequentially, too.

Given the proclivities of our community, it’s no surprise that this is hardly the first powerful flashlight we’ve seen. This one broke the 100-Watt barrier with a single COB LED, while this ammo-can version sports an even higher light output. Neither of them looks much like a traditional flashlight, though, which is where [Maciej]’s build has the edge.

27 thoughts on “Own The Night With This Ludicrously Bright DIY Flashlight

    1. Look in your area for a scrap metal dealer or metal recycler. Sometimes they’ll let you buy scrap. Machine shops dump tons of aluminum cutoff but they’re sufficiently valuable they end up at the recycler’s.
      I’ve a local aluminum recycler/reseller that has a bin a meter across, a meter deep, by about 5 meters long, full of lathe cutoffs from 20mm up to 15cm in diameter, that he sells for about $2/kg.

    1. why exactly? at least in my area there is no laws on lighting. the people who go out gigging at night can literally use as many lights with generators as they like. It is pretty annoying sometimes but perfectly legal.

          1. When my little sister was in High School, her English teacher told the class that an egg is the only food you can poach.
            She corrected him, saying deer can be poached as well.

    1. Well, maybe he meant to say that. There is little *I* would do to “get the […]most ]ridiculous flashlight possible”… because such a thing is impractical to the point of uselessness, except for youtube clicks. OK, youtube clicks and deer jacking.

  1. Genuine question from a battery noob : how charging take more time than running time? I thought this trend (charging time > usage time) was over since the 90’s (I remember my nickel-cadmium RC car taking 5 hours to charge for about 20minutes of playing time) thanks to new battery chemistries. What am I missing there?

    1. Battery chargers do have their limits, which vary a lot depending on how they are made.

      Maciej’s charger is probably underpowered, with less than 25W of output. A 50W charger could do the job in about an hour. At the risk of reduced battery life, a charger capable of 100W would easily charge the battery pack in about 30-45 minutes.

      Since the flashlight appears to use an external charger, Maciej could easily upgrade to a faster charger in the future with no modifications.

  2. No, pretty normal for applications where you push Li-Ion cells hard. They’d prefer a slower discharge of course, but they’ll survive high discharge currents you can’t safely charge them with.

  3. I was somewhat skeptical because 45 min sounded pretty long for a circuit that consumes over 100W (considering the other modules and the dc converter’s efficiency)

    A quick math would be something like 45*60s*100W = 270kJ of energy spent (at least)

    If we assume that each Li-ion cell has 3.7V and 5000 mAh of capacity, it would give us 4*3.7*5 = 74 Wh or 266.4 kJ

    Which is reasonably close, and it makes me seem like a fool :)

    1. Nah, just means you haven’t played around with LiIon batteries enough.

      21700 cells are bigger than the 18650s, and have about 30-50% more capacity, so the 5000 mAh rating is probably not even all that wrong. (You can find 18650s that claim 4500 mAh, or whatever, but they’re bald-faced-lying.)

      Heck, if you put enough of them together, you can drive a car. For more than 45 minutes. :)

      But yeah, it’s surprising how much energy is in LiIon/Po/FePo cells.

  4. The video states that the LEDs are connected in parallel, but the visual seems to show that they are connected in series. The specs of the cree xhp70 LEDs states these work with 6V. So they are connected in series.

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