Really, Really! long lasting flashlight for cheap.

Cheap/easy to build *BRIGHT!* flashlight that can bring light to the dark parts of the world and in emergency situations.

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A twist on crystal cells to actually make them usable and to take old batteries and make them last a really long time.

I built this project to see if crystal cells could actually be used in a real world application. I have built/seen other peoples prototypes of crystal cells and found them to be something of a novelty and lacking; they didn't really power useful devices except multi-year motors that had no load, and multi-year led night lights that couldn't light up a room or be useful as a flashlight. I also seen people use the same electrolyte in lead batteries to extend them and make them indestructible at low voltages (can be shorted for days on end and they bounce back). I thought why not combine them both and make something that you can actually use and walk around with...albeit carefully. Its been 5 days so far, and the light hasn't extinguished. The light is as bright as 3 days ago when the voltage dropped to about 3.4-3.5v and hovered in between. The amperage has been steady at .5 amps. Time will tell if this battery lasts a long time but so far the curve has disappeared.

  • 1 × EverStart ES12N94B1 Motorcycle Battery The kind you normally have to fill with acid;get one that has a top thats slightly smaller than the lanterns side thickness(so it will fit on top)
  • 1 × Rayovac 10 LED 6V Floating Lantern 85 Lumens
  • 1 × Epsom salt- 100% Magnesium sulfate. non-scented. Maximum possible concentration diluted in distilled water.
  • 2 × 12 AWG wire Red and Black at least 1 foot (30cm) each.
  • 1 × Yellow Termanal crimp connector Makes connecting the wires to the battery easier

View all 9 components

  • New development

    David Thomas04/22/2015 at 03:27 0 comments

    After I shut it off for 24 hours, it did what I thought, it traded volts for amps and shot up to 2.7 volts and .012 amps. It will barely show as bright as a candle. Unfortunately I don't have time to mess with it as I have to go on a business trip(no fun). But when I get back I will recheck it to see if there was a "crystal cell self recharge affect". If that doesn't work I will try to revive the battery by recharging it.

  • Tonight I turn it off to see if it "recovers"

    David Thomas04/18/2015 at 04:50 0 comments

    Already it has lasted 9 days constantly on.... Not many (actually any) flashlights I know of last that long, with so much brightness. So even now the project is a success.

    Today I read 2.7v and .17 amps. The flashlight is still bright enough to light up a room pretty well and very usable as a flashlight. Brightness is now on par or better than my old incandescent 6v flashlight with fresh batteries. The onboard volt meter no longer registers(needs 3v). So tonight I will turn it off to see if it "recovers" like most say. My prediction will be that the voltage recovers, but the amps will still be weak.

    Again no charging!

  • Whats up in the far future.

    David Thomas04/15/2015 at 06:54 0 comments

    If this is a successful test(over a week and with no permanent damage to the battery). I hope to scale up to larger motorcycle batteries (possibly 3 of them for a total of 12v) and connect them to a thyroid transformer, or inverter to power larger loads. Or I may go another route and forgo the lead all together. The main reasons why I used lead batteries:

    1.) Availability

    2.)Recycle-ability(lots get thrown away everyday)

    3.)Mature tech(less guessing and prototyping)

    4.)Plate distance & "surface area:mass ratio" (greater power output and energy density than youtube style pipe crystal cells).

  • .3 amps and dwindling!

    David Thomas04/15/2015 at 03:32 0 comments

    still 3.4 volts .3 amps now. No changed noticed in brightness. This is getting exciting!

  • You can use old junk batteries!

    David Thomas04/14/2015 at 19:40 0 comments

    You can use old motorcycle batteries for this project. About 75% of the time people throw away good lead acid batteries that are just behind on their maintenance! In fact after restoring them you may get more output due to the charge plates being already fully formed due to acid exposure during charging. You may want to check out youtube on how people restore them (and dump the acid) and use the method you think is best. Good search criteria is: alum battery conversion, or lead battery restore. After restoring the battery with the acid in it, just remove the acid, and substitute the final electrolyte with the epsom salt/distilled water mixture.

    But remember when dealing with the old, now useless can burn you.... and lead is poisonous.

    Notice alot of these videos teach you how to dispose of byproducts properly and handle it; such as wash your hands, or any surface your hands might touch with soap and water when your finished dealing with lead(found on the terminals and in the acid). Also wear gloves, old long sleeve shirts, pants, and eyewear when dealing with acid. Wash any part of your body that comes into contact with it immediately or it will burn over time. Dispose of it properly in a clean sealable plastic painters bucket ( call local hazmats at your garbage dump and/or battery recycling place, usually a free service). Not all encompassing but it covers most of the hazards.

  • Below .5 amps

    David Thomas04/14/2015 at 18:47 0 comments

    At the .48 amp mark. Still 3.4 volts. No visable difference in light output.

  • To be clear, I am not going to charge it

    David Thomas04/14/2015 at 15:25 1 comment

    I expect that the cell will eventually go down below 3 volts or output very little light at some point. Weather if thats a week, month, year or years, I won't know. But If that's so, I will let the crystal cell recover for 24 hours then see if I get the same shorting amps and voltage as before. I am going to let this baby ride

    Still at 3.43 Volts .5 amps today.

  • 5 days and still Bright

    David Thomas04/14/2015 at 09:20 0 comments

    I initially bought a motorcycle battery, filled it with distilled water and epsom salt (magnesium sulfate). The epsom salt is dissolve in as much as the water will allow. Blender helps...adding little by little, and blending till its clear again, then add more till the water can no longer hold any more (there is some at the bottom no matter how much you blend it).

    I charged it up to 12 volts on my car battery charger, in parallel with another 12volt battery. I then ran it down to 10 volts by connecting it a 12v inverter with a light bulb load, and draining it. I then ran it down to 6 volts by shorting it on and off... but long story short(hah), I got it down to the 6 volt sweet spot, that crystal cells need to run.

    I then cut the housing ("battery side") for the lantern and test fit it on top. I soldered the wire on the contacts where the "Normal" 6v lantern battery connects to; If you look at the "bulb side" of the housing The outside C ring is positive, the inside circle is negative. I then crimped on some automotive yellow "crimp terminals".

    Its been on the whole time except 1 or 2, 5 min tests. The first day it went from 6 volts to 4.5, second it went to 3.64, 3rd it hovered between 3.4 and 3.5v. 4th same 3.4-3.5v. 5th 3.4-3.5v. Also for the last 3 days the battery short amperage is .5 amps. For the past 3 days the brightness has not changed and is the brightness that is in the pictures. I will try to log the progression past this point.

View all 8 project logs

Enjoy this project?



zakqwy wrote 04/14/2015 at 14:16 point

Have you thought about datalogging current and voltage through the discharge cycle so you can quantify watt-hours? That seems like the most relevant measurement for battery performance IMHO.

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David Thomas wrote 04/14/2015 at 15:19 point

I have thought about it there are 2 problems with that. 1.) I don't have datalogging abilities, so I will just update here, as I have free time. 2.) I think adding any type of  constant metering device permanently, will change the circuit, thus impacting performance.

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zakqwy wrote 04/14/2015 at 15:33 point

Are you intending to quantify the performance differences between this battery chemistry and other options, such as lead-acid, NiMH, NiCad, LiFePO4, etc? Energy density, discharge curve, that sort of thing? 

I doubt current monitoring will change the circuit much if you do it carefully. Use a high-amperage shunt with a millivolt-level voltage drop; you can pretty easily calculate its effect on the data.

Can you provide any more info on epsom salt batteries? I'm not familiar with them.

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David Thomas wrote 04/14/2015 at 15:51 point

Crystal cells have a anomaly that they are really hard to get them to fail or show 0v. They are also pretty hardy in that you can take lead batteries really to low voltages. I intend to test that limit in a practical application. Lead/Epsom salt battery was chosen because epsom salt doesn't expand as much as alum and I was worried about plate damage. I am not stacking it up against other traditional battery, tech because it will lose with power density. I'm just seeing if its viable to use, and as long lasting as some claim.

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zakqwy wrote 04/14/2015 at 15:52 point

Makes sense! Good luck, thanks for the responses!

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Xeon wrote 04/14/2015 at 12:35 point

Made something like this not too long ago.

It lasted me 1 month, 12 days, 3 hours.

But I opted to use a high speed pulse to fill a capacitor and then fed the power to it from there.

Good luck :)

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David Thomas wrote 04/14/2015 at 15:19 point

Please give me a link to your work, and thank you! :) I hope it lasts for at least a month.

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Xeon wrote 04/14/2015 at 17:26 point

I never documented it, so go ahead. 

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